release v0.5.3

* smurf ethics

* smurf ethics

* removed auto ddp fix

* removed auto ddp fix

* removed auto ddp fix

* removed auto ddp fix

* removed auto ddp fix

* removed auto ddp fix

.codecov.yml

@@ -0,0 +1,46 @@
+# see https://docs.codecov.io/docs/codecov-yaml
+# Validation check:
+# $ curl --data-binary @.codecov.yml https://codecov.io/validate
+
+codecov:
+  notify:
+    require_ci_to_pass: yes
+
+coverage:
+  precision: 0  # 2 = xx.xx%, 0 = xx%
+  round: nearest # how coverage is rounded: down/up/nearest
+  range: 40...100 # custom range of coverage colors from red -> yellow -> green
+  status:
+    # https://codecov.readme.io/v1.0/docs/commit-status
+    project:
+      default:
+        against: auto
+        target: 99% # specify the target coverage for each commit status
+        threshold: 20% # allow this little decrease on project
+        # https://github.com/codecov/support/wiki/Filtering-Branches
+        # branches: master
+        if_ci_failed: error
+    # https://github.com/codecov/support/wiki/Patch-Status
+    patch:
+      default:
+        against: auto
+        target: 40% # specify the target "X%" coverage to hit
+        # threshold: 50% # allow this much decrease on patch
+    changes: false
+
+parsers:
+  gcov:
+    branch_detection:
+      conditional: true
+      loop: true
+      macro: false
+      method: false
+  javascript:
+    enable_partials: false
+
+comment:
+  layout: header, diff
+  require_changes: false
+  behavior: default  # update if exists else create new
+  # branches: *
+

.github/BECOMING_A_CORE_CONTRIBUTOR.md

@@ -0,0 +1,59 @@
+# How to become a core contributor
+
+Thanks for your interest in joining the Lightning team! We’re a rapidly growing project which is poised to become the go-to framework for DL researchers! 
+We're currently recruiting for a team of 5 core maintainers. 
+
+As a core maintainer you will have a strong say in the direction of the project. Big changes will require a majority of maintainers to agree.
+
+### Code of conduct  
+First and foremost, you'll be evaluated against [these core values](https://github.com/williamFalcon/pytorch-lightning/blob/master/.github/CONTRIBUTING.md). Any code we commit or feature we add needs to align with those core values.
+
+### The bar for joining the team   
+Lightning is being used to solve really hard problems at the top AI labs in the world. As such, the bar for adding team members is extremely high. Candidates must have solid engineering skills, have a good eye for user experience, and must be a power user of Lightning and PyTorch.
+
+With that said, the Lightning team will be diverse and a reflection of an inclusive AI community. You don't have to be an engineer to conntribute! Scientists with great usability intuition and PyTorch ninja skills are welcomed!
+
+### Responsibilities:
+The responsibilities mainly revolve around 3 things.
+
+#### Github issues
+- Here we want to help users have an amazing experience. These range from questions from new people getting into DL to questions from researchers about doing something esoteric with Lightning
+Often, these issues require some sort of bug fix, document clarification or new functionality to be scoped out.
+
+- To become a core member you must resolve at least 10 Github issues which align with the API design goals for Lightning. By the end of these 10 issues I should feel comfortable in the way you answer user questions
+Pleasant/helpful tone.
+
+- Can abstract from that issue or bug into functionality that might solve other related issues or makes the platform more flexible.
+
+- Don’t make users feel like they don’t know what they’re doing. We’re here to help and to make everyone’s experience delightful.
+
+#### Pull requests
+
+- Here we need to ensure the code that enters Lightning is high quality. For each PR we need to:
+- Make sure code coverage does not decrease
+- Documents are updated
+- Code is elegant and simple
+- Code is NOT overly engineered or hard to read
+- Ask yourself, could a non-engineer understand what’s happening here?
+- Make sure new tests are written
+- Is this NECESSARY for Lightning? There are some PRs which are just purely about adding engineering complexity which have no place in Lightning. 
+Guidance
+- Some other PRs are for people who are wanting to get involved and add something unnecessary. We do want their help though! So don’t approve the PR, but direct them to a Github issue that they might be interested in helping with instead!
+- To be considered for core contributor, please review 10 PRs and help the authors land it on master. Once you've finished the review, ping me 
+for a sanity check. At the end of 10 PRs if your PR reviews are inline with expectations described above, then you can merge PRs on your own going forward,
+otherwise we'll do a few more until we're both comfortable :)
+
+#### Project directions
+There are some big decisions which the project must make. For these I expect core contributors to have something meaningful to add if it’s their area of expertise.
+
+#### Diversity
+Lightning should reflect the broader community it serves. As such we should have scientists/researchers from 
+different fields contributing!   
+
+The first 5 core contributors will fit this profile. Thus if you overlap strongly with experiences and expertise as someone else on the team, you might have to wait until the next set of contributors are added.
+
+#### Summary: Requirements to apply
+- Solve 10 Github issues. The goal is to be inline with expectations for solving issues by the last one so you can do them on your own. If not, I might ask you to solve a few more specific ones.
+- Do 10 PR reviews. The goal is to be inline with expectations for solving issues by the last one so you can do them on your own. If not, I might ask you to solve a few more specific ones.
+
+If you want to be considered, ping me on gitter and start [tracking your progress here](https://docs.google.com/spreadsheets/d/15D58gp8DvI0Z6qbbYVRuaWioiwzafcP58-UlbuO_CMU/edit?usp=sharing).

.github/CODE_OF_CONDUCT.md

@@ -0,0 +1,76 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, sex characteristics, gender identity and expression,
+level of experience, education, socio-economic status, nationality, personal
+appearance, race, religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+ advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+ address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+ professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account, or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at waf2107@columbia.edu. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see
+https://www.contributor-covenant.org/faq

.github/CONTRIBUTING.md

@@ -0,0 +1,53 @@
+# Contributing    
+Welcome to the PyTorch Lightning community! We're building the most advanced research platform on the planet to implement the latest, best practices that the amazing PyTorch team rolls out!   
+
+## Main Core Value: One less thing to remember    
+Simplify the API as much as possible from the user perspective. Any additions or improvements should minimize things the user needs to remember.   
+
+For example: One benefit of the validation_step is that the user doesn't have to remember to set the model to .eval(). This avoids all sorts of subtle errors the user could make.  
+
+## Lightning Design Principles   
+We encourage all sorts of contributions you're interested in adding! When coding for lightning, please follow these principles.    
+#### No PyTorch Interference   
+We don't want to add any abstractions on top of pure PyTorch. This gives researchers all the control they need without having to learn yet another framework.    
+
+#### Simple Internal Code    
+It's useful for users to look at the code and understand very quickly what's happening. Many users won't be engineers. Thus we need to value clear, simple code over condensed ninja moves. While that's super cool, this isn't the project for that :)      
+
+#### Force User Decisions To Best Practices    
+There are 1,000 ways to do something. However, something eventually becomes standard practice that everyone does. Thus we pick one way of doing it and force everyone to do it this way. A good example is accumulated gradients. There are many ways to implement, we just pick one and force users to use that one. A bad forced decision would be to make users use a specific library to do something.    
+
+When something becomes a best practice, we add it to the framework. This likely looks like code in utils or in the model file that everyone keeps adding over and over again across projects. When this happens, bring that code inside the trainer and add a flag for it.
+
+#### Simple External API    
+What makes sense to you may not make sense to others. Create an issue with an API change suggestion and validate that it makes sense for others. Treat code changes how you treat a startup: validate that it's a needed feature, then add if it makes sense for many people. 
+
+#### Backward-compatible API   
+We all hate updating our deep learning packages because we don't want to refactor a bunch of stuff. In Lightning, we make sure every change we make which could break an API is backwards compatible with good deprecation warnings.
+
+You shouldn't be afraid to upgrade Lightning :)
+
+#### Gain User Trust    
+As a researcher you can't have any part of your code going wrong. So, make thorough tests that ensure an implementation of a new trick or subbtle change is correct.    
+
+#### Interoperability  
+Have a favorite feature from other libraries like fast.ai or transformers? Those should just work with lightning as well. Grab your favorite model or learning rate scheduler from your favorite library and run it in Lightning.
+
+## Contribution Types    
+Currently looking for help implementing new features or adding bug fixes. 
+
+A lot of good work has already been done in project mechanics (requirements.txt, setup.py, pep8, badges, ci, etc...) we're in a good state there thanks to all the early contributors (even pre-beta release)!   
+
+## Bug Fixes:  
+1. Submit a github issue.   
+2. Fix it.  
+3. Submit a PR! 
+
+## New Features:  
+1. Submit a github issue.   
+2. We'll agree on the feature scope.     
+3. Submit a PR! (with updated docs and tests 🙃).   
+
+## Coding Styleguide
+1. Test the code with flake8.
+2. Use f-strings.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,36 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: bug
+assignees: ''
+
+---
+
+### Common bugs:
+1. Tensorboard not showing in Jupyter-notebook see [issue 79](https://github.com/williamFalcon/pytorch-lightning/issues/79).    
+2. PyTorch 1.1.0 vs 1.2.0 support [see FAQ](https://github.com/williamFalcon/pytorch-lightning#faq)    
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. Scroll down to '....'
+4. See error
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**Desktop (please complete the following information):**
+ - OS: [e.g. iOS]
+ - Browser [e.g. chrome, safari]
+ - Version [e.g. 22]
+
+**Additional context**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,20 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: enhancement, help wanted
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/ISSUE_TEMPLATE/how-to-question.md

@@ -0,0 +1,26 @@
+---
+name: How to question
+about: Asking how-to questions
+title: ''
+labels: question
+assignees: ''
+
+---
+
+### Before asking:   
+1. search the issues.   
+2. search the docs.    
+
+If you still can't find what you need:     
+#### What is your question?    
+
+#### Code    
+Please paste a code snippet if your question requires it!   
+
+#### What have you tried?    
+
+#### What's your environment?   
+- conda version (no venv)   
+- PyTorch version   
+- Lightning version   
+- Test-tube version

.github/ISSUE_TEMPLATE/typos-and-doc-fixes.md

@@ -0,0 +1,17 @@
+---
+name: Typos and doc fixes
+about: Typos and doc fixes
+title: ''
+labels: typo
+assignees: ''
+
+---
+
+For typos and doc fixes, please go ahead and:
+
+1. Create an issue.
+2. Fix the typo.   
+3. Submit a PR.
+
+
+Thanks!

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,16 @@
+# Before submitting
+
+- Was this discussed/approved via a Github issue? (no need for typos, doc improvements)
+- Did you read the [contributor guideline](https://github.com/williamFalcon/pytorch-lightning/blob/master/.github/CONTRIBUTING.md)?
+- Did you make sure to update the docs?   
+- Did you write any new necessary tests?  
+
+## What does this PR do?
+Fixes # (issue).
+
+## PR review    
+Anyone in the community is free to review the PR once the tests have passed.     
+If we didn't discuss your PR in Github issues there's a high chance it will not be merged.   
+
+## Did you have fun?
+Make sure you had fun coding 🙃

.gitignore

@@ -10,6 +10,10 @@ app/models/
 pip-wheel-metadata/
 test_tube_exp/
 tests/tests_tt_dir/
+tests/save_dir
+default/
+lightning_logs/
+tests/tests/
 
 # Byte-compiled / optimized / DLL files
 __pycache__/

.readthedocs.yml

@@ -16,4 +16,4 @@ formats: all
 python:
   version: 3.7
   install:
-    - requirements: docs/doc_requirements.txt
+    - requirements: docs/requirements.txt

.run_local_tests.sh

@@ -0,0 +1,8 @@
+# use this to run tests
+rm -rf _ckpt_*
+rm -rf tests/save_dir*
+rm -rf tests/mlruns_*
+rm -rf tests/tests/*
+rm -rf lightning_logs
+coverage run --source pytorch_lightning -m py.test pytorch_lightning tests pl_examples -v --doctest-modules
+coverage report -m

.travis.yml

@@ -1,16 +1,69 @@
+# vim ft=yaml
+
+# After changing this file, check it on:
+#   http://yaml-online-parser.appspot.com/
+
+# See doc/travis_notes.txt for some guidelines
+
+# this file is *not* meant to cover or endorse the use of travis, but rather to
+# help confirm pull requests to this project.
+
+env:
+  global:
+    - DISPLAY=""
+
 language: python
-python:
-  - "3.7"
-# command to install dependencies
+
+matrix:
+  include:
+    - os: linux
+      dist: xenial  # Ubuntu 16.04
+      python: 3.6
+      env: TOXENV=py36
+    - os: linux
+      dist: bionic  # Ubuntu 18.04
+      python: 3.6
+      env: TOXENV=py36
+    - os: linux
+      dist: bionic  # Ubuntu 18.04
+      python: 3.7
+      env: TOXENV=py37
+    - os: osx
+      osx_image: xcode9.4
+      language: generic
+      env: TOXENV=py36
+      addons:
+        homebrew:
+          # update: true
+          packages: python3.6
+      before_install:
+        - pip3 install virtualenv
+        - virtualenv -p python3 ~/venv
+        - source ~/venv/bin/activate
+#    - os: windows
+#      language: minimal
+#      before_install:
+#        - choco install python3
+#        - export PATH="/c/Python37:/c/Python37/Scripts:$PATH"
+#      env: TOXENV=py37
+
+# See http://docs.travis-ci.com/user/caching/#pip-cache
 cache: pip
+
 install:
-  - pip install -e .
-  - pip install -r requirements.txt
-  - pip install -U numpy
+  - pip install future  # needed for `builtins`
+  - sudo pip install tox
 
-# keep build from timing out
-dist: xenial
-
-# command to run tests
 script:
-  - py.test # or py.test for Python versions 3.5 and below
+  # integration
+  - tox --sitepackages
+  - pip install --editable .
+
+after_success:
+  - coverage report
+  # disable auto coverage bc it isn't accurate since it misses gpu code.
+  # to get coverage, run local and push results
+  # - codecov
+
+notifications:
+  email: false

COPYING

@@ -1,21 +0,0 @@
-MIT License
-
-Copyright (c) 2019 William Falcon
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.

LICENSE

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
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+
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+
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+
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+
+      To apply the Apache License to your work, attach the following
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+
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+   limitations under the License.

MANIFEST.in

@@ -1,9 +1,42 @@
-graft docs
+# Manifest syntax https://docs.python.org/2/distutils/sourcedist.html
+graft wheelhouse
 
-include COPYING
-include AUTHORS
+recursive-include birl *.py
+recursive-exclude __pycache__  *.py[cod] *.orig
 
-recursive-include src/einsteinpy/tests *.py *.html
+# Include the README
+include *.md
 
-prune docs/source/examples/.ipynb_checkpoints
-global-exclude *.py[cod] __pycache__ *.so *.dylib
+# Include the license file
+include LICENSE
+
+exclude *.sh
+exclude *.toml
+exclude *.svg    
+recursive-include pytorch_lightning *.py
+
+# include examples
+recursive-include pl_examples *.py
+recursive-include pl_examples *.md
+recursive-include pl_examples *.sh
+
+# exclude tests from package
+recursive-exclude tests *
+recursive-exclude site *
+exclude tests
+
+# Exclude the documentation files
+recursive-exclude docs *
+exclude docs
+
+# Include the Requirements
+include requirements.txt
+
+# Exclude build configs
+exclude *.yml
+
+prune .git
+prune .github
+prune notebook*
+prune temp*
+prune test*

README.md

@@ -1,24 +1,32 @@
-<p align="center">
-  <a href="https://williamfalcon.github.io/pytorch-lightning/">
-    <img alt="" src="https://github.com/williamFalcon/pytorch-lightning/blob/master/docs/source/_static/lightning_logo.png" width="50">
-  </a>
-</p>
-<h3 align="center">
-  Pytorch Lightning
-</h3>
-<p align="center">
-  The Keras for ML researchers using PyTorch. More control. Less boilerplate.    
-</p>
+<div align="center">
 
-<p align="center">
-  <a href="https://badge.fury.io/py/pytorch-lightning"><img src="https://badge.fury.io/py/pytorch-lightning.svg" alt="PyPI version" height="18"></a>
-  <a href="https://pepy.tech/project/pytorch-lightning"><img src="https://pepy.tech/badge/pytorch-lightning" alt="PyPI version" height="18"></a>
-  <a href="https://github.com/williamFalcon/pytorch-lightning/tree/master/tests"><img src="https://github.com/williamFalcon/pytorch-lightning/blob/master/coverage.svg"></a>
-  <a href="https://travis-ci.org/williamFalcon/pytorch-lightning"><img src="https://travis-ci.org/williamFalcon/pytorch-lightning.svg?branch=master"></a>
-  <a href="https://williamfalcon.github.io/pytorch-lightning/"><img src="https://readthedocs.org/projects/pytorch-lightning/badge/?version=latest"></a>
-  <a href="https://github.com/williamFalcon/pytorch-lightning/blob/master/COPYING"><img src="https://img.shields.io/badge/License-MIT-yellow.svg"></a>
-</p>   
+![Logo](./docs/source/_static/lightning_logo_small.png)
 
+# PyTorch Lightning
+
+**The lightweight PyTorch wrapper for ML researchers. Scale your models. Write less boilerplate.**
+
+
+[![PyPI Status](https://badge.fury.io/py/pytorch-lightning.svg)](https://badge.fury.io/py/pytorch-lightning)
+[![PyPI Status](https://pepy.tech/badge/pytorch-lightning)](https://pepy.tech/project/pytorch-lightning)
+[![Build Status](https://travis-ci.org/williamFalcon/pytorch-lightning.svg?branch=master)](https://travis-ci.org/williamFalcon/pytorch-lightning)
+[![Build status](https://ci.appveyor.com/api/projects/status/NEW-PROJECT-ID?svg=true)](https://ci.appveyor.com/project/williamFalcon/pytorch-lightning)
+[![Coverage](https://github.com/williamFalcon/pytorch-lightning/blob/master/docs/source/_static/coverage.svg)](https://github.com/williamFalcon/pytorch-lightning/tree/master/tests#running-coverage)
+[![CodeFactor](https://www.codefactor.io/repository/github/borda/pytorch-lightning/badge)](https://www.codefactor.io/repository/github/borda/pytorch-lightning)    
+
+[![ReadTheDocs](https://readthedocs.org/projects/pytorch-lightning/badge/?version=latest)](https://pytorch-lightning.readthedocs.io/en/latest)
+[![Gitter](https://badges.gitter.im/PyTorch-Lightning/community.svg)](https://gitter.im/PyTorch-Lightning/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
+[![license](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://github.com/williamFalcon/pytorch-lightning/blob/master/LICENSE)
+[![Next Release](https://img.shields.io/badge/Next%20Release-Nov%206-<COLOR>.svg)](https://shields.io/)
+
+<!-- 
+removed until codecov badge isn't empy. likely a config error showing nothing on master.
+[![codecov](https://codecov.io/gh/Borda/pytorch-lightning/branch/master/graph/badge.svg)](https://codecov.io/gh/Borda/pytorch-lightning)
+-->
+
+</div>
+
+Simple installation from PyPI
 ```bash
 pip install pytorch-lightning  
 ```
@@ -27,102 +35,163 @@ pip install pytorch-lightning
 **[View the docs here](https://williamfalcon.github.io/pytorch-lightning/)**
 
 ## What is it?  
-Lightning defers training and validation loop logic to you. It guarantees correct, modern best practices for the core training logic.
+Lightning is a very lightweight wrapper on PyTorch. This means you don't have to learn a new library. To use Lightning, simply refactor your research code into the [LightningModule](https://github.com/williamFalcon/pytorch-lightning#how-do-i-do-use-it) format and Lightning will automate the rest. Lightning guarantees tested, correct, modern best practices for the automated parts.
 
+## Starting a new project?   
+[Use our seed-project aimed at reproducibility!](https://github.com/williamFalcon/pytorch-lightning-conference-seed)     
 
 ## Why do I want to use lightning?
-When starting a new project the last thing you want to do is recode a training loop, model loading/saving, distributed training, when to validate, etc... You're likely to spend a long time ironing out all the bugs without even getting to the core of your research.
+Every research project starts the same, a model, a training loop, validation loop, etc. As your research advances, you're likely to need distributed training, 16-bit precision, checkpointing, gradient accumulation, etc.   
 
-With lightning, you guarantee those parts of your code work so you can focus on what the meat of the research: Data and training, validation loop logic. Don't worry about multiple gpus or speeding up your code, lightning will do that for you!
+Lightning sets up all the boilerplate state-of-the-art training for you so you can focus on the research.   
+
+---
+ 
+## README Table of Contents        
+- [How do I use it](https://github.com/williamFalcon/pytorch-lightning#how-do-i-do-use-it)     
+- [What lightning automates](https://github.com/williamFalcon/pytorch-lightning#what-does-lightning-control-for-me)    
+- [Tensorboard integration](https://github.com/williamFalcon/pytorch-lightning#tensorboard)    
+- [Lightning features](https://github.com/williamFalcon/pytorch-lightning#lightning-automates-all-of-the-following-each-is-also-configurable)    
+- [Examples](https://github.com/williamFalcon/pytorch-lightning#examples)    
+- [Tutorials](https://github.com/williamFalcon/pytorch-lightning#tutorials)
+- [Contributing](https://github.com/williamFalcon/pytorch-lightning/blob/master/.github/CONTRIBUTING.md)
+- [Bleeding edge install](https://github.com/williamFalcon/pytorch-lightning#bleeding-edge)   
+- [Lightning Design Principles](https://github.com/williamFalcon/pytorch-lightning#lightning-design-principles)   
+- [Asking for help](https://github.com/williamFalcon/pytorch-lightning#asking-for-help)
+- [FAQ](https://github.com/williamFalcon/pytorch-lightning#faq)    
+
+---
 
 ## How do I do use it?   
+Think about Lightning as refactoring your research code instead of using a new framework. The research code goes into a [LightningModule]((https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/)) which you fit using a Trainer.    
+
+The LightningModule defines a *system* such as seq-2-seq, GAN, etc... It can ALSO define a simple classifier such as the example below.     
 
 To use lightning do 2 things:  
-1. [Define a LightningModel](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/)         
+1. [Define a LightningModule](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/)     
+
+**WARNING:** This syntax is for version 0.5.0+ where abbreviations were removed.    
 ```python
-import pytorch_lightning as ptl
+import os
 import torch
 from torch.nn import functional as F
 from torch.utils.data import DataLoader
 from torchvision.datasets import MNIST
+import torchvision.transforms as transforms
 
-class CoolModel(ptl.LightningModule):
+import pytorch_lightning as pl
 
-    def __init(self):
-        super(CoolModel, self).__init__()
+class CoolSystem(pl.LightningModule):
+
+    def __init__(self):
+        super(CoolSystem, self).__init__()
         # not the best model...
         self.l1 = torch.nn.Linear(28 * 28, 10)
 
     def forward(self, x):
-        return torch.relu(self.l1(x))
-
-    def my_loss(self, y_hat, y):
-        return F.cross_entropy(y_hat, y)
+        return torch.relu(self.l1(x.view(x.size(0), -1)))
 
     def training_step(self, batch, batch_nb):
+        # REQUIRED
         x, y = batch
         y_hat = self.forward(x)
-        return {'tng_loss': self.my_loss(y_hat, y)}
+        loss = F.cross_entropy(y_hat, y)
+        tensorboard_logs = {'train_loss': loss}
+        return {'loss': loss, 'log': tensorboard_logs}
 
     def validation_step(self, batch, batch_nb):
+        # OPTIONAL
         x, y = batch
         y_hat = self.forward(x)
-        return {'val_loss': self.my_loss(y_hat, y)}
+        return {'val_loss': F.cross_entropy(y_hat, y)}
 
     def validation_end(self, outputs):
-        avg_loss = torch.stack([x for x in outputs['val_loss']]).mean()
-        return avg_loss
+        # OPTIONAL
+        avg_loss = torch.stack([x['val_loss'] for x in outputs]).mean()
+        tensorboard_logs = {'val_loss': avg_loss}
+        return {'avg_val_loss': avg_loss, 'log': tensorboard_logs}
 
     def configure_optimizers(self):
-        return [torch.optim.Adam(self.parameters(), lr=0.02)]
+        # REQUIRED
+        # can return multiple optimizers and learning_rate schedulers
+        # (LBFGS it is automatically supported, no need for closure function)
+        return torch.optim.Adam(self.parameters(), lr=0.02)
 
-    @ptl.data_loader
-    def tng_dataloader(self):
-        return DataLoader(MNIST('path/to/save', train=True), batch_size=32)
+    @pl.data_loader
+    def train_dataloader(self):
+        # REQUIRED
+        return DataLoader(MNIST(os.getcwd(), train=True, download=True, transform=transforms.ToTensor()), batch_size=32)
 
-    @ptl.data_loader
+    @pl.data_loader
     def val_dataloader(self):
-        return DataLoader(MNIST('path/to/save', train=False), batch_size=32)
+        # OPTIONAL
+        return DataLoader(MNIST(os.getcwd(), train=True, download=True, transform=transforms.ToTensor()), batch_size=32)
 
-    @ptl.data_loader
+    @pl.data_loader
     def test_dataloader(self):
-        return DataLoader(MNIST('path/to/save', train=False), batch_size=32)
+        # OPTIONAL
+        return DataLoader(MNIST(os.getcwd(), train=False, download=True, transform=transforms.ToTensor()), batch_size=32)
 ```
-
 2. Fit with a [trainer](https://williamfalcon.github.io/pytorch-lightning/Trainer/)    
 ```python
 from pytorch_lightning import Trainer
-from test_tube import Experiment
 
-model = CoolModel()
+model = CoolSystem()
 
-# fit on 32 gpus across 4 nodes
-exp = Experiment(save_dir='some/dir')
-trainer = Trainer(experiment=exp, nb_gpu_nodes=4, gpus=[0,1,2,3,4,5,6,7])
+# most basic trainer, uses good defaults
+trainer = Trainer()    
+trainer.fit(model)   
+```     
 
+Trainer sets up a tensorboard logger, early stopping and checkpointing by default (you can modify all of them or
+use something other than tensorboard).   
+
+Here are more advanced examples
+```python   
+# train on cpu using only 10% of the data (for demo purposes)
+trainer = Trainer(max_nb_epochs=1, train_percent_check=0.1)
+
+# train on 4 gpus (lightning chooses GPUs for you)
+# trainer = Trainer(max_nb_epochs=1, gpus=4, distributed_backend='ddp')  
+
+# train on 4 gpus (you choose GPUs)
+# trainer = Trainer(max_nb_epochs=1, gpus=[0, 1, 3, 7], distributed_backend='ddp')   
+
+# train on 32 gpus across 4 nodes (make sure to submit appropriate SLURM job)
+# trainer = Trainer(max_nb_epochs=1, gpus=8, nb_gpu_nodes=4, distributed_backend='ddp')
+
+# train (1 epoch only here for demo)
 trainer.fit(model)
 
-# see all experiment metrics here
-# tensorboard --log_dir some/dir   
+# view tensorboard logs 
+logging.info(f'View tensorboard logs by running\ntensorboard --logdir {os.getcwd()}')
+logging.info('and going to http://localhost:6006 on your browser')
+```    
+
+When you're all done you can even run the test set separately.   
+```python
+trainer.test()
 ```
 
+## What does lightning control for me?   
 
-## What does lightning control for me?
-Everything!    
-Except for these 6 core functions which you define:    
+Everything in gray!    
+You define the blue parts using the LightningModule interface:  
 
-```{.python}
+![Overview](./docs/source/_static/overview_flat.jpg)
+
+```python
 # what to do in the training loop
-def training_step(self, data_batch, batch_nb):
+def training_step(self, batch, batch_nb):
 
 # what to do in the validation loop
-def validation_step(self, data_batch, batch_nb):
+def validation_step(self, batch, batch_nb):
 
 # how to aggregate validation_step outputs
 def validation_end(self, outputs):
 
 # and your dataloaders
-def tng_dataloader():
+def train_dataloader():
 def val_dataloader():
 def test_dataloader():
 ```
@@ -131,13 +200,13 @@ def test_dataloader():
 
 ```python
 # define what happens for training here
-def training_step(self, data_batch, batch_nb):
-    x, y = data_batch
+def training_step(self, batch, batch_nb):
+    x, y = batch
     
     # define your own forward and loss calculation
     hidden_states = self.encoder(x)
      
-    # even as complex as a seq-2seq + attn model
+    # even as complex as a seq-2-seq + attn model
     # (this is just a toy, non-working example to illustrate)
     start_token = '<SOS>'
     last_hidden = torch.zeros(...)
@@ -158,8 +227,8 @@ def training_step(self, data_batch, batch_nb):
 
 ```python
 # define what happens for validation here
-def validation_step(self, data_batch, batch_nb):    
-    x, y = data_batch
+def validation_step(self, batch, batch_nb):    
+    x, y = batch
     
     # or as basic as a CNN classification
     out = self.forward(x)
@@ -184,66 +253,48 @@ def validation_end(self, outputs):
 
     val_loss_mean /= len(outputs)
     val_acc_mean /= len(outputs)
-    tqdm_dic = {'val_loss': val_loss_mean.item(), 'val_acc': val_acc_mean.item()}
-    return tqdm_dic
+    logs = {'val_loss': val_loss_mean.item(), 'val_acc': val_acc_mean.item()}
+    result = {'log': logs}
+    return result
 ```
    
 ## Tensorboard    
-Lightning is fully integrated with tensorboard.   
+Lightning is fully integrated with tensorboard, MLFlow and supports any logging module.   
 
-<p align="center">
-  <a href="https://williamfalcon.github.io/pytorch-lightning/">
-    <img alt="" src="https://github.com/williamFalcon/pytorch-lightning/blob/master/docs/source/_static/tf_loss.png" width="900px">
-  </a>
-</p>
+![tensorboard-support](./docs/source/_static/tf_loss.png)
 
 Lightning also adds a text column with all the hyperparameters for this experiment.      
 
-<p align="center">
-  <a href="https://williamfalcon.github.io/pytorch-lightning/">
-        <img alt="" src="https://github.com/williamFalcon/pytorch-lightning/blob/master/docs/source/_static/tf_tags.png" width="900px">
-  </a>
-</p>
-
-Simply note the path you set for the Experiment    
-``` {.python}   
-from test_tube import Experiment
-from pytorch-lightning import  Trainer
-
-exp = Experiment(save_dir='/some/path')
-trainer = Trainer(experiment=exp)
-...
-```   
-
-And run tensorboard from that dir   
-```bash
-tensorboard --logdir /some/path     
-```    
+![tensorboard-support](./docs/source/_static/tf_tags.png)
 
 ## Lightning automates all of the following ([each is also configurable](https://williamfalcon.github.io/pytorch-lightning/Trainer/)):
 
-###### Checkpointing    
+#### Checkpointing    
 
+- [Checkpoint callback](https://williamfalcon.github.io/pytorch-lightning/Trainer/Checkpointing/#model-saving)
 - [Model saving](https://williamfalcon.github.io/pytorch-lightning/Trainer/Checkpointing/#model-saving)
 - [Model loading](https://williamfalcon.github.io/pytorch-lightning/LightningModule/methods/#load-from-metrics) 
+- [Restoring training session](https://williamfalcon.github.io/pytorch-lightning/Trainer/Checkpointing/#restoring-training-session)
 
-###### Computing cluster (SLURM)    
+#### Computing cluster (SLURM)    
 
 - [Running grid search on a cluster](https://williamfalcon.github.io/pytorch-lightning/Trainer/SLURM%20Managed%20Cluster#running-grid-search-on-a-cluster) 
 - [Walltime auto-resubmit](https://williamfalcon.github.io/pytorch-lightning/Trainer/SLURM%20Managed%20Cluster#walltime-auto-resubmit)   
 
-###### Debugging  
+#### Debugging  
 
 - [Fast dev run](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#fast-dev-run)
 - [Inspect gradient norms](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#inspect-gradient-norms)
 - [Log GPU usage](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#Log-gpu-usage)
 - [Make model overfit on subset of data](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#make-model-overfit-on-subset-of-data)
 - [Print the parameter count by layer](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#print-the-parameter-count-by-layer)
-- [Pring which gradients are nan](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#print-which-gradients-are-nan)
+- [Print which gradients are nan](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#print-which-gradients-are-nan)
+- [Print input and output size of every module in system](https://williamfalcon.github.io/pytorch-lightning/LightningModule/properties/#example_input_array)
 
 
-###### Distributed training    
+#### Distributed training    
 
+- [Implement Your Own Distributed (DDP) training](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/#init_ddp_connection)
 - [16-bit mixed precision](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#16-bit-mixed-precision)
 - [Multi-GPU](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#Multi-GPU)
 - [Multi-node](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#Multi-node)
@@ -251,58 +302,132 @@ tensorboard --logdir /some/path
 - [Self-balancing architecture](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#self-balancing-architecture)
 
 
-###### Experiment Logging   
+#### Experiment Logging   
 
 - [Display metrics in progress bar](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#display-metrics-in-progress-bar)
-- Log arbitrary metrics
 - [Log metric row every k batches](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#log-metric-row-every-k-batches)
 - [Process position](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#process-position)
+- [Tensorboard support](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#tensorboard-support)
 - [Save a snapshot of all hyperparameters](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#save-a-snapshot-of-all-hyperparameters) 
 - [Snapshot code for a training run](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#snapshot-code-for-a-training-run) 
 - [Write logs file to csv every k batches](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#write-logs-file-to-csv-every-k-batches)
 
-###### Training loop    
+#### Training loop    
 
 - [Accumulate gradients](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#accumulated-gradients)
-- [Anneal Learning rate](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#anneal-learning-rate)
 - [Force training for min or max epochs](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#force-training-for-min-or-max-epochs)
+- [Early stopping callback](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#early-stopping)
 - [Force disable early stop](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#force-disable-early-stop)
 - [Gradient Clipping](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#gradient-clipping)
-- [Use multiple optimizers (like GANs)](https://williamfalcon.github.io/pytorch-lightning/Pytorch-Lightning/LightningModule/#configure_optimizers)
+- [Hooks](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/)
+- [Learning rate scheduling](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/#configure_optimizers)    
+- [Use multiple optimizers (like GANs)](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/#configure_optimizers)
 - [Set how much of the training set to check (1-100%)](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#set-how-much-of-the-training-set-to-check)
+- [Step optimizers at arbitrary intervals](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/#optimizer_step)
 
-###### Validation loop    
+#### Validation loop    
 
 - [Check validation every n epochs](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#check-validation-every-n-epochs)
+- [Hooks](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/)
 - [Set how much of the validation set to check](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-how-much-of-the-validation-set-to-check)
 - [Set how much of the test set to check](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-how-much-of-the-test-set-to-check)
 - [Set validation check frequency within 1 training epoch](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-validation-check-frequency-within-1-training-epoch)
 - [Set the number of validation sanity steps](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-the-number-of-validation-sanity-steps)
 
+#### Testing loop  
+- [Run test set](https://williamfalcon.github.io/pytorch-lightning/Trainer/Testing%20loop/)  
 
-## Demo
+## Examples   
+- [GAN](https://github.com/williamFalcon/pytorch-lightning/tree/master/pl_examples/domain_templates/gan.py)    
+- [MNIST](https://github.com/williamFalcon/pytorch-lightning/tree/master/pl_examples/basic_examples)      
+- [Other projects using Lightning](https://github.com/williamFalcon/pytorch-lightning/network/dependents?package_id=UGFja2FnZS0zNzE3NDU4OTM%3D)    
+- [Multi-node](https://github.com/williamFalcon/pytorch-lightning/tree/master/pl_examples/multi_node_examples)   
+
+## Tutorials   
+- [Basic Lightning use](https://towardsdatascience.com/supercharge-your-ai-research-with-pytorch-lightning-337948a99eec)    
+- [9 key speed features in Pytorch-Lightning](https://towardsdatascience.com/9-tips-for-training-lightning-fast-neural-networks-in-pytorch-8e63a502f565)    
+- [SLURM, multi-node training with Lightning](https://towardsdatascience.com/trivial-multi-node-training-with-pytorch-lightning-ff75dfb809bd)     
+
+---    
+## Asking for help    
+Welcome to the Lightning community!   
+
+If you have any questions, feel free to:   
+1. [read the docs](https://williamfalcon.github.io/pytorch-lightning/).     
+2. [Search through the issues](https://github.com/williamFalcon/pytorch-lightning/issues?utf8=%E2%9C%93&q=my++question).      
+3. [Ask on stackoverflow](https://stackoverflow.com/questions/ask?guided=false) with the tag pytorch-lightning.   
+
+If no one replies to you quickly enough, feel free to post the stackoverflow link to our Gitter chat!   
+
+To chat with the rest of us visit our [gitter channel](https://gitter.im/PyTorch-Lightning/community)!     
+
+---   
+## FAQ    
+**How do I use Lightning for rapid research?**   
+[Here's a walk-through](https://williamfalcon.github.io/pytorch-lightning/)  
+
+**Why was Lightning created?**     
+Lightning has 3 goals in mind:
+1. Maximal flexibility while abstracting out the common boilerplate across research projects.   
+2. Reproducibility. If all projects use the LightningModule template, it will be much much easier to understand what's going on and where to look! It will also mean every implementation follows a standard format.   
+3. Democratizing PyTorch power user features. Distributed training? 16-bit? know you need them but don't want to take the time to implement? All good... these come built into Lightning.    
+
+**How does Lightning compare with Ignite and fast.ai?**     
+[Here's a thorough comparison](https://medium.com/@_willfalcon/pytorch-lightning-vs-pytorch-ignite-vs-fast-ai-61dc7480ad8a).    
+
+**Is this another library I have to learn?**    
+Nope! We use pure Pytorch everywhere and don't add unecessary abstractions!   
+
+**Are there plans to support Python 2?**          
+Nope.     
+
+**Are there plans to support virtualenv?**    
+Nope. Please use anaconda or miniconda.    
+
+**Which PyTorch versions do you support?**    
+- **PyTorch 1.1.0**       
+    ```bash    
+    # install pytorch 1.1.0 using the official instructions   
+    
+    # install test-tube 0.6.7.6 which supports 1.1.0   
+    pip install test-tube==0.6.7.6   
+    
+    # install latest Lightning version without upgrading deps    
+    pip install -U --no-deps pytorch-lightning
+    ```     
+- **PyTorch 1.2.0, 1.3.0,**
+    Install via pip as normal   
+
+## Custom installation
+
+### Bleeding edge
+
+If you can't wait for the next release, install the most up to date code with:
+* using GIT (locally clone whole repo with full history)
+    ```bash
+    pip install git+https://github.com/williamFalcon/pytorch-lightning.git@master --upgrade
+    ```
+* using instant zip (last state of the repo without git history)
+    ```bash
+    pip install https://github.com/williamFalcon/pytorch-lightning/archive/master.zip --upgrade
+    ```
+
+### Any release installation
+
+You can also install any past release from this repository:
 ```bash
-# install lightning
-pip install pytorch-lightning
-
-# clone lightning for the demo
-git clone https://github.com/williamFalcon/pytorch-lightning.git
-cd pytorch_lightning/examples/new_project_templates/
-
-# all of the following demos use the SAME model to show no modification needs to be made to your code
-
-# train on cpu 
-python single_cpu_template.py
-
-# train on multiple-gpus 
-python single_gpu_node_template.py --gpus "0,1"
-
-# train on 32 gpus on a cluster (run on a SLURM managed cluster)
-python multi_node_cluster_template.py --nb_gpu_nodes 4 --gpus '0,1,2,3,4,5,6,7'
+pip install https://github.com/williamFalcon/pytorch-lightning/archive/0.4.4.zip --upgrade
 ```
 
-## Bleeding edge
-If you can't wait for the next release, install the most up to date code with:  
-```bash
-pip install git+https://github.com/williamFalcon/pytorch-lightning.git@master --upgrade
-```
+## Bibtex
+If you want to cite the framework feel free to use this (but only if you loved it 😊):
+```
+@misc{Falcon2019,
+  author = {Falcon, W.A.},
+  title = {PyTorch Lightning},
+  year = {2019},
+  publisher = {GitHub},
+  journal = {GitHub repository},
+  howpublished = {\url{https://github.com/williamFalcon/pytorch-lightning}}
+}
+```

appveyor.yml

@@ -0,0 +1,64 @@
+# https://www.appveyor.com/docs/appveyor-yml/
+environment:
+
+  # SDK v7.0 MSVC Express 2008's SetEnv.cmd script will fail if the
+  # /E:ON and /V:ON options are not enabled in the batch script interpreter
+  # See: http://stackoverflow.com/a/13751649/163740
+  CMD_IN_ENV: "cmd /E:ON /V:ON /C obvci_appveyor_python_build_env.cmd"
+
+  matrix:
+    # Pre-installed Python versions, which Appveyor may upgrade to
+    # a later point release.
+    # See: http://www.appveyor.com/docs/installed-software#python
+
+
+    # - PYTHON: "C:\\Python35-x64"
+    #   PYTHON_VERSION: "3.5.x"
+    #   PYTHON_ARCH: "64"
+    #  TOXENV: "py35"
+
+    - PYTHON: "C:\\Python36-x64"
+      PYTHON_VERSION: "3.6.x"
+      PYTHON_ARCH: "64"
+      TOXENV: "py36"
+      PIP_PYVER: "36"
+
+    - PYTHON: "C:\\Python37-x64"
+      PYTHON_VERSION: "3.7.x"
+      PYTHON_ARCH: "64"
+      TOXENV: "py37"
+      PIP_PYVER: "37"
+
+build: off
+
+# https://www.appveyor.com/docs/build-cache/
+cache:
+  - C:\ProgramData\chocolatey\bin -> appveyor.yml
+  - C:\ProgramData\chocolatey\lib -> appveyor.yml
+  - '%LOCALAPPDATA%\pip\Cache -> appveyor.yml'
+
+# scripts that run after cloning repository
+install:
+  # If there is a newer build queued for the same PR, cancel this one.
+  # The AppVeyor 'rollout builds' option is supposed to serve the same
+  # purpose but it is problematic because it tends to cancel builds pushed
+  # directly to master instead of just PR builds (or the converse).
+  - SET PATH=%PYTHON%;%PYTHON%\\Scripts;%path%
+  - pip install -U --user pip
+  - pip install -r requirements.txt -f https://download.pytorch.org/whl/torch_stable.html
+  - pip install -r ./tests/requirements.txt
+
+# scripts to run before tests (working directory and environment changes are persisted from the previous steps such as "before_build")
+before_test:
+  - python --version
+  - pip --version
+  - pip list
+  - dir
+
+# to run your custom scripts instead of automatic tests
+test_script:
+  - tox --sitepackages --parallel auto
+
+on_success:
+  - coverage report
+  # - codecov

docs/LightningModule/RequiredTrainerInterface.md

@@ -3,87 +3,115 @@
 
 A lightning module is a strict superclass of nn.Module, it provides a standard interface for the trainer to interact with the model.
 
-The easiest thing to do is copy [this template](../../pytorch_lightning/examples/new_project_templates/lightning_module_template.py) and modify accordingly. 
+The easiest thing to do is copy the [minimal example](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/#minimal-example) below and modify accordingly. 
 
 Otherwise, to Define a Lightning Module, implement the following methods:
 
 **Required**:  
 
-- [training_step](RequiredTrainerInterface.md#training_step)   
-- [validation_step](RequiredTrainerInterface.md#validation_step)
-- [validation_end](RequiredTrainerInterface.md#validation_end)
-    
-- [configure_optimizers](RequiredTrainerInterface.md#configure_optimizers)
-- [get_save_dict](RequiredTrainerInterface.md#get_save_dict)
-- [load_model_specific](RequiredTrainerInterface.md#load_model_specific)
-
-- [tng_dataloader](RequiredTrainerInterface.md#tng_dataloader)
-- [tng_dataloader](RequiredTrainerInterface.md#tng_dataloader)
-- [test_dataloader](RequiredTrainerInterface.md#test_dataloader)
+- [training_step](RequiredTrainerInterface.md#training_step)      
+- [train_dataloader](RequiredTrainerInterface.md#train_dataloader)    
+- [configure_optimizers](RequiredTrainerInterface.md#configure_optimizers)    
 
 **Optional**:   
 
-- [update_tng_log_metrics](RequiredTrainerInterface.md#update_tng_log_metrics)
-- [add_model_specific_args](RequiredTrainerInterface.md#add_model_specific_args)
+- [training_end](RequiredTrainerInterface.md#training_end)      
+- [validation_step](RequiredTrainerInterface.md#validation_step)    
+- [validation_end](RequiredTrainerInterface.md#validation_end) 
+- [test_step](RequiredTrainerInterface.md#test_step)    
+- [test_end](RequiredTrainerInterface.md#test_end) 
+- [val_dataloader](RequiredTrainerInterface.md#val_dataloader)    
+- [test_dataloader](RequiredTrainerInterface.md#test_dataloader)    
+- [on_save_checkpoint](RequiredTrainerInterface.md#on_save_checkpoint)    
+- [on_load_checkpoint](RequiredTrainerInterface.md#on_load_checkpoint)    
+- [add_model_specific_args](RequiredTrainerInterface.md#add_model_specific_args)    
 
 ---
-**Minimal example**
+### Minimal example   
 ```python
-import pytorch_lightning as ptl
+import os
 import torch
 from torch.nn import functional as F
 from torch.utils.data import DataLoader
 from torchvision.datasets import MNIST
+import torchvision.transforms as transforms
 
-class CoolModel(ptl.LightningModule):
+import pytorch_lightning as pl
 
-    def __init(self):
+class CoolModel(pl.LightningModule):
+
+    def __init__(self):
         super(CoolModel, self).__init__()
         # not the best model...
         self.l1 = torch.nn.Linear(28 * 28, 10)
 
     def forward(self, x):
-        return torch.relu(self.l1(x))
-
-    def my_loss(self, y_hat, y):
-        return F.cross_entropy(y_hat, y)
+        return torch.relu(self.l1(x.view(x.size(0), -1)))
 
     def training_step(self, batch, batch_nb):
+        # REQUIRED
         x, y = batch
         y_hat = self.forward(x)
-        return {'tng_loss': self.my_loss(y_hat, y)}
+        return {'loss': F.cross_entropy(y_hat, y)}
 
     def validation_step(self, batch, batch_nb):
+        # OPTIONAL
         x, y = batch
         y_hat = self.forward(x)
-        return {'val_loss': self.my_loss(y_hat, y)}
+        return {'val_loss': F.cross_entropy(y_hat, y)}
 
     def validation_end(self, outputs):
-        avg_loss = torch.stack([x for x in outputs['val_loss']]).mean()
-        return avg_loss
+        # OPTIONAL
+        avg_loss = torch.stack([x['val_loss'] for x in outputs]).mean()
+        return {'avg_val_loss': avg_loss}
+
+    def test_step(self, batch, batch_nb):
+        # OPTIONAL
+        x, y = batch
+        y_hat = self.forward(x)
+        return {'test_loss': F.cross_entropy(y_hat, y)}
+
+    def test_end(self, outputs):
+        # OPTIONAL
+        avg_loss = torch.stack([x['test_loss'] for x in outputs]).mean()
+        return {'avg_test_loss': avg_loss}
 
     def configure_optimizers(self):
-        return [torch.optim.Adam(self.parameters(), lr=0.02)]
+        # REQUIRED
+        return torch.optim.Adam(self.parameters(), lr=0.02)
 
-    @ptl.data_loader
-    def tng_dataloader(self):
-        return DataLoader(MNIST('path/to/save', train=True), batch_size=32)
+    @pl.data_loader
+    def train_dataloader(self):
+        return DataLoader(MNIST(os.getcwd(), train=True, download=True, transform=transforms.ToTensor()), batch_size=32)
 
-    @ptl.data_loader
+    @pl.data_loader
     def val_dataloader(self):
-        return DataLoader(MNIST('path/to/save', train=False), batch_size=32)
+        # OPTIONAL
+        # can also return a list of val dataloaders
+        return DataLoader(MNIST(os.getcwd(), train=True, download=True, transform=transforms.ToTensor()), batch_size=32)
 
-    @ptl.data_loader
+    @pl.data_loader
     def test_dataloader(self):
-        return DataLoader(MNIST('path/to/save', train=False), batch_size=32)
+        # OPTIONAL
+        # can also return a list of test dataloaders
+        return DataLoader(MNIST(os.getcwd(), train=False, download=True, transform=transforms.ToTensor()), batch_size=32)
 ```
+---   
+### How do these methods fit into the broader training?     
+The LightningModule interface is on the right. Each method corresponds to a part of a research project. Lightning automates everything not in blue.    
 
----
+<p align="center">
+  <a href="https://github.com/williamFalcon/pytorch-lightning/blob/master/docs/source/_static/overview_flat.jpg">
+    <img alt="" src="https://github.com/williamFalcon/pytorch-lightning/blob/master/docs/source/_static/overview_flat.jpg" height="900px">
+  </a>
+</p>   
+
+## Required Methods    
 
 ### training_step
 
 ``` {.python}
-def training_step(self, data_batch, batch_nb)
+def training_step(self, batch, batch_nb)
 ```
 
 In this step you'd normally do the forward pass and calculate the loss for a batch. You can also do fancier things like multiple forward passes or something specific to your model.
@@ -92,7 +120,7 @@ In this step you'd normally do the forward pass and calculate the loss for a bat
 
 | Param  | description  |
 |---|---|
-|  data_batch | The output of your dataloader. A tensor, tuple or list  |
+|  batch | The output of your dataloader. A tensor, tuple or list  |
 |  batch_nb | Integer displaying which batch this is  |
 
 **Return**   
@@ -102,61 +130,258 @@ Dictionary or OrderedDict
 | key  | value  | is required |
 |---|---|---|
 |  loss | tensor scalar  | Y |
-|  prog | Dict for progress bar display. Must have only tensors  | N |
+|  progress_bar | Dict for progress bar display. Must have only tensors  | N |
+|  log | Dict of metrics to add to logger. Must have only tensors (no images, etc)  | N |
 
 
 **Example**
 
 ``` {.python}
-def training_step(self, data_batch, batch_nb):
-    x, y, z = data_batch
+def training_step(self, batch, batch_nb):
+    x, y, z = batch
     
     # implement your own
     out = self.forward(x)
     loss = self.loss(out, x)
     
+    logger_logs = {'training_loss': loss} # optional (MUST ALL BE TENSORS)
+    
+    # if using TestTubeLogger or TensorboardLogger you can nest scalars
+    logger_logs = {'losses': logger_logs} # optional (MUST ALL BE TENSORS)
+    
     output = {
         'loss': loss, # required
-        'prog': {'tng_loss': loss, 'batch_nb': batch_nb} # optional
+        'progress_bar': {'training_loss': loss}, # optional (MUST ALL BE TENSORS)
+        'log': logger_logs
     }
     
     # return a dict
     return output
+```    
+
+If you define multiple optimizers, this step will also be called with an additional ```optimizer_idx``` param.    
+``` {.python}
+# Multiple optimizers (ie: GANs)     
+def training_step(self, batch, batch_nb, optimizer_idx):
+    if optimizer_idx == 0:
+        # do training_step with encoder
+    if optimizer_idx == 1:
+        # do training_step with decoder    
+```    
+
+If you add truncated back propagation through time you will also get an additional argument with the hidden states of the previous step.     
+``` {.python}
+# Truncated back-propagation through time   
+def training_step(self, batch, batch_nb, hiddens):
+    # hiddens are the hiddens from the previous truncated backprop step
+```    
+
+You can also return a -1 instead of a dict to stop the current loop. This is useful if you want to
+break out of the current training epoch early.
+
+---   
+### training_end
+
+``` {.python}
+def training_end(self, train_step_outputs)
+```
+In certain cases (dp, ddp2), you might want to use all outputs of every process to do something.
+For instance, if using negative samples, you could run a batch via dp and use ALL the outputs 
+for a single softmax across the full batch (ie: the denominator would use the full batch).
+
+In this case you should define training_end to perform those calculations.
+
+
+**Params**    
+
+| Param  | description  |
+|---|---|
+|  outputs | What you return in training_step. 
+
+**Return**   
+
+Dictionary or OrderedDict   
+
+| key  | value  | is required |
+|---|---|---|
+|  loss | tensor scalar  | Y |
+|  progress_bar | Dict for progress bar display. Must have only tensors  | N |
+|  log | Dict of metrics to add to logger. Must have only tensors (no images, etc)  | N |
+
+
+**Example**
+
+``` {.python}
+# WITHOUT training_end
+# if used in DP or DDP2, this batch is 1/nb_gpus large
+def training_step(self, batch, batch_nb):
+    # batch is 1/nb_gpus big
+    x, y = batch
+    
+    out = self.forward(x)
+    loss = self.softmax(out)
+    loss = nce_loss(loss)
+    return {'loss': loss}
+
+# --------------
+# with training_end to do softmax over the full batch
+def training_step(self, batch, batch_nb):
+    # batch is 1/nb_gpus big
+    x, y = batch
+    
+    out = self.forward(x)
+    return {'out': out}
+
+def training_end(self, outputs):
+    # this out is now the full size of the batch
+    out = outputs['out']
+
+    # this softmax now uses the full batch size
+    loss = self.softmax(out)
+    loss = nce_loss(loss)
+    return {'loss': loss}
+```    
+
+If you define multiple optimizers, this step will also be called with an additional ```optimizer_idx``` param.    
+``` {.python}
+# Multiple optimizers (ie: GANs)     
+def training_step(self, batch, batch_nb, optimizer_idx):
+    if optimizer_idx == 0:
+        # do training_step with encoder
+    if optimizer_idx == 1:
+        # do training_step with decoder    
+```    
+
+If you add truncated back propagation through time you will also get an additional argument with the hidden states of the previous step.     
+``` {.python}
+# Truncated back-propagation through time   
+def training_step(self, batch, batch_nb, hiddens):
+    # hiddens are the hiddens from the previous truncated backprop step
+```    
+
+You can also return a -1 instead of a dict to stop the current loop. This is useful if you want to
+break out of the current training epoch early.
+
+--- 
+### train_dataloader 
+
+``` {.python}
+@pl.data_loader
+def train_dataloader(self)
+```
+Called by lightning during training loop. Make sure to use the @pl.data_loader decorator, this ensures not calling this function until the data are needed.   
+If you want to change the data during every epoch DON'T use the data_loader decorator.
+
+##### Return
+PyTorch DataLoader
+
+**Example**
+
+``` {.python}
+@pl.data_loader
+def train_dataloader(self):
+    transform = transforms.Compose([transforms.ToTensor(), transforms.Normalize((0.5,), (1.0,))])
+    dataset = MNIST(root='/path/to/mnist/', train=True, transform=transform, download=True)
+    loader = torch.utils.data.DataLoader(
+        dataset=dataset,
+        batch_size=self.hparams.batch_size,
+        shuffle=True
+    )
+    return loader
 ```
 
----
+--- 
+### configure_optimizers 
+
+``` {.python}
+def configure_optimizers(self)
+```
+
+Set up as many optimizers and (optionally) learning rate schedulers as you need. Normally you'd need one. But in the case of GANs or something more esoteric you might have multiple. 
+Lightning will call .backward() and .step() on each one in every epoch.  If you use 16 bit precision it will also handle that.
+
+**Note:** If you use multiple optimizers, training_step will have an additional ```optimizer_idx``` parameter.    
+**Note 2:** If you use LBFGS lightning handles the closure function automatically for you.
+
+##### Return    
+Return any of these 3 options:   
+Single optimizer   
+List or Tuple - List of optimizers    
+Two lists - The first list has multiple optimizers, the second a list of learning-rate schedulers
+
+**Example**
+
+``` {.python}
+# most cases
+def configure_optimizers(self):
+    opt = Adam(self.parameters(), lr=0.01)
+    return opt
+
+# multiple optimizer case (eg: GAN)
+def configure_optimizers(self):
+    generator_opt = Adam(self.model_gen.parameters(), lr=0.01)
+    disriminator_opt = Adam(self.model_disc.parameters(), lr=0.02)
+    return generator_opt, disriminator_opt
+    
+# example with learning_rate schedulers  
+def configure_optimizers(self):
+    generator_opt = Adam(self.model_gen.parameters(), lr=0.01)
+    disriminator_opt = Adam(self.model_disc.parameters(), lr=0.02)
+    discriminator_sched = CosineAnnealing(discriminator_opt, T_max=10)
+    return [generator_opt, disriminator_opt], [discriminator_sched]
+```  
+
+If you need to control how often those optimizers step or override the default .step() schedule, override 
+the [optimizer_step](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/#optimizer_step) hook.   
+
+## Optional Methods    
 
 ### validation_step
 
 ``` {.python}
-def validation_step(self, data_batch, batch_nb)
-```
+# if you have one val dataloader:
+def validation_step(self, batch, batch_nb)   
 
-In this step you'd normally do the forward pass and calculate the loss for a batch. You can also do fancier things like multiple forward passes or something specific to your model.
-This is most likely the same as your training_step. But unlike training step, the outputs from here will go to validation_end for collation.
+# if you have multiple val dataloaders:  
+def validation_step(self, batch, batch_nb, dataloader_idxdx)
+```
+**OPTIONAL**    
+If you don't need to validate you don't need to implement this method. In this step you'd normally generate examples or calculate anything of interest such as accuracy. 
+
+When the validation_step is called, the model has been put in eval mode and PyTorch gradients have been disabled. At the end of validation, model goes back to training mode and gradients are enabled.
+
+The dict you return here will be available in the `validation_end` method. 
 
 **Params**   
 
 | Param  | description  |
 |---|---|
-|  data_batch | The output of your dataloader. A tensor, tuple or list  |
+|  batch | The output of your dataloader. A tensor, tuple or list  |
 |  batch_nb | Integer displaying which batch this is  |
+|  dataloader_idx | Integer displaying which dataloader this is (only if multiple val datasets used)  |
 
 **Return**   
 
 | Return  | description  | optional |
 |---|---|---|   
-|  dict | Dict of OrderedDict with metrics to display in progress bar. All keys must be tensors. | Y |
+|  dict | Dict or OrderedDict - passed to the validation_end step | N |
 
 **Example**
 
 ``` {.python}
-def validation_step(self, data_batch, batch_nb):
-    x, y, z = data_batch
+# CASE 1: A single validation dataset
+def validation_step(self, batch, batch_nb):
+    x, y = batch
     
     # implement your own
     out = self.forward(x)
-    loss = self.loss(out, x)
+    loss = self.loss(out, y)
+    
+    # log 6 example images
+    # or generated text... or whatever
+    sample_imgs = x[:6]
+    grid = torchvision.utils.make_grid(sample_imgs)
+    self.logger.experiment.add_image('example_images', grid, 0) 
     
     # calculate acc
     labels_hat = torch.argmax(out, dim=1)
@@ -171,31 +396,47 @@ def validation_step(self, data_batch, batch_nb):
     
     # return an optional dict
     return output
-```
+```   
+
+If you pass in multiple validation datasets, validation_step will have an additional argument.
+
+```python
+# CASE 2: multiple validation datasets
+def validation_step(self, batch, batch_nb, dataset_idx):
+    # dataset_idx tells you which dataset this is.   
+```   
+
+The ```dataset_idx``` corresponds to the order of datasets returned in ```val_dataloader```.    
 
 --- 
 ### validation_end
 
 ``` {.python}
 def validation_end(self, outputs)
-```
-
-Called at the end of the validation loop with the output of each validation_step.
+```   
+If you didn't define a validation_step, this won't be called. Called at the end of the validation loop with the outputs of validation_step.
 
+The outputs here are strictly for the progress bar. If you don't need to display anything, don't return anything.    
+Any keys present in 'log', 'progress_bar' or the rest of the dictionary are available for callbacks to access.
 **Params**    
 
 | Param  | description  |
 |---|---|
-|  outputs | List of outputs you defined in validation_step |
+|  outputs | List of outputs you defined in validation_step, or if there are multiple dataloaders, a list containing a list of outputs for each dataloader |
 
 **Return**   
 
-| Return  | description  | optional |
-|---|---|---|   
-|  dict | Dict of OrderedDict with metrics to display in progress bar | Y |
+Dictionary or OrderedDict   
+
+| key  | value  | is required |
+|---|---|---|
+|  progress_bar | Dict for progress bar display. Must have only tensors  | N |
+|  log | Dict of metrics to add to logger. Must have only tensors (no images, etc)  | N |
 
 **Example**
 
+With a single dataloader
+
 ``` {.python}
 def validation_end(self, outputs):
     """
@@ -211,68 +452,229 @@ def validation_end(self, outputs):
 
     val_loss_mean /= len(outputs)
     val_acc_mean /= len(outputs)
-    tqdm_dic = {'val_loss': val_loss_mean.item(), 'val_acc': val_acc_mean.item()}
-    return tqdm_dic
+    tqdm_dict = {'val_loss': val_loss_mean.item(), 'val_acc': val_acc_mean.item()}
+       
+    # show val_loss and val_acc in progress bar but only log val_loss
+    results = {
+        'progress_bar': tqdm_dict,
+        'log': {'val_loss': val_loss_mean.item()}
+    }
+    return results
 ```
 
---- 
-### configure_optimizers 
+With multiple dataloaders, `outputs` will be a list of lists. The outer list contains
+one entry per dataloader, while the inner list contains the individual outputs of 
+each validation step for that dataloader.
 
 ``` {.python}
-def configure_optimizers(self)
-```
+def validation_end(self, outputs):
+    """
+    Called at the end of validation to aggregate outputs
+    :param outputs: list of list of individual outputs of each validation step
+    :return:
+    """
+    val_loss_mean = 0
+    val_acc_mean = 0
+    i = 0
+    for dataloader_outputs in outputs:
+        for output in dataloader_outputs:
+            val_loss_mean += output['val_loss']
+            val_acc_mean += output['val_acc']
+            i += 1
 
-Set up as many optimizers as you need. Normally you'd need one. But in the case of GANs or something more esoteric you might have multiple. 
-Lightning will call .backward() and .step() on each one.  If you use 16 bit precision it will also handle that.
-
-
-##### Return
-List - List of optimizers
-
-**Example**
-
-``` {.python}
-# most cases
-def configure_optimizers(self):
-    opt = Adam(lr=0.01)
-    return [opt]
+    val_loss_mean /= i
+    val_acc_mean /= i
+    tqdm_dict = {'val_loss': val_loss_mean.item(), 'val_acc': val_acc_mean.item()}
     
-# gan example
-def configure_optimizers(self):
-    generator_opt = Adam(lr=0.01)
-    disriminator_opt = Adam(lr=0.02)
-    return [generator_opt, disriminator_opt] 
+    # show val_loss and val_acc in progress bar but only log val_loss
+    results = {
+        'progress_bar': tqdm_dict,
+        'log': {'val_loss': val_loss_mean.item()}
+    }
+    return results
 ```
 
---- 
-### get_save_dict 
+### test_step
 
 ``` {.python}
-def get_save_dict(self)
-```
-Called by lightning to checkpoint your model. Lightning saves current epoch, current batch nb, etc...
-All you have to return is what specifically about your lightning model you want to checkpoint.
+# if you have one test dataloader:
+def test_step(self, batch, batch_nb)   
 
-##### Return
-Dictionary - No required keys. Most of the time as described in this example.   
+# if you have multiple test dataloaders:  
+def test_step(self, batch, batch_nb, dataloader_idxdx)
+```
+**OPTIONAL**    
+If you don't need to test you don't need to implement this method. In this step you'd normally generate examples or calculate anything of interest such as accuracy.   
+
+When the validation_step is called, the model has been put in eval mode and PyTorch gradients have been disabled. At the end of validation, model goes back to training mode and gradients are enabled.
+
+The dict you return here will be available in the `test_end` method. 
+
+This function is used when you execute `trainer.test()`.
+
+**Params**   
+
+| Param  | description  |
+|---|---|
+|  batch | The output of your dataloader. A tensor, tuple or list  |
+|  batch_nb | Integer displaying which batch this is  |
+|  dataloader_idx | Integer displaying which dataloader this is (only if multiple test datasets used)  |
+
+**Return**   
+
+| Return  | description  | optional |
+|---|---|---|   
+|  dict | Dict or OrderedDict with metrics to display in progress bar. All keys must be tensors. | Y |
 
 **Example**
 
 ``` {.python}
-def get_save_dict(self):
-    # 99% of use cases this is all you need to return
-    checkpoint = {'state_dict': self.state_dict()}
-    return checkpoint
+# CASE 1: A single test dataset
+def test_step(self, batch, batch_nb):
+    x, y = batch
+    
+    # implement your own
+    out = self.forward(x)
+    loss = self.loss(out, y)
+    
+    # calculate acc
+    labels_hat = torch.argmax(out, dim=1)
+    test_acc = torch.sum(y == labels_hat).item() / (len(y) * 1.0)
+    
+    # all optional...
+    # return whatever you need for the collation function test_end
+    output = OrderedDict({
+        'test_loss': loss_test,
+        'test_acc': torch.tensor(test_acc), # everything must be a tensor
+    })
+    
+    # return an optional dict
+    return output
+```   
+
+If you pass in multiple test datasets, test_step will have an additional argument.
+
+```python
+# CASE 2: multiple test datasets
+def test_step(self, batch, batch_nb, dataset_idx):
+    # dataset_idx tells you which dataset this is.   
+```   
+
+The ```dataset_idx``` corresponds to the order of datasets returned in ```test_dataloader```.    
+
+--- 
+### test_end
+
+``` {.python}
+def test_end(self, outputs)
+```   
+If you didn't define a test_step, this won't be called.       
+
+Called at the end of the test step with the output of each test_step.
+
+The outputs here are strictly for the progress bar. If you don't need to display anything, don't return anything.    
+
+**Params**    
+
+| Param  | description  |
+|---|---|
+|  outputs | List of outputs you defined in test_step, or if there are multiple dataloaders, a list containing a list of outputs for each dataloader |
+
+**Return**   
+
+| Return  | description  | optional |
+|---|---|---|   
+|  dict | Dict of OrderedDict with metrics to display in progress bar | Y |
+
+**Example**
+
+``` {.python}
+def test_end(self, outputs):
+    """
+    Called at the end of test to aggregate outputs
+    :param outputs: list of individual outputs of each test step
+    :return:
+    """
+    test_loss_mean = 0
+    test_acc_mean = 0
+    for output in outputs:
+        test_loss_mean += output['test_loss']
+        test_acc_mean += output['test_acc']
+
+    test_loss_mean /= len(outputs)
+    test_acc_mean /= len(outputs)
+    tqdm_dict = {'test_loss': test_loss_mean.item(), 'test_acc': test_acc_mean.item()}
+    
+    # show test_loss and test_acc in progress bar but only log test_loss
+    results = {
+        'progress_bar': tqdm_dict,
+        'log': {'test_loss': val_loss_mean.item()}
+    }
+    return results
+```
+
+With multiple dataloaders, `outputs` will be a list of lists. The outer list contains
+one entry per dataloader, while the inner list contains the individual outputs of 
+each validation step for that dataloader.
+
+``` {.python}
+def test_end(self, outputs):
+    """
+    Called at the end of test to aggregate outputs
+    :param outputs: list of individual outputs of each test step
+    :return:
+    """
+    test_loss_mean = 0
+    test_acc_mean = 0
+    i = 0
+    for dataloader_outputs in outputs:
+        for output in dataloader_outputs:
+            test_loss_mean += output['test_loss']
+            test_acc_mean += output['test_acc']
+            i += 1
+
+    test_loss_mean /= i 
+    test_acc_mean /= i
+    tqdm_dict = {'test_loss': test_loss_mean.item(), 'test_acc': test_acc_mean.item()}
+    
+    # show test_loss and test_acc in progress bar but only log test_loss
+    results = {
+        'progress_bar': tqdm_dict,
+        'log': {'test_loss': val_loss_mean.item()}
+    }
+    return results
 ```
 
 --- 
-### load_model_specific 
+### on_save_checkpoint 
 
 ``` {.python}
-def load_model_specific(self, checkpoint)
+def on_save_checkpoint(self, checkpoint)
 ```
-Called by lightning to restore your model. This is your chance to restore your model using the keys you added in get_save_dict.
-Lightning will automatically restore current epoch, batch nb, etc. 
+Called by lightning to checkpoint your model. Lightning saves the training state (current epoch, global_step, etc)
+and also saves the model state_dict. If you want to save anything else, use this method to add your own
+key-value pair.
+
+##### Return
+Nothing
+
+**Example**
+
+``` {.python}
+def on_save_checkpoint(self, checkpoint):
+    # 99% of use cases you don't need to implement this method 
+    checkpoint['something_cool_i_want_to_save'] = my_cool_pickable_object
+```
+
+--- 
+### on_load_checkpoint 
+
+``` {.python}
+def on_load_checkpoint(self, checkpoint)
+```
+Called by lightning to restore your model. Lighting auto-restores global step, epoch, etc...
+It also restores the model state_dict.
+If you saved something with **on_save_checkpoint** this is your chance to restore this.
 
 ##### Return
 Nothing  
@@ -280,54 +682,31 @@ Nothing
 **Example**
 
 ``` {.python}
-def load_model_specific(self, checkpoint):
-    # you defined 'state_dict' in get_save_dict()
-    self.load_state_dict(checkpoint['state_dict'])
-```
-
---- 
-### tng_dataloader 
-
-``` {.python}
-@ptl.data_loader
-def tng_dataloader(self)
-```
-Called by lightning during training loop. Make sure to use the @ptl.data_loader decorator, this ensures not calling this function until the data are needed.
-
-##### Return
-Pytorch DataLoader
-
-**Example**
-
-``` {.python}
-@ptl.data_loader
-def tng_dataloader(self):
-    transform = transforms.Compose([transforms.ToTensor(), transforms.Normalize((0.5,), (1.0,))])
-    dataset = MNIST(root='/path/to/mnist/', train=True, transform=transform, download=True)
-    loader = torch.utils.data.DataLoader(
-        dataset=dataset,
-        batch_size=self.hparams.batch_size,
-        shuffle=True
-    )
-    return loader
+def on_load_checkpoint(self, checkpoint):
+    # 99% of the time you don't need to implement this method
+    self.something_cool_i_want_to_save = checkpoint['something_cool_i_want_to_save']
 ```
 
 --- 
 ### val_dataloader 
 
 ``` {.python}
-@ptl.data_loader
-def tng_dataloader(self)
+@pl.data_loader
+def val_dataloader(self)
 ```
-Called by lightning during validation loop. Make sure to use the @ptl.data_loader decorator, this ensures not calling this function until the data are needed.
+**OPTIONAL**    
+If you don't need a validation dataset and a validation_step, you don't need to implement this method.    
+
+Called by lightning during validation loop. Make sure to use the @pl.data_loader decorator, this ensures not calling this function until the data are needed.   
+If you want to change the data during every epoch DON'T use the data_loader decorator.   
 
 ##### Return
-Pytorch DataLoader
+PyTorch DataLoader or list of PyTorch Dataloaders.    
 
 **Example**
 
 ``` {.python}
-@ptl.data_loader
+@pl.data_loader
 def val_dataloader(self):
     transform = transforms.Compose([transforms.ToTensor(), transforms.Normalize((0.5,), (1.0,))])
     dataset = MNIST(root='/path/to/mnist/', train=False, transform=transform, download=True)
@@ -338,24 +717,36 @@ def val_dataloader(self):
     )
     
     return loader
+
+# can also return multiple dataloaders   
+@pl.data_loader
+def val_dataloader(self):
+    return [loader_a, loader_b, ..., loader_n]   
 ```
 
+In the case where you return multiple val_dataloaders, the validation_step will have an arguement ```dataset_idx```
+which matches the order here.    
+
 --- 
 ### test_dataloader 
 
 ``` {.python}
-@ptl.data_loader
+@pl.data_loader
 def test_dataloader(self)
 ```
-Called by lightning during test loop. Make sure to use the @ptl.data_loader decorator, this ensures not calling this function until the data are needed.
+**OPTIONAL**    
+If you don't need a test dataset and a test_step, you don't need to implement this method.    
+
+Called by lightning during test loop. Make sure to use the @pl.data_loader decorator, this ensures not calling this function until the data are needed.
+If you want to change the data during every epoch DON'T use the data_loader decorator.   
 
 ##### Return
-Pytorch DataLoader
+PyTorch DataLoader
 
 **Example**
 
 ``` {.python}
-@ptl.data_loader
+@pl.data_loader
 def test_dataloader(self):
     transform = transforms.Compose([transforms.ToTensor(), transforms.Normalize((0.5,), (1.0,))])
     dataset = MNIST(root='/path/to/mnist/', train=False, transform=transform, download=True)
@@ -368,26 +759,6 @@ def test_dataloader(self):
     return loader
 ```
 
---- 
-### update_tng_log_metrics 
-
-``` {.python}
-def update_tng_log_metrics(self, logs)
-```
-Called by lightning right before it logs metrics for this batch.
-This is a chance to ammend or add to the metrics about to be logged.
-
-##### Return
-Dict 
-
-**Example**
-
-``` {.python}
-def update_tng_log_metrics(self, logs):
-    # modify or add to logs
-    return logs
-```
-
 --- 
 ### add_model_specific_args 
 
@@ -410,7 +781,7 @@ def add_model_specific_args(parent_parser, root_dir):
     parser = HyperOptArgumentParser(strategy=parent_parser.strategy, parents=[parent_parser])
 
     # param overwrites
-    # parser.set_defaults(gradient_clip=5.0)
+    # parser.set_defaults(gradient_clip_val=5.0)
 
     # network params
     parser.opt_list('--drop_prob', default=0.2, options=[0.2, 0.5], type=float, tunable=False)
@@ -427,4 +798,4 @@ def add_model_specific_args(parent_parser, root_dir):
     parser.opt_list('--batch_size', default=256, type=int, options=[32, 64, 128, 256], tunable=False)
     parser.opt_list('--optimizer_name', default='adam', type=str, options=['adam'], tunable=False)
     return parser
-```
+```

docs/LightningModule/methods.md

@@ -10,8 +10,25 @@ model.freeze()
 
 ---    
 ### load_from_metrics
-This is the easiest/fastest way which uses the meta_tags.csv file from test-tube to rebuild the model.
-The meta_tags.csv file can be found in the test-tube experiment save_dir.       
+This is the easiest/fastest way which loads hyperparameters and weights from a checkpoint,
+such as the one saved by the `ModelCheckpoint` callback
+
+```{.python}
+pretrained_model = MyLightningModule.load_from_checkpoint(
+    checkpoint_path='/path/to/pytorch_checkpoint.ckpt'
+)
+    
+# predict
+pretrained_model.eval()
+pretrained_model.freeze()
+y_hat = pretrained_model(x)
+```
+
+---    
+### load_from_metrics
+If you're using test tube, there is an alternate method which uses the meta_tags.csv
+file from test-tube to rebuild the model. The meta_tags.csv file can be found in the
+test-tube experiment save_dir.       
 
 ```{.python}
 pretrained_model = MyLightningModule.load_from_metrics(
@@ -21,7 +38,8 @@ pretrained_model = MyLightningModule.load_from_metrics(
     map_location=None
 )
     
-# predict 
+# predict
+pretrained_model.eval()
 pretrained_model.freeze()
 y_hat = pretrained_model(x)
 ```
@@ -30,7 +48,7 @@ y_hat = pretrained_model(x)
 
 | Param  | description  |
 |---|---|
-|  weights_path | Path to a pytorch checkpoint  |
+|  weights_path | Path to a PyTorch checkpoint  |
 |  tags_csv | Path to meta_tags.csv file generated by the test-tube Experiment  |
 |  on_gpu | if True, puts model on GPU. Make sure to use transforms option if model devices have changed  |
 |  map_location | A dictionary mapping saved weight GPU devices to new GPU devices |

docs/LightningModule/properties.md

@@ -9,12 +9,22 @@ The current epoch
 Current dtype    
 
 ---
-#### experiment    
-An instance of test-tube Experiment which you can use to log anything for tensorboarX.   
+#### logger    
+A reference to the logger you passed into trainer. 
+Passing a logger is optional. If you don't pass one in, Lightning will create one for you automatically.
+This logger saves logs to '''/os.getcwd()/lightning_logs'''
+```python
+Trainer(logger=your_logger)
+```    
+
+Call it from anywhere in your LightningModule to add metrics, images, etc... whatever your logger supports.  
+
+Here is an example using the TestTubeLogger (which is a wrapper on [PyTorch SummaryWriter](https://pytorch.org/docs/stable/tensorboard.html) with versioned folder structure).     
 ```{.python}
-self.experiment.add_embedding(...)   
-self.experiment.log({'val_loss': 0.9})   
-self.experiment.add_scalars(...)   
+# if logger is a tensorboard logger or TestTubeLogger
+self.logger.experiment.add_embedding(...)   
+self.logger.experiment.log({'val_loss': 0.9})   
+self.logger.experiment.add_scalars(...)   
 ```
 
 --- 
@@ -22,7 +32,7 @@ self.experiment.add_scalars(...)
 Total training batches seen across all epochs   
 
 --- 
-#### gradient_clip   
+#### gradient_clip_val   
 The current gradient clip value    
 
 ---
@@ -38,3 +48,17 @@ self.trainer.current_epoch
 ...   
 ```   
 
+## Debugging   
+The LightningModule also offers these tricks to help debug.   
+
+---   
+#### example_input_array    
+In the LightningModule init, you can set a dummy tensor for this property
+to get a print out of sizes coming into and out of every layer.   
+```python
+def __init__(self):
+    # put the dimensions of the first input to your system
+    self.example_input_array = torch.rand(5, 28 * 28)
+```    
+
+

docs/Trainer/Checkpointing.md

@@ -2,21 +2,83 @@ Lightning can automate saving and loading checkpoints.
 
 ---
 ### Model saving
-To enable checkpointing, define the checkpoint callback and give it to the trainer.
+Checkpointing is enabled by default to the current working directory.
+To change the checkpoint path pass in :
+```python
+Trainer(default_save_path='/your/path/to/save/checkpoints')
+```
+
+To modify the behavior of checkpointing pass in your own callback.
 
 ``` {.python}
-from pytorch_lightning.utils.pt_callbacks import ModelCheckpoint
+from pytorch_lightning.callbacks import ModelCheckpoint
 
+# DEFAULTS used by the Trainer
 checkpoint_callback = ModelCheckpoint(
-    filepath='/path/to/store/weights.ckpt',
+    filepath=os.getcwd(),
     save_best_only=True,
     verbose=True,
     monitor='val_loss',
-    mode='min'
+    mode='min',
+    prefix=''
 )
 
 trainer = Trainer(checkpoint_callback=checkpoint_callback)
 ```
 
+---
+### Restoring training session 
+You might want to not only load a model but also continue training it. Use this method to
+restore the trainer state as well. This will continue from the epoch and global step you last left off.  
+However, the dataloaders will start from the first batch again (if you shuffled it shouldn't matter).   
 
+Lightning will restore the session if you pass a logger with the same version and there's a saved checkpoint.   
+``` {.python}
+from pytorch_lightning import Trainer
+from pytorch_lightning.logging import TestTubeLogger
 
+logger = TestTubeLogger(
+    save_dir='./savepath',
+    version=1  # An existing version with a saved checkpoint
+)
+trainer = Trainer(
+    logger=logger,
+    default_save_path='./savepath'
+)
+
+# this fit call loads model weights and trainer state
+# the trainer continues seamlessly from where you left off
+# without having to do anything else.
+trainer.fit(model)
+```
+
+The trainer restores:  
+
+- global_step    
+- current_epoch    
+- All optimizers    
+- All lr_schedulers    
+- Model weights
+
+You can even change the logic of your model as long as the weights and "architecture" of 
+the system isn't different. If you add a layer, for instance, it might not work.   
+
+At a rough level, here's [what happens inside Trainer](https://github.com/williamFalcon/pytorch-lightning/blob/master/pytorch_lightning/root_module/model_saving.py#L63):   
+```python
+
+self.global_step = checkpoint['global_step']
+self.current_epoch = checkpoint['epoch']
+
+# restore the optimizers
+optimizer_states = checkpoint['optimizer_states']
+for optimizer, opt_state in zip(self.optimizers, optimizer_states):
+    optimizer.load_state_dict(opt_state)
+
+# restore the lr schedulers
+lr_schedulers = checkpoint['lr_schedulers']
+for scheduler, lrs_state in zip(self.lr_schedulers, lr_schedulers):
+    scheduler.load_state_dict(lrs_state)
+
+# uses the model you passed into trainer        
+model.load_state_dict(checkpoint['state_dict'])
+```    

docs/Trainer/Distributed training.md

@@ -8,13 +8,30 @@ None of the flags below require changing anything about your lightningModel defi
 Lightning supports two backends. DataParallel and DistributedDataParallel. Both can be used for single-node multi-GPU training.
 For multi-node training you must use DistributedDataParallel.   
 
+##### DataParallel (dp)   
+Splits a batch across multiple GPUs on the same node. Cannot be used for multi-node training.   
+
+##### DistributedDataParallel (ddp)   
+Trains a copy of the model on each GPU and only syncs gradients. If used with DistributedSampler, each GPU trains
+on a subset of the full dataset.  
+
+##### DistributedDataParallel-2 (ddp2)   
+Works like DDP, except each node trains a single copy of the model using ALL GPUs on that node. 
+Very useful when dealing with negative samples, etc...
+
 You can toggle between each mode by setting this flag.
 ``` {.python}
-# DEFAULT uses DataParallel
+# DEFAULT (when using single GPU or no GPUs)
+trainer = Trainer(distributed_backend=None)
+
+# Change to DataParallel (gpus > 1)
 trainer = Trainer(distributed_backend='dp')
 
-# change to distributed data parallel
+# change to distributed data parallel (gpus > 1)
 trainer = Trainer(distributed_backend='ddp')
+
+# change to distributed data parallel (gpus > 1)
+trainer = Trainer(distributed_backend='ddp2')
 ```
 
 If you request multiple nodes, the back-end will auto-switch to ddp.
@@ -23,6 +40,54 @@ have configuration issues depending on your cluster.
 
 For a deeper understanding of what lightning is doing, feel free to read [this guide](https://medium.com/@_willfalcon/9-tips-for-training-lightning-fast-neural-networks-in-pytorch-8e63a502f565).   
 
+---
+#### Distributed and 16-bit precision.    
+Due to an issue with apex and DistributedDataParallel (PyTorch and NVIDIA issue), Lightning does
+not allow 16-bit and DP training. We tried to get this to work, but it's an issue on their end.   
+
+Below are the possible configurations we support.    
+
+| 1 GPU  | 1+ GPUs  | DP  | DDP  | 16-bit  | command |
+|---|---|---|---|---|---|
+| Y  |   |   |   |  | ```Trainer(gpus=1)``` |
+| Y  |   |   |   | Y | ```Trainer(gpus=1, use_amp=True)``` |
+|   | Y | Y |   |   | ```Trainer(gpus=k, distributed_backend='dp')``` |
+|   | Y |  | Y  |  | ```Trainer(gpus=k, distributed_backend='ddp')``` |
+|   | Y |  | Y  | Y | ```Trainer(gpus=k, distributed_backend='ddp', use_amp=True)``` |
+
+You also have the option of specifying which GPUs to use by passing a list:   
+
+```python
+# DEFAULT (int) specifies how many GPUs to use.
+Trainer(gpus=k)  
+
+# Above is equivalent to 
+Trainer(gpus=list(range(k)))
+
+# You specify which GPUs (don't use if running on cluster)  
+Trainer(gpus=[0, 1])  
+
+# can also be a string
+Trainer(gpus='0, 1')
+
+# can also be -1 or '-1', this uses all available GPUs
+# this is equivalent to list(range(torch.cuda.available_devices()))
+Trainer(gpus=-1)
+```
+
+---
+#### CUDA flags   
+CUDA flags make certain GPUs visible to your script. 
+Lightning sets these for you automatically, there's NO NEED to do this yourself.
+```python
+# lightning will set according to what you give the trainer
+# os.environ["CUDA_DEVICE_ORDER"] = "PCI_BUS_ID"
+# os.environ["CUDA_VISIBLE_DEVICES"] = "0"
+```
+
+However, when using a cluster, Lightning will NOT set these flags (and you should not either). 
+SLURM will set these for you.   
+
 ---
 #### 16-bit mixed precision
 16 bit precision can cut your memory footprint by half. If using volta architecture GPUs it can give a dramatic training speed-up as well.    
@@ -30,6 +95,21 @@ First, install apex (if install fails, look [here](https://github.com/NVIDIA/ape
 ```bash
 $ git clone https://github.com/NVIDIA/apex
 $ cd apex
+
+# ------------------------
+# OPTIONAL: on your cluster you might need to load cuda 10 or 9
+# depending on how you installed PyTorch
+
+# see available modules
+module avail
+
+# load correct cuda before install
+module load cuda-10.0
+# ------------------------
+
+# make sure you've loaded a cuda version > 4.0 and < 7.0
+module load gcc-6.1.0
+
 $ pip install -v --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext" ./
 ```
 
@@ -43,12 +123,8 @@ trainer = Trainer(amp_level='O2', use_amp=False)
 #### Single-gpu
 Make sure you're on a GPU machine. 
 ```python
-# set these flags
-os.environ["CUDA_DEVICE_ORDER"] = "PCI_BUS_ID"
-os.environ["CUDA_VISIBLE_DEVICES"] = "0"
-
 # DEFAULT
-trainer = Trainer(gpus=[0])
+trainer = Trainer(gpus=1)
 ```
 
 ---
@@ -56,57 +132,63 @@ trainer = Trainer(gpus=[0])
 Make sure you're on a GPU machine. You can set as many GPUs as you want.
 In this setting, the model will run on all 8 GPUs at once using DataParallel under the hood.
 ```python
-# set these flags
-# lightning sets these flags for you automatically
-# no need to set yourself
-# os.environ["CUDA_DEVICE_ORDER"] = "PCI_BUS_ID"
-# os.environ["CUDA_VISIBLE_DEVICES"] = "0,1,2,3,4,5,6,7"
-
-
-# to use DataParallel (default)
-trainer = Trainer(gpus=[0,1,2,3,4,5,6,7], distributed_backend='dp')
+# to use DataParallel
+trainer = Trainer(gpus=8, distributed_backend='dp')
 
 # RECOMMENDED use DistributedDataParallel
-trainer = Trainer(gpus=[0,1,2,3,4,5,6,7], distributed_backend='ddp')
+trainer = Trainer(gpus=8, distributed_backend='ddp')
 ```
 
 ---
 #### Multi-node
-Multi-node training is easily done by specifying these flags.
+Multi-node training is easily done by specifying these flags. 
 ```python
 # train on 12*8 GPUs
-trainer = Trainer(gpus=[0,1,2,3,4,5,6,7], nb_gpu_nodes=12)
+trainer = Trainer(gpus=8, nb_gpu_nodes=12, distributed_backend='ddp')
 ```
 
-In addition, make sure to set up your SLURM job correctly via the [SlurmClusterObject](https://williamfalcon.github.io/test-tube/hpc/SlurmCluster/). In particular, specify the number of tasks per node correctly.
+You must configure your job submission script correctly for the trainer to work. Here is an example
+script for the above trainer configuration.   
 
-```python
-cluster = SlurmCluster(
-    hyperparam_optimizer=test_tube.HyperOptArgumentParser(),
-    log_path='/some/path/to/save',
-)
+```sh
+#!/bin/bash -l
 
-# OPTIONAL FLAGS WHICH MAY BE CLUSTER DEPENDENT
-# which interface your nodes use for communication
-cluster.add_command('export NCCL_SOCKET_IFNAME=^docker0,lo')
+# SLURM SUBMIT SCRIPT
+#SBATCH --nodes=12
+#SBATCH --gres=gpu:8
+#SBATCH --ntasks-per-node=8
+#SBATCH --mem=0
+#SBATCH --time=0-02:00:00
 
-# see output of the NCCL connection process
-# NCCL is how the nodes talk to each other
-cluster.add_command('export NCCL_DEBUG=INFO')
+# activate conda env
+conda activate my_env
 
-# setting a master port here is a good idea.
-cluster.add_command(f'export MASTER_PORT={PORT}')
+# -------------------------
+# OPTIONAL
+# -------------------------
+# debugging flags (optional)
+# export NCCL_DEBUG=INFO
+# export PYTHONFAULTHANDLER=1
 
-# good to load the latest NCCL version
-cluster.load_modules(['NCCL/2.4.7-1-cuda.10.0'])
+# PyTorch comes with prebuilt NCCL support... but if you have issues with it
+# you might need to load the latest version from your  modules
+# module load NCCL/2.4.7-1-cuda.10.0
 
-# configure cluster
-cluster.per_experiment_nb_nodes = 12 
-cluster.per_experiment_nb_gpus = 8
+# on your cluster you might need these:
+# set the network interface
+# export NCCL_SOCKET_IFNAME=^docker0,lo
+# -------------------------
 
-cluster.add_slurm_cmd(cmd='ntasks-per-node', value=8, comment='1 task per gpu')
+# random port between 12k and 20k
+export MASTER_PORT=$((12000 + RANDOM % 20000))
+
+# run script from above
+python my_main_file.py
 ```
 
+**NOTE:** When running in DDP mode, any errors in your code will show up as an NCCL issue.
+Set the ```NCCL_DEBUG=INFO``` flag to see the ACTUAL error.
+
 Finally, make sure to add a distributed sampler to your dataset. The distributed sampler copies a 
 portion of your dataset onto each GPU. (World_size = gpus_per_node * nb_nodes).   
 
@@ -121,6 +203,58 @@ dist_sampler = torch.utils.data.distributed.DistributedSampler(dataset)
 dataloader = Dataloader(dataset, sampler=dist_sampler)
 ```
 
+#### Auto-slurm-job-submission
+Instead of manually building SLURM scripts, you can use the [SlurmCluster object](https://williamfalcon.github.io/test-tube/hpc/SlurmCluster/) to
+do this for you. The SlurmCluster can also run a grid search if you pass in a [HyperOptArgumentParser](https://williamfalcon.github.io/test-tube/hyperparameter_optimization/HyperOptArgumentParser/).
+
+Here is an example where you run a grid search of 9 combinations of hyperparams.
+[The full examples are here](https://github.com/williamFalcon/pytorch-lightning/tree/master/pl_examples/new_project_templates/multi_node_examples).
+```python
+# grid search 3 values of learning rate and 3 values of number of layers for your net
+# this generates 9 experiments (lr=1e-3, layers=16), (lr=1e-3, layers=32), (lr=1e-3, layers=64), ... (lr=1e-1, layers=64)
+parser = HyperOptArgumentParser(strategy='grid_search', add_help=False)
+parser.opt_list('--learning_rate', default=0.001, type=float, options=[1e-3, 1e-2, 1e-1], tunable=True)
+parser.opt_list('--layers', default=1, type=float, options=[16, 32, 64], tunable=True)
+hyperparams = parser.parse_args()
+
+# Slurm cluster submits 9 jobs, each with a set of hyperparams
+cluster = SlurmCluster(
+    hyperparam_optimizer=hyperparams,
+    log_path='/some/path/to/save',
+)
+
+# OPTIONAL FLAGS WHICH MAY BE CLUSTER DEPENDENT
+# which interface your nodes use for communication
+cluster.add_command('export NCCL_SOCKET_IFNAME=^docker0,lo')
+
+# see output of the NCCL connection process
+# NCCL is how the nodes talk to each other
+cluster.add_command('export NCCL_DEBUG=INFO')
+
+# setting a master port here is a good idea.
+cluster.add_command('export MASTER_PORT=%r' % PORT)
+
+# ************** DON'T FORGET THIS ***************
+# MUST load the latest NCCL version
+cluster.load_modules(['NCCL/2.4.7-1-cuda.10.0'])
+
+# configure cluster
+cluster.per_experiment_nb_nodes = 12 
+cluster.per_experiment_nb_gpus = 8
+
+cluster.add_slurm_cmd(cmd='ntasks-per-node', value=8, comment='1 task per gpu')  
+
+# submit a script with 9 combinations of hyper params
+# (lr=1e-3, layers=16), (lr=1e-3, layers=32), (lr=1e-3, layers=64), ... (lr=1e-1, layers=64)
+cluster.optimize_parallel_cluster_gpu(
+    main,
+    nb_trials=9, # how many permutations of the grid search to run
+    job_name='name_for_squeue'
+)
+```
+
+The other option is that you generate scripts on your own via a bash command or use another library...
+
 ---
 #### Self-balancing architecture
 Here lightning distributes parts of your module across available GPUs to optimize for speed and memory.   

docs/Trainer/Logging.md

@@ -1,11 +1,164 @@
-Lighting offers a few options for logging information about model, gpu usage, etc (via test-tube). It also offers printing options for training monitoring.
+Lighting offers options for logging information about model, gpu usage, etc, via several different logging frameworks. It also offers printing options for training monitoring.
+
+---   
+### default_save_path   
+Lightning sets a default TestTubeLogger and CheckpointCallback for you which log to
+```os.getcwd()``` by default. To modify the logging path you can set:
+```python
+Trainer(default_save_path='/your/path/to/save/checkpoints')
+```
+ 
+If you need more custom behavior (different paths for both, different metrics, etc...)
+from the logger and the checkpointCallback, pass in your own instances as explained below.
 
 
 ---
+### Setting up logging
+
+The trainer inits a default logger for you (TestTubeLogger). All logs will
+go to the current working directory under a folder named ```os.getcwd()/lightning_logs``. 
+
+If you want to modify the default logging behavior even more, pass in a logger
+(which should inherit from `LightningBaseLogger`).   
+
+```{.python}
+my_logger = MyLightningLogger(...)
+trainer = Trainer(logger=my_logger)
+```
+
+The path in this logger will overwrite default_save_path.
+
+Lightning supports several common experiment tracking frameworks out of the box
+
+---
+#### Test tube
+
+Log using [test tube](https://williamfalcon.github.io/test-tube/). Test tube logger is
+a strict subclass of [PyTorch SummaryWriter](https://pytorch.org/docs/stable/tensorboard.html), refer to their
+documentation for all supported operations. The TestTubeLogger adds a nicer folder structure
+to manage experiments and snapshots all hyperparameters you pass to a LightningModule.
+
+```{.python}
+from pytorch_lightning.logging import TestTubeLogger
+tt_logger = TestTubeLogger(
+    save_dir=".",
+    name="default",
+    debug=False,
+    create_git_tag=False
+)
+trainer = Trainer(logger=tt_logger)
+```
+
+Use the logger anywhere in you LightningModule as follows:
+```python
+def train_step(...):
+    # example
+    self.logger.experiment.whatever_method_summary_writer_supports(...)
+    
+def any_lightning_module_function_or_hook(...):
+    self.logger.experiment.add_histogram(...)
+```
+
+---
+#### MLFlow
+
+Log using [mlflow](https://mlflow.org)
+
+```{.python}
+from pytorch_lightning.logging import MLFlowLogger
+mlf_logger = MLFlowLogger(
+    experiment_name="default",
+    tracking_uri="file:/."
+)
+trainer = Trainer(logger=mlf_logger)
+```
+Use the logger anywhere in you LightningModule as follows:
+```python
+def train_step(...):
+    # example
+    self.logger.experiment.whatever_ml_flow_supports(...)
+    
+def any_lightning_module_function_or_hook(...):
+    self.logger.experiment.whatever_ml_flow_supports(...)
+```
+
+---
+#### Comet.ml
+
+Log using [comet](https://www.comet.ml)
+
+```{.python}
+from pytorch_lightning.logging import CometLogger
+# arguments made to CometLogger are passed on to the comet_ml.Experiment class
+comet_logger = CometLogger(
+    api_key=os.environ["COMET_KEY"],
+    workspace=os.environ["COMET_KEY"],
+)
+trainer = Trainer(logger=comet_logger)
+```
+Use the logger anywhere in you LightningModule as follows:
+```python
+def train_step(...):
+    # example
+    self.logger.experiment.whatever_comet_ml_supports(...)
+
+def any_lightning_module_function_or_hook(...):
+    self.logger.experiment.whatever_comet_ml_supports(...)
+```
+
+---
+#### Custom logger
+
+You can implement your own logger by writing a class that inherits from
+`LightningLoggerBase`. Use the `rank_zero_only` decorator to make sure that
+only the first process in DDP training logs data.
+
+```{.python}
+from pytorch_lightning.logging import LightningLoggerBase, rank_zero_only
+
+class MyLogger(LightningLoggerBase):
+
+    @rank_zero_only
+    def log_hyperparams(self, params):
+        # params is an argparse.Namespace
+        # your code to record hyperparameters goes here
+        pass
+    
+    @rank_zero_only
+    def log_metrics(self, metrics, step_num):
+        # metrics is a dictionary of metric names and values
+        # your code to record metrics goes here
+        pass
+    
+    def save(self):
+        # Optional. Any code necessary to save logger data goes here
+        pass
+    
+    @rank_zero_only
+    def finalize(self, status):
+        # Optional. Any code that needs to be run after training
+        # finishes goes here
+```
+
+If you write a logger than may be useful to others, please send
+a pull request to add it to Lighting!
+
+---
+#### Using loggers
+You can call the logger anywhere from your LightningModule by doing:
+```python
+def train_step(...):
+    # example
+    self.logger.experiment.whatever_method_summary_writer_supports(...)
+    
+def any_lightning_module_function_or_hook(...):
+    self.logger.experiment.add_histogram(...)
+```
+
 #### Display metrics in progress bar 
 ``` {.python}
 # DEFAULT
-trainer = Trainer(progress_bar=True)
+trainer = Trainer(show_progress_bar=True)
 ```
 
 ---
@@ -13,7 +166,21 @@ trainer = Trainer(progress_bar=True)
 Every k batches lightning will make an entry in the metrics log
 ``` {.python}
 # DEFAULT (ie: save a .csv log file every 10 batches)
-trainer = Trainer(add_log_row_interval=10)
+trainer = Trainer(row_log_interval=10)
+```   
+
+---
+#### Log GPU memory
+Logs GPU memory when metrics are logged.   
+``` {.python}
+# DEFAULT
+trainer = Trainer(log_gpu_memory=None)
+
+# log only the min/max utilization
+trainer = Trainer(log_gpu_memory='min_max')
+
+# log all the GPU memory (if on DDP, logs only that node)
+trainer = Trainer(log_gpu_memory='all')
 ```
 
 ---
@@ -30,27 +197,23 @@ trainer = Trainer(process_position=1)
 
 ---
 #### Save a snapshot of all hyperparameters 
-Whenever you call .save() on the test-tube experiment it logs all the hyperparameters in current use.
-Give lightning a test-tube Experiment object to automate this for you.
+Automatically log hyperparameters stored in the `hparams` attribute as an `argparse.Namespace` 
 ``` {.python}
-from test-tube import Experiment
 
-exp = Experiment(...)
-Trainer(experiment=exp)
+class MyModel(pl.Lightning):
+    def __init__(self, hparams):
+        self.hparams = hparams
+
+    ...
+
+args = parser.parse_args()
+model = MyModel(args)
+
+logger = TestTubeLogger(...)
+t = Trainer(logger=logger)
+trainer.fit(model)
 ```
 
----
-#### Snapshot code for a training run
-Whenever you call .save() on the test-tube experiment it snapshows all code and pushes to a git tag.
-Give lightning a test-tube Experiment object to automate this for you.
-``` {.python}
-from test-tube import Experiment
-
-exp = Experiment(create_git_tag=True)
-Trainer(experiment=exp)
-```
-
-
 ---
 #### Write logs file to csv every k batches 
 Every k batches, lightning will write the new logs to disk

docs/Trainer/SLURM Managed Cluster.md

@@ -1,8 +1,10 @@
 Lightning supports model training on a cluster managed by SLURM in the following cases:    
 
-1. Training on single or multi-cpus only.
-2. Training on single or multi-gpus on the same node.
-3. Coming SOON: Training across multiple nodes.
+1. Training on a single cpu or single GPU.
+2. Train on multiple GPUs on the same node using DataParallel or DistributedDataParallel
+3. Training across multiple GPUs on multiple different nodes via DistributedDataParallel.
+
+**Note: A node means a machine with multiple GPUs**
 
 ---
 #### Running grid search on a cluster
@@ -23,6 +25,9 @@ parser.opt_list('--nb_layers', default=2, type=int, tunable=True, options=[2, 4,
 hparams = parser.parse_args()    
 ```    
     
+**NOTE** You must set ```Tunable=True``` for that argument to be considered in the permutation set. Otherwise
+test-tube will use the default value. This flag is useful when you don't want to search over an argument and
+want to use the default instead.   
      
 (2). Define the cluster options in the [SlurmCluster object](https://williamfalcon.github.io/test-tube/hpc/SlurmCluster/) (over 5 nodes and 8 gpus)    
 
@@ -55,8 +60,8 @@ cluster.memory_mb_per_node = 10000
 cluster.job_time = '10:00'
 ```
 
-(3). Give trainer the cluster_manager in your main function:    
-
+(3). Make a main function with your model and trainer. Each job will call this function with a particular
+hparams configuration.    
 ```{.python}
 from pytorch_lightning import Trainer
 
@@ -66,12 +71,12 @@ def train_fx(trial_hparams, cluster_manager, _):
     my_model = MyLightningModel()
     
     # give the trainer the cluster object
-    trainer = Trainer(cluster=cluster_manager)
+    trainer = Trainer()
     trainer.fit(my_model)
 
 ```
 
-(4). Start the grid search     
+(3). Start the grid/random search     
 ```{.python}
 # run the models on the cluster
 cluster.optimize_parallel_cluster_gpu(
@@ -81,24 +86,27 @@ cluster.optimize_parallel_cluster_gpu(
     job_display_name='my_exp')
 ```
 
-That's it! The SlurmCluster object will automatically checkpoint the lightning model and resubmit if it runs into the walltime!
-
+**NOTE** nb_trials specifies how many of the possible permutations to use. If using ```grid_search``` it will use
+the depth first ordering. If using ```random_search``` it will use the first k shuffled options. FYI, random search
+has been shown to be just as good as any Bayesian optimization method when using a reasonable number of samples (60),
+[see this paper for more information](http://www.jmlr.org/papers/volume13/bergstra12a/bergstra12a.pdf).
 
 ---
 #### Walltime auto-resubmit
-Lightning automatically resubmits jobs when they reach the walltime. You get this behavior for free if you give lightning
-a slurm cluster object.
+Lightning automatically resubmits jobs when they reach the walltime. Make sure to set the SIGUSR1 signal in 
+your SLURM script.   
 
-```{.python}
-def my_main_fx(hparams, slurm_manager, _):
-    trainer = Trainer(cluster=slurm_manager)
+```bash
+# 90 seconds before training ends
+#SBATCH --signal=SIGUSR1@90
 ``` 
 
-(See the grid search example above for cluster configuration).
-With this feature lightning will:    
+When lightning receives the SIGUSR1 signal it will:
+1. save a checkpoint with 'hpc_ckpt' in the name.
+2. resubmit the job using the SLURM_JOB_ID  
+
+When the script starts again, Lightning will:
+1. search for a 'hpc_ckpt' checkpoint. 
+2. restore the model, optimizers, schedulers, epoch, etc...   
 
-1. automatically checkpoint the model
-2. checkpoint the trainer session
-3. resubmit a continuation job.
-4. load the checkpoint and trainer session in the new model
 

docs/Trainer/Testing loop.md

@@ -0,0 +1,31 @@
+To ensure you don't accidentally use test data to guide training decisions Lightning makes running the test set deliberate.   
+
+---
+#### test
+You have two options to run the test set. 
+First case is where you test right after a full training routine.
+``` {.python}
+# run full training
+trainer.fit(model)
+
+# run test set
+trainer.test()
+```   
+
+Second case is where you load a model and run the test set   
+```{.python}
+model = MyLightningModule.load_from_metrics(
+    weights_path='/path/to/pytorch_checkpoint.ckpt',
+    tags_csv='/path/to/test_tube/experiment/version/meta_tags.csv',
+    on_gpu=True,
+    map_location=None
+)
+
+# init trainer with whatever options
+trainer = Trainer(...)
+    
+# test (pass in the model)
+trainer.test(model)
+```
+In this second case, the options you pass to trainer will be used when running the test set (ie: 16-bit, dp, ddp, etc...)  
+ 

docs/Trainer/Training Loop.md

@@ -1,27 +1,16 @@
-The lightning training loop handles everything except the actual computations of your model. To decide what will happen in your training loop, define the [training_step function](../../Pytorch-lightning/LightningModule/#training_step).
+The lightning training loop handles everything except the actual computations of your model. To decide what will happen in your training loop, define the [training_step function](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/#training_step).
 
 Below are all the things lightning automates for you in the training loop.
 
 ---
-#### Accumulated gradients  
-Accumulated gradients runs K small batches of size N before doing a backwards pass. The effect is a large effective batch size of size KxN. 
+#### Accumulated gradients
+Accumulated gradients runs K small batches of size N before doing a backwards pass. The effect is a large effective batch size of size KxN.
 
 ``` {.python}
 # DEFAULT (ie: no accumulated grads)
 trainer = Trainer(accumulate_grad_batches=1)
 ```
 
----
-#### Anneal Learning rate
-Cut the learning rate by 10 at every epoch listed in this list.
-``` {.python}
-# DEFAULT (don't anneal)
-trainer = Trainer(lr_scheduler_milestones=None)
-
-# cut LR by 10 at 100, 200, and 300 epochs 
-trainer = Trainer(lr_scheduler_milestones='100, 200, 300')
-```
-
 ---
 #### Force training for min or max epochs
 It can be useful to force training for a minimum number of epochs or limit to a max number
@@ -31,22 +20,51 @@ trainer = Trainer(min_nb_epochs=1, max_nb_epochs=1000)
 ```
 
 ---
-#### Force disable early stop 
-Use this to turn off early stopping and run training to the [max_epoch](#force-training-for-min-or-max-epochs)
+#### Early stopping
+The trainer already sets up default early stopping for you.
+To modify this behavior, pass in your own EarlyStopping callback.
 ``` {.python}
-# DEFAULT
-trainer = Trainer(enable_early_stop=True)
+from pytorch_lightning.callbacks import EarlyStopping
+
+# DEFAULTS used by Trainer
+early_stop_callback = EarlyStopping(
+    monitor='val_loss',
+    min_delta=0.00,
+    patience=3,
+    verbose=False,
+    mode='min'
+)
+
+# without passing anything in, uses the default callback above
+trainer = Trainer()
+
+# pass in your own to override the default callback
+trainer = Trainer(early_stop_callback=early_stop_callback)
+
+# pass in None to disable it
+trainer = Trainer(early_stop_callback=None)
 ```
 
 ---
-#### Gradient Clipping 
-Use this to turn off early stopping and run training to the [max_epoch](#force-training-for-min-or-max-epochs)
+#### Force disable early stop
+To disable early stopping pass None to the early_stop_callback
 ``` {.python}
-# DEFAULT (ie: don't clip)
-trainer = Trainer(gradient_clip=0)
+# DEFAULT
+trainer = Trainer(early_stop_callback=None)
 ```
 
+---
+#### Gradient Clipping
+Gradient clipping may be enabled to avoid exploding gradients.
+Specifically, this will [clip the gradient norm computed over all model parameters *together*](https://pytorch.org/docs/stable/nn.html#torch.nn.utils.clip_grad_norm_).
 
+``` {.python}
+# DEFAULT (ie: don't clip)
+trainer = Trainer(gradient_clip_val=0)
+
+# clip gradients with norm above 0.5
+trainer = Trainer(gradient_clip_val=0.5)
+```
 
 ---
 #### Inspect gradient norms
@@ -62,7 +80,10 @@ trainer = Trainer(track_grad_norm=2)
 
 ---
 #### Set how much of the training set to check
-If you don't want to check 100% of the training set (for debugging or if it's huge), set this flag
+If you don't want to check 100% of the training set (for debugging or if it's huge), set this flag.
+
+train_percent_check will be overwritten by overfit_pct if `overfit_pct > 0`
+
 ``` {.python}
 # DEFAULT
 trainer = Trainer(train_percent_check=1.0)
@@ -70,3 +91,36 @@ trainer = Trainer(train_percent_check=1.0)
 # check 10% only
 trainer = Trainer(train_percent_check=0.1)
 ```
+
+---
+#### Packed sequences as inputs
+When using PackedSequence, do 2 things:
+1. return either a padded tensor in dataset or a list of variable length tensors in the dataloader collate_fn (example above shows the list implementation).    
+2. Pack the sequence in forward or training and validation steps depending on use case.
+
+``` {.python}
+# For use in dataloader
+def collate_fn(batch):
+    x = [item[0] for item in batch]
+    y = [item[1] for item in batch]
+    return x, y
+
+# In module
+def training_step(self, batch, batch_nb):
+    x = rnn.pack_sequence(batch[0], enforce_sorted=False)
+    y = rnn.pack_sequence(batch[1], enforce_sorted=False)
+```
+
+---
+#### Truncated Back Propagation Through Time
+There are times when multiple backwards passes are needed for each batch. For example, it may save memory to use Truncated Back Propagation Through Time when training RNNs.
+
+When this flag is enabled each batch is split into sequences of size truncated_bptt_steps and passed to training_step(...) separately. A default splitting function is provided, however, you can override it for more flexibility. See [tbptt_split_batch](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks#tbptt_split_batch).
+
+``` {.python}
+# DEFAULT (single backwards pass per batch)
+trainer = Trainer(truncated_bptt_steps=None)
+
+# (split batch into sequences of size 2)
+trainer = Trainer(truncated_bptt_steps=2)
+```

docs/Trainer/Validation loop.md

@@ -1,12 +1,10 @@
-The lightning validation loop handles everything except the actual computations of your model. To decide what will happen in your validation loop, define the [validation_step function](../../Pytorch-lightning/LightningModule/#validation_step).
+The lightning validation loop handles everything except the actual computations of your model. To decide what will happen in your validation loop, define the [validation_step function](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/#validation_step).
 Below are all the things lightning automates for you in the validation loop.
 
 **Note**   
 Lightning will run 5 steps of validation in the beginning of training as a sanity check so you don't have to wait until a full epoch to catch possible validation issues.
 
 
-
-
 ---
 #### Check validation every n epochs
 If you have a small dataset you might want to check validation every n epochs
@@ -18,6 +16,9 @@ trainer = Trainer(check_val_every_n_epoch=1)
 ---
 #### Set how much of the validation set to check 
 If you don't want to check 100% of the validation set (for debugging or if it's huge), set this flag
+
+val_percent_check will be overwritten by overfit_pct if `overfit_pct > 0`
+
 ``` {.python}
 # DEFAULT
 trainer = Trainer(val_percent_check=1.0)
@@ -29,6 +30,9 @@ trainer = Trainer(val_percent_check=0.1)
 ---
 #### Set how much of the test set to check 
 If you don't want to check 100% of the test set (for debugging or if it's huge), set this flag
+
+test_percent_check will be overwritten by overfit_pct if `overfit_pct > 0`
+
 ``` {.python}
 # DEFAULT
 trainer = Trainer(test_percent_check=1.0)
@@ -39,13 +43,20 @@ trainer = Trainer(test_percent_check=0.1)
 
 ---
 ####  Set validation check frequency within 1 training epoch
-For large datasets it's often desirable to check validation multiple times within a training loop
+For large datasets it's often desirable to check validation multiple times within a training loop.
+Pass in a float to check that often within 1 training epoch.
+Pass in an int k to check every k training batches. Must use an int if using 
+an IterableDataset.
+ 
 ``` {.python}
 # DEFAULT
 trainer = Trainer(val_check_interval=0.95)
 
 # check every .25 of an epoch 
 trainer = Trainer(val_check_interval=0.25)
+
+# check every 100 train batches (ie: for IterableDatasets or fixed frequency)
+trainer = Trainer(val_check_interval=100)
 ```
 
 ---
@@ -54,4 +65,6 @@ Lightning runs a few steps of validation in the beginning of training. This avoi
 ``` {.python}
 # DEFAULT
 trainer = Trainer(nb_sanity_val_steps=5)
-```
+```
+
+You can use `Trainer(nb_sanity_val_steps=0)` to skip the sanity check.

docs/Trainer/debugging.md

@@ -23,6 +23,9 @@ trainer = Trainer(track_grad_norm=2)
 ---
 #### Make model overfit on subset of data
 A useful debugging trick is to make your model overfit a tiny fraction of the data.
+
+setting `overfit_pct > 0` will overwrite train_percent_check, val_percent_check, test_percent_check
+
 ``` {.python}
 # DEFAULT don't overfit (ie: normal training)
 trainer = Trainer(overfit_pct=0.0)
@@ -35,6 +38,14 @@ trainer = Trainer(overfit_pct=0.01)
 #### Print the parameter count by layer
 By default lightning prints a list of parameters *and submodules* when it starts training.
 
+``` {.python}
+# DEFAULT print a full list of all submodules and their parameters.
+trainer = Trainer(weights_summary='full')
+
+# only print the top-level modules (i.e. the children of LightningModule).
+trainer = Trainer(weights_summary='top')
+```
+
 ---
 #### Print which gradients are nan 
 This option prints a list of tensors with nan gradients.

docs/Trainer/hooks.md

@@ -0,0 +1,266 @@
+# Hooks
+[[Github Code](https://github.com/williamFalcon/pytorch-lightning/blob/master/pytorch_lightning/root_module/hooks.py)]   
+
+There are cases when you might want to do something different at different parts of the training/validation loop.
+To enable a hook, simply override the method in your LightningModule and the trainer will call it at the correct time.
+
+**Contributing** If there's a hook you'd like to add, simply:    
+1. Fork PyTorchLightning.    
+2. Add the hook [here](https://github.com/williamFalcon/pytorch-lightning/blob/master/pytorch_lightning/root_module/hooks.py).       
+3. Add the correct place in the [Trainer](https://github.com/williamFalcon/pytorch-lightning/blob/master/pytorch_lightning/models/trainer.py) where it should be called.    
+
+---
+#### on_epoch_start
+Called in the training loop at the very beginning of the epoch.   
+```python
+def on_epoch_start(self):
+    # do something when the epoch starts
+```
+
+---
+#### on_epoch_end
+Called in the training loop at the very end of the epoch.   
+```python
+def on_epoch_end(self):
+    # do something when the epoch ends 
+```
+
+---
+#### on_batch_start
+Called in the training loop before anything happens for that batch.   
+```python
+def on_batch_start(self):
+    # do something when the batch starts
+```
+
+---
+#### on_batch_end
+Called in the training loop after the batch.   
+```python
+def on_batch_end(self):
+    # do something when the batch ends 
+```
+
+---
+#### on_pre_performance_check
+Called at the very beginning of the validation loop.   
+```python
+def on_pre_performance_check(self):
+    # do something before validation starts 
+```
+
+---
+#### on_post_performance_check
+Called at the very end of the validation loop.   
+```python
+def on_post_performance_check(self):
+    # do something before validation end
+```
+
+---
+#### optimizer_step 
+Calls .step() and .zero_grad for each optimizer.  
+You can override this method to adjust how you do the optimizer step for each optimizer
+
+Called once per optimizer
+```python
+# DEFAULT
+def optimizer_step(self, current_epoch, batch_nb, optimizer, optimizer_i, second_order_closure=None):
+    optimizer.step()   
+    optimizer.zero_grad()   
+    
+# Alternating schedule for optimizer steps (ie: GANs)    
+def optimizer_step(self, current_epoch, batch_nb, optimizer, optimizer_i, second_order_closure=None):
+    # update generator opt every 2 steps
+    if optimizer_i == 0:
+        if batch_nb % 2 == 0 :
+            optimizer.step()
+            optimizer.zero_grad()
+   
+    # update discriminator opt every 4 steps
+    if optimizer_i == 1:
+        if batch_nb % 4 == 0 :
+            optimizer.step()
+            optimizer.zero_grad()    
+    
+    # ...
+    # add as many optimizers as you want 
+```
+
+This step allows you to do a lot of non-standard training tricks such as learning-rate warm-up:   
+
+```python
+# learning rate warm-up
+def optimizer_step(self, current_epoch, batch_nb, optimizer, optimizer_i, second_order_closure=None):
+    # warm up lr
+    if self.trainer.global_step < 500:
+        lr_scale = min(1., float(self.trainer.global_step + 1) / 500.)
+        for pg in optimizer.param_groups:
+            pg['lr'] = lr_scale * self.hparams.learning_rate
+    
+    # update params
+    optimizer.step()
+    optimizer.zero_grad() 
+```
+
+
+---
+#### on_before_zero_grad
+Called in the training loop after taking an optimizer step and before zeroing grads.
+Good place to inspect weight information with weights updated.
+
+Called once per optimizer
+```python
+def on_before_zero_grad(self, optimizer):
+    # do something with the optimizer or inspect it. 
+```
+
+---
+#### backward
+Called to perform backward step.
+Feel free to override as needed.
+
+The loss passed in has already been scaled for accumulated gradients if requested.
+```python
+def backward(self, use_amp, loss, optimizer):
+    """
+    Override backward with your own implementation if you need to
+    :param use_amp: Whether amp was requested or not
+    :param loss: Loss is already scaled by accumulated grads
+    :param optimizer: Current optimizer being used
+    :return:
+    """
+    if use_amp:
+        with amp.scale_loss(loss, optimizer) as scaled_loss:
+            scaled_loss.backward()
+    else:
+        loss.backward()
+```
+
+---
+#### on_after_backward
+Called in the training loop after model.backward()
+This is the ideal place to inspect or log gradient information 
+```python
+def on_after_backward(self):
+    # example to inspect gradient information in tensorboard
+    if self.trainer.global_step % 25 == 0:  # don't make the tf file huge
+        params = self.state_dict()
+        for k, v in params.items():
+            grads = v
+            name = k
+            self.logger.experiment.add_histogram(tag=name, values=grads, global_step=self.trainer.global_step)
+```
+
+---
+#### tbptt_split_batch
+Called in the training loop after on_batch_start if `truncated_bptt_steps > 0`. Each returned batch split is passed separately to training_step(...).
+
+```python
+def tbptt_split_batch(self, batch, split_size):
+  splits = []
+  for t in range(0, time_dims[0], split_size):
+      batch_split = []
+      for i, x in enumerate(batch):
+          if isinstance(x, torch.Tensor):
+              split_x = x[:, t:t + split_size]
+          elif isinstance(x, collections.Sequence):
+              split_x = [None] * len(x)
+              for batch_idx in range(len(x)):
+                  split_x[batch_idx] = x[batch_idx][t:t + split_size]
+
+          batch_split.append(split_x)
+
+      splits.append(batch_split)
+
+  return splits
+```
+
+---
+#### configure_apex
+Overwrite to define your own Apex implementation init.
+
+```python
+def configure_apex(self, amp, model, optimizers, amp_level):
+    """
+    Override to init AMP your own way
+    Must return a model and list of optimizers
+    :param amp:
+    :param model:
+    :param optimizers:
+    :param amp_level:
+    :return: Apex wrapped model and optimizers
+    """
+    model, optimizers = amp.initialize(
+        model, optimizers, opt_level=amp_level,
+    )
+
+    return model, optimizers
+```
+
+---
+#### configure_ddp 
+Overwrite to define your own DDP implementation init.
+The only requirement is that:
+1. On a validation batch the call goes to model.validation_step.   
+2. On a training batch the call goes to model.training_step.   
+3. On a testing batch, the call goes to model.test_step
+
+```python
+def configure_ddp(self, model, device_ids):
+    """
+    Override to init DDP in a different way or use your own wrapper.
+    Must return model.
+    :param model:
+    :param device_ids:
+    :return: DDP wrapped model
+    """
+    # Lightning DDP simply routes to test_step, val_step, etc...
+    model = LightningDistributedDataParallel(
+        model,
+        device_ids=device_ids,
+        find_unused_parameters=True
+    )
+    return model
+```
+
+---   
+#### init_ddp_connection   
+Override to init DDP in your own way.   
+
+```python
+def init_ddp_connection(self):
+    """
+    Connect all procs in the world using the env:// init
+    Use the first node as the root address
+    """
+
+    # use slurm job id for the port number
+    # guarantees unique ports across jobs from same grid search
+    try:
+        # use the last 4 numbers in the job id as the id
+        default_port = os.environ['SLURM_JOB_ID']
+        default_port = default_port[-4:]
+
+        # all ports should be in the 10k+ range
+        default_port = int(default_port) + 15000
+
+    except Exception as e:
+        default_port = 12910
+
+    # if user gave a port number, use that one instead
+    try:
+        default_port = os.environ['MASTER_PORT']
+    except Exception:
+        os.environ['MASTER_PORT'] = str(default_port)
+
+    # figure out the root node addr
+    try:
+        root_node = os.environ['SLURM_NODELIST'].split(' ')[0]
+    except Exception:
+        root_node = '127.0.0.2'
+
+    root_node = self.trainer.resolve_root_node_address(root_node)
+    os.environ['MASTER_ADDR'] = root_node
+    dist.init_process_group('nccl', rank=self.proc_rank, world_size=self.world_size)
+```

docs/Trainer/index.md

@@ -1,5 +1,5 @@
 # Trainer
-[[Github Code](https://github.com/williamFalcon/pytorch-lightning/blob/master/pytorch_lightning/models/trainer.py)]
+[[Github Code](https://github.com/williamFalcon/pytorch-lightning/blob/master/pytorch_lightning/trainer/trainer.py)]
 
 The lightning trainer abstracts best practices for running a training, val, test routine. It calls parts of your model when it wants to hand over full control and otherwise makes training assumptions which are now standard practice in AI research.
 
@@ -19,56 +19,72 @@ But of course the fun is in all the advanced things it can do:
 
 **Checkpointing**    
 
-- Model saving
-- Model loading 
+- [Checkpoint callback](https://williamfalcon.github.io/pytorch-lightning/Trainer/Checkpointing/#model-saving)    
+- [Model saving](https://williamfalcon.github.io/pytorch-lightning/Trainer/Checkpointing/#model-saving)
+- [Model loading](https://williamfalcon.github.io/pytorch-lightning/LightningModule/methods/#load-from-metrics) 
+- [Restoring training session](https://williamfalcon.github.io/pytorch-lightning/Trainer/Checkpointing/#restoring-training-session)
 
 **Computing cluster (SLURM)**    
 
-- [Running grid search on a cluster](SLURM%20Managed%20Cluster/#running-grid-search-on-a-cluster)
-- [Walltime auto-resubmit](SLURM%20Managed%20Cluster/#walltime-auto-resubmit)   
+- [Running grid search on a cluster](https://williamfalcon.github.io/pytorch-lightning/Trainer/SLURM%20Managed%20Cluster#running-grid-search-on-a-cluster) 
+- [Walltime auto-resubmit](https://williamfalcon.github.io/pytorch-lightning/Trainer/SLURM%20Managed%20Cluster#walltime-auto-resubmit)   
 
 **Debugging**  
 
-- [Fast dev run](Debugging/#fast-dev-run)
-- [Inspect gradient norms](Debugging/#inspect-gradient-norms)
-- [Log GPU usage](Debugging/#Log-gpu-usage)
-- [Make model overfit on subset of data](Debugging/#make-model-overfit-on-subset-of-data)
-- [Print the parameter count by layer](Debugging/#print-the-parameter-count-by-layer)
-- [Pring which gradients are nan](Debugging/#print-which-gradients-are-nan)
+- [Fast dev run](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#fast-dev-run)
+- [Inspect gradient norms](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#inspect-gradient-norms)
+- [Log GPU usage](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#Log-gpu-usage)
+- [Make model overfit on subset of data](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#make-model-overfit-on-subset-of-data)
+- [Print the parameter count by layer](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#print-the-parameter-count-by-layer)
+- [Print which gradients are nan](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#print-which-gradients-are-nan)
+- [Print input and output size of every module in system](https://williamfalcon.github.io/pytorch-lightning/LightningModule/properties/#example_input_array)
 
 
 **Distributed training**    
 
-- [16-bit mixed precision](Distributed%20training/#16-bit-mixed-precision)
-- [Multi-GPU](Distributed%20training/#Multi-GPU)
-- [Multi-node](Distributed%20training/#Multi-node)
-- [Single GPU](Distributed%20training/#single-gpu)
-- [Self-balancing architecture](Distributed%20training/#self-balancing-architecture)
+- [Implement Your Own Distributed (DDP) training](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/#init_ddp_connection)
+- [16-bit mixed precision](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#16-bit-mixed-precision)
+- [Multi-GPU](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#Multi-GPU)
+- [Multi-node](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#Multi-node)
+- [Single GPU](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#single-gpu)
+- [Self-balancing architecture](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#self-balancing-architecture)
 
 
 **Experiment Logging**   
 
-- [Display metrics in progress bar](Logging/#display-metrics-in-progress-bar)
-- Log arbitrary metrics
-- [Log metric row every k batches](Logging/#log-metric-row-every-k-batches)
-- [Process position](Logging/#process-position)
-- [Save a snapshot of all hyperparameters](Logging/#save-a-snapshot-of-all-hyperparameters) 
-- [Snapshot code for a training run](Logging/#snapshot-code-for-a-training-run) 
-- [Write logs file to csv every k batches](Logging/#write-logs-file-to-csv-every-k-batches)
+- [Display metrics in progress bar](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#display-metrics-in-progress-bar)
+- [Log metric row every k batches](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#log-metric-row-every-k-batches)
+- [Process position](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#process-position)
+- [Tensorboard support](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#tensorboard-support)
+- [Save a snapshot of all hyperparameters](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#save-a-snapshot-of-all-hyperparameters) 
+- [Snapshot code for a training run](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#snapshot-code-for-a-training-run) 
+- [Write logs file to csv every k batches](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#write-logs-file-to-csv-every-k-batches)
 
 **Training loop**    
 
-- [Accumulate gradients](Training%20Loop/#accumulated-gradients)
-- [Anneal Learning rate](Training%20Loop/#anneal-learning-rate)
-- [Force training for min or max epochs](Training%20Loop/#force-training-for-min-or-max-epochs)
-- [Force disable early stop](Training%20Loop/#force-disable-early-stop)
-- [Use multiple optimizers (like GANs)](../Pytorch-lightning/LightningModule/#configure_optimizers)
-- [Set how much of the training set to check (1-100%)](Training%20Loop/#set-how-much-of-the-training-set-to-check)
+- [Accumulate gradients](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#accumulated-gradients)    
+- [Force training for min or max epochs](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#force-training-for-min-or-max-epochs)
+- [Early stopping callback](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#early-stopping)    
+- [Force disable early stop](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#force-disable-early-stop)
+- [Gradient Clipping](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#gradient-clipping)
+- [Hooks](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/)
+- [Learning rate scheduling](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/#configure_optimizers)
+- [Use multiple optimizers (like GANs)](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/#configure_optimizers)
+- [Set how much of the training set to check (1-100%)](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#set-how-much-of-the-training-set-to-check)
+- [Step optimizers at arbitrary intervals](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/#optimizer_step)
+- [Packed sequences](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#packed-sequences-as-inputs)
+- [Truncated Back Propagation Through Time](https://williamfalcon.github.io/pytorch-lightning//Training%20Loop/#truncated-back-propation-through-time)
 
 **Validation loop**    
 
-- [Check validation every n epochs](Validation%20Loop/#check-validation-every-n-epochs)
-- [Set how much of the validation set to check](Validation%20Loop/#set-how-much-of-the-validation-set-to-check)
-- [Set how much of the test set to check](Validation%20Loop/#set-how-much-of-the-test-set-to-check)
-- [Set validation check frequency within 1 training epoch](Validation%20Loop/#set-validation-check-frequency-within-1-training-epoch)
-- [Set the number of validation sanity steps](Validation%20Loop/#set-the-number-of-validation-sanity-steps)
+- [Check validation every n epochs](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#check-validation-every-n-epochs)
+- [Hooks](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/)
+- [Set how much of the validation set to check](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-how-much-of-the-validation-set-to-check)
+- [Set how much of the test set to check](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-how-much-of-the-test-set-to-check)
+- [Set validation check frequency within 1 training epoch](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-validation-check-frequency-within-1-training-epoch)
+- [Set the number of validation sanity steps](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-the-number-of-validation-sanity-steps)
+
+
+**Testing loop**    
+
+- [Run test set](https://williamfalcon.github.io/pytorch-lightning/Trainer/Testing%20loop/)  

docs/examples/Examples.md

@@ -1,9 +1,9 @@
 ### Template model definition
-In 99% of cases you want to just copy [this template](https://github.com/williamFalcon/pytorch-lightning/blob/master/examples/new_project_templates/lightning_module_template.py) to start a new lightningModule and change the core of what your model is actually trying to do.
+In 99% of cases you want to just copy [one of the examples](https://github.com/williamFalcon/pytorch-lightning/tree/master/pl_examples) to start a new lightningModule and change the core of what your model is actually trying to do.
 
 ```bash
 # get a copy of the module template
-wget https://github.com/williamFalcon/pytorch-lightning/blob/master/examples/new_project_templates/lightning_module_template.py
+wget https://raw.githubusercontent.com/williamFalcon/pytorch-lightning/master/pl_examples/new_project_templates/lightning_module_template.py
 ```
 
 ---    
@@ -40,64 +40,24 @@ The main function should have 3 arguments:
 - slurm_manager: Slurm cluster manager object (can be None)
 - dict: for you to return any values you want (useful in meta-learning, otherwise set to _)    
 
-```{}
+```python
 def main(hparams, cluster, results_dict):
     """
     Main training routine specific for this project
     :param hparams:
     :return:
     """
-    # init experiment
-    log_dir = os.path.dirname(os.path.realpath(__file__))
-    exp = Experiment(
-        name='test_tube_exp',
-        debug=True,
-        save_dir=log_dir,
-        version=0,
-        autosave=False,
-        description='test demo'
-    )
-    
-    # set the hparams for the experiment
-    exp.argparse(hparams)
-    exp.save()
-
     # build model
     model = MyLightningModule(hparams)
 
-    # callbacks
-    early_stop = EarlyStopping(
-        monitor=hparams.early_stop_metric,
-        patience=hparams.early_stop_patience,
-        verbose=True,
-        mode=hparams.early_stop_mode
-    )
-
-    model_save_path = '{}/{}/{}'.format(hparams.model_save_path, exp.name, exp.version)
-    checkpoint = ModelCheckpoint(
-        filepath=model_save_path,
-        save_function=None,
-        save_best_only=True,
-        verbose=True,
-        monitor=hparams.model_save_monitor_value,
-        mode=hparams.model_save_monitor_mode
-    )
-
     # configure trainer
-    trainer = Trainer(
-        experiment=exp,
-        cluster=cluster,
-        checkpoint_callback=checkpoint,
-        early_stop_callback=early_stop,
-    )
+    trainer = Trainer()
 
     # train model
     trainer.fit(model)
 ```
 
 
-
-
 The __main__ function will start training on your **main** function. If you use the HyperParameterOptimizer
 in hyper parameter optimization mode, this main function will get one set of hyperparameters. If you use it as a simple
 argument parser you get the default arguments in the argument parser.
@@ -159,7 +119,7 @@ def optimize_on_cluster(hyperparams):
     job_display_name = job_display_name[0:3]
 
     # run hopt
-    print('submitting jobs...')
+    logging.info('submitting jobs...')
     cluster.optimize_parallel_cluster_gpu(
         main,
         nb_trials=hyperparams.nb_hopt_trials,

docs/index.md

@@ -1,11 +1,67 @@
 ###### New project Quick Start    
-To start a new project define these two files.   
+To start a new project define two files, a LightningModule and a Trainer file.    
+To illustrate Lightning power and simplicity, here's an example of a typical research flow.    
 
-1. [Define a LightningModule](/pytorch-lightning/LightningModule/RequiredTrainerInterface/) 
-2. [Define a trainer](https://williamfalcon.github.io/pytorch-lightning/Trainer/)
-    - [Basic CPU Trainer Template](https://github.com/williamFalcon/pytorch-lightning/blob/master/pytorch_lightning/examples/new_project_templates/single_cpu_template.py) 
-    - [Multi-GPU Trainer Template](https://github.com/williamFalcon/pytorch-lightning/blob/master/pytorch_lightning/examples/new_project_templates/single_gpu_node_template.py)
-    - [GPU cluster Trainer Template](https://github.com/williamFalcon/pytorch-lightning/blob/master/pytorch_lightning/examples/new_project_templates/multi_node_cluster_template.py)
+###### Case 1: BERT    
+Let's say you're working on something like BERT but want to try different ways of training or even different networks.  
+You would define a single LightningModule and use flags to switch between your different ideas.   
+```python
+class BERT(pl.LightningModule):
+    def __init__(self, model_name, task):
+        self.task = task
+    
+        if model_name == 'transformer':
+            self.net = Transformer()
+        elif model_name == 'my_cool_version':
+            self.net = MyCoolVersion()
+            
+    def training_step(self, batch, batch_nb):
+        if self.task == 'standard_bert':
+            # do standard bert training with self.net...
+            # return loss
+            
+        if self.task == 'my_cool_task':
+            # do my own version with self.net
+            # return loss
+```   
+
+###### Case 2: COOLER NOT BERT    
+But if you wanted to try something **completely** different, you'd define a new module for that.    
+```python
+
+class CoolerNotBERT(pl.LightningModule):
+    def __init__(self):
+        self.net = ...
+        
+    def training_step(self, batch, batch_nb):
+        # do some other cool task
+        # return loss   
+```   
+
+###### Rapid research flow    
+Then you could do rapid research by switching between these two and using the same trainer.   
+```python
+
+if use_bert:
+    model = BERT()
+else:
+    model = CoolerNotBERT()
+    
+trainer = Trainer(gpus=4, use_amp=True)
+trainer.fit(model)
+```
+
+Notice a few things about this flow:   
+1. You're writing pure PyTorch... no unnecessary abstractions or new libraries to learn.   
+2. You get free GPU and 16-bit support without writing any of that code in your model.   
+3. You also get all of the capabilities below (without coding or testing yourself).     
+
+---    
+###### Templates 
+1. [MNIST LightningModule](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/#minimal-example) 
+2. [Trainer](https://williamfalcon.github.io/pytorch-lightning/Trainer/)
+    - [Basic CPU, GPU Trainer Template](https://github.com/williamFalcon/pytorch-lightning/tree/master/pl_examples/basic_examples)
+    - [GPU cluster Trainer Template](https://github.com/williamFalcon/pytorch-lightning/tree/master/pl_examples/multi_node_examples)
 
 ###### Docs shortcuts
 - [LightningModule](LightningModule/RequiredTrainerInterface/)  
@@ -20,8 +76,10 @@ To start a new project define these two files.
 
 ###### Checkpointing    
 
+- [Checkpoint callback](https://williamfalcon.github.io/pytorch-lightning/Trainer/Checkpointing/#model-saving)    
 - [Model saving](https://williamfalcon.github.io/pytorch-lightning/Trainer/Checkpointing/#model-saving)
 - [Model loading](https://williamfalcon.github.io/pytorch-lightning/LightningModule/methods/#load-from-metrics) 
+- [Restoring training session](https://williamfalcon.github.io/pytorch-lightning/Trainer/Checkpointing/#restoring-training-session)
 
 ###### Computing cluster (SLURM)    
 
@@ -36,10 +94,12 @@ To start a new project define these two files.
 - [Make model overfit on subset of data](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#make-model-overfit-on-subset-of-data)
 - [Print the parameter count by layer](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#print-the-parameter-count-by-layer)
 - [Pring which gradients are nan](https://williamfalcon.github.io/pytorch-lightning/Trainer/debugging/#print-which-gradients-are-nan)
+- [Print input and output size of every module in system](https://williamfalcon.github.io/pytorch-lightning/LightningModule/properties/#example_input_array)
 
 
 ###### Distributed training    
 
+- [Implement Your Own Distributed (DDP) training](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/#init_ddp_connection)
 - [16-bit mixed precision](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#16-bit-mixed-precision)
 - [Multi-GPU](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#Multi-GPU)
 - [Multi-node](https://williamfalcon.github.io/pytorch-lightning/Trainer/Distributed%20training/#Multi-node)
@@ -50,9 +110,9 @@ To start a new project define these two files.
 ###### Experiment Logging   
 
 - [Display metrics in progress bar](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#display-metrics-in-progress-bar)
-- Log arbitrary metrics
 - [Log metric row every k batches](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#log-metric-row-every-k-batches)
 - [Process position](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#process-position)
+- [Tensorboard support](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#tensorboard-support)
 - [Save a snapshot of all hyperparameters](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#save-a-snapshot-of-all-hyperparameters) 
 - [Snapshot code for a training run](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#snapshot-code-for-a-training-run) 
 - [Write logs file to csv every k batches](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#write-logs-file-to-csv-every-k-batches)
@@ -60,18 +120,24 @@ To start a new project define these two files.
 ###### Training loop    
 
 - [Accumulate gradients](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#accumulated-gradients)
-- [Anneal Learning rate](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#anneal-learning-rate)
 - [Force training for min or max epochs](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#force-training-for-min-or-max-epochs)
+- [Early stopping callback](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#early-stopping)    
 - [Force disable early stop](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#force-disable-early-stop)
 - [Gradient Clipping](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#gradient-clipping)
-- [Use multiple optimizers (like GANs)](https://williamfalcon.github.io/pytorch-lightning/Pytorch-Lightning/LightningModule/#configure_optimizers)
+- [Hooks](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/)
+- [Learning rate scheduling](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/#configure_optimizers)
+- [Use multiple optimizers (like GANs)](https://williamfalcon.github.io/pytorch-lightning/LightningModule/RequiredTrainerInterface/#configure_optimizers)
 - [Set how much of the training set to check (1-100%)](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#set-how-much-of-the-training-set-to-check)
+- [Step optimizers at arbitrary intervals](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/#optimizer_step)
 
-######Validation loop    
+###### Validation loop    
 
 - [Check validation every n epochs](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#check-validation-every-n-epochs)
+- [Hooks](https://williamfalcon.github.io/pytorch-lightning/Trainer/hooks/)
 - [Set how much of the validation set to check](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-how-much-of-the-validation-set-to-check)
 - [Set how much of the test set to check](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-how-much-of-the-test-set-to-check)
 - [Set validation check frequency within 1 training epoch](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-validation-check-frequency-within-1-training-epoch)
 - [Set the number of validation sanity steps](https://williamfalcon.github.io/pytorch-lightning/Trainer/Validation%20loop/#set-the-number-of-validation-sanity-steps)
 
+###### Testing loop  
+- [Run test set](https://williamfalcon.github.io/pytorch-lightning/Trainer/Testing%20loop/)  

docs/requirements.txt

@@ -1 +1,2 @@
 mkdocs-material==4.4.0
+mkdocs==1.0.4

mkdocs.yml

@@ -1,10 +1,16 @@
-site_name: Pytorch lightning Documentation
+site_name: PyTorch lightning Documentation
 theme:
   name: 'material'
 docs_dir: docs
+repo_name: 'williamFalcon/pytorch-lightning'
 repo_url: https://github.com/williamFalcon/pytorch-lightning
 site_dir: 'site'
-site_description: 'Documentation for Pytorch LightningModule, the researcher version of keras.'
+site_description: 'Documentation for PyTorch LightningModule, the researcher version of keras.'
 
 dev_addr: '0.0.0.0:8000'
 #google_analytics: ['UA-aasd', 'sitename']
+
+markdown_extensions:
+  - codehilite:
+      guess_lang: false
+      linenums: true

pl_examples/README.md

@@ -0,0 +1,11 @@
+# Examples   
+This folder has 3 sections:   
+
+### Domain templates   
+These are templates to show common approaches such as GANs and RL.   
+
+### Basic examples   
+These show the most common use of Lightning for either CPU or GPU training.   
+
+### Multi-node examples   
+These show how to run jobs on a GPU cluster using lightning.

pl_examples/__init__.py

@@ -0,0 +1,5 @@
+from .basic_examples.lightning_module_template import LightningTemplateModel
+
+__all__ = [
+    'LightningTemplateModel'
+]

pl_examples/basic_examples/README.md

@@ -0,0 +1,39 @@
+# Basic Examples   
+Use these examples to test how lightning works.   
+
+#### Test on CPU  
+```bash
+python cpu_template.py
+```
+
+---   
+#### Train on a single GPU
+```bash
+python gpu_template.py --gpus 1
+```   
+
+---    
+#### DataParallel (dp)   
+Train on multiple GPUs using DataParallel.
+
+```bash
+python gpu_template.py --gpus 2 --distributed_backend dp
+```   
+
+---
+#### DistributedDataParallel (ddp)    
+
+Train on multiple GPUs using DistributedDataParallel   
+```bash
+python gpu_template.py --gpus 2 --distributed_backend ddp
+```
+
+---
+#### DistributedDataParallel+DP (ddp2)    
+
+Train on multiple GPUs using DistributedDataParallel + dataparallel.
+On a single node, uses all GPUs for 1 model. Then shares gradient information
+across nodes.   
+```bash
+python gpu_template.py --gpus 2 --distributed_backend ddp2
+```

pl_examples/basic_examples/cpu_template.py

@@ -0,0 +1,54 @@
+"""
+Runs a model on a single node across N-gpus.
+"""
+import os
+from argparse import ArgumentParser
+
+import numpy as np
+import torch
+
+from pl_examples.basic_examples.lightning_module_template import LightningTemplateModel
+from pytorch_lightning import Trainer
+
+SEED = 2334
+torch.manual_seed(SEED)
+np.random.seed(SEED)
+
+
+def main(hparams):
+    """
+    Main training routine specific for this project
+    :param hparams:
+    """
+    # ------------------------
+    # 1 INIT LIGHTNING MODEL
+    # ------------------------
+    model = LightningTemplateModel(hparams)
+
+    # ------------------------
+    # 2 INIT TRAINER
+    # ------------------------
+    trainer = Trainer()
+
+    # ------------------------
+    # 3 START TRAINING
+    # ------------------------
+    trainer.fit(model)
+
+
+if __name__ == '__main__':
+    # ------------------------
+    # TRAINING ARGUMENTS
+    # ------------------------
+    # these are project-wide arguments
+    root_dir = os.path.dirname(os.path.realpath(__file__))
+    parent_parser = ArgumentParser(add_help=False)
+
+    # each LightningModule defines arguments relevant to it
+    parser = LightningTemplateModel.add_model_specific_args(parent_parser, root_dir)
+    hyperparams = parser.parse_args()
+
+    # ---------------------
+    # RUN TRAINING
+    # ---------------------
+    main(hyperparams)

pl_examples/basic_examples/gpu_template.py

@@ -0,0 +1,79 @@
+"""
+Runs a model on a single node across N-gpus.
+"""
+import os
+from argparse import ArgumentParser
+
+import numpy as np
+import torch
+
+from pl_examples.basic_examples.lightning_module_template import LightningTemplateModel
+from pytorch_lightning import Trainer
+
+SEED = 2334
+torch.manual_seed(SEED)
+np.random.seed(SEED)
+
+
+def main(hparams):
+    """
+    Main training routine specific for this project
+    :param hparams:
+    """
+    # ------------------------
+    # 1 INIT LIGHTNING MODEL
+    # ------------------------
+    model = LightningTemplateModel(hparams)
+
+    # ------------------------
+    # 2 INIT TRAINER
+    # ------------------------
+    trainer = Trainer(
+        gpus=hparams.gpus,
+        distributed_backend=hparams.distributed_backend,
+        use_amp=hparams.use_16bit
+    )
+
+    # ------------------------
+    # 3 START TRAINING
+    # ------------------------
+    trainer.fit(model)
+
+
+if __name__ == '__main__':
+    # ------------------------
+    # TRAINING ARGUMENTS
+    # ------------------------
+    # these are project-wide arguments
+
+    root_dir = os.path.dirname(os.path.realpath(__file__))
+    parent_parser = ArgumentParser(add_help=False)
+
+    # gpu args
+    parent_parser.add_argument(
+        '--gpus',
+        type=int,
+        default=2,
+        help='how many gpus'
+    )
+    parent_parser.add_argument(
+        '--distributed_backend',
+        type=str,
+        default='dp',
+        help='supports three options dp, ddp, ddp2'
+    )
+    parent_parser.add_argument(
+        '--use_16bit',
+        dest='use_16bit',
+        action='store_true',
+        help='if true uses 16 bit precision'
+    )
+
+    # each LightningModule defines arguments relevant to it
+    parser = LightningTemplateModel.add_model_specific_args(parent_parser, root_dir)
+    hyperparams = parser.parse_args()
+
+    # ---------------------
+    # RUN TRAINING
+    # ---------------------
+    main(hyperparams)

pl_examples/basic_examples/lightning_module_template.py

@@ -1,16 +1,21 @@
+"""
+Example template for defining a system
+"""
 import os
+import logging
+from argparse import ArgumentParser
 from collections import OrderedDict
-import torch.nn as nn
-from torchvision.datasets import MNIST
-import torchvision.transforms as transforms
+
 import torch
+import torch.nn as nn
 import torch.nn.functional as F
-from test_tube import HyperOptArgumentParser
+import torchvision.transforms as transforms
 from torch import optim
 from torch.utils.data import DataLoader
 from torch.utils.data.distributed import DistributedSampler
+from torchvision.datasets import MNIST
 
-import pytorch_lightning as ptl
+import pytorch_lightning as pl
 from pytorch_lightning.root_module.root_module import LightningModule
 
 
@@ -44,11 +49,13 @@ class LightningTemplateModel(LightningModule):
         Layout model
         :return:
         """
-        self.c_d1 = nn.Linear(in_features=self.hparams.in_features, out_features=self.hparams.hidden_dim)
+        self.c_d1 = nn.Linear(in_features=self.hparams.in_features,
+                              out_features=self.hparams.hidden_dim)
         self.c_d1_bn = nn.BatchNorm1d(self.hparams.hidden_dim)
         self.c_d1_drop = nn.Dropout(self.hparams.drop_prob)
 
-        self.c_d2 = nn.Linear(in_features=self.hparams.hidden_dim, out_features=self.hparams.out_features)
+        self.c_d2 = nn.Linear(in_features=self.hparams.hidden_dim,
+                              out_features=self.hparams.out_features)
 
     # ---------------------
     # TRAINING
@@ -74,14 +81,14 @@ class LightningTemplateModel(LightningModule):
         nll = F.nll_loss(logits, labels)
         return nll
 
-    def training_step(self, data_batch, batch_i):
+    def training_step(self, batch, batch_idx):
         """
         Lightning calls this inside the training loop
-        :param data_batch:
+        :param batch:
         :return:
         """
         # forward pass
-        x, y = data_batch
+        x, y = batch
         x = x.view(x.size(0), -1)
 
         y_hat = self.forward(x)
@@ -90,23 +97,26 @@ class LightningTemplateModel(LightningModule):
         loss_val = self.loss(y, y_hat)
 
         # in DP mode (default) make sure if result is scalar, there's another dim in the beginning
-        if self.trainer.use_dp:
+        if self.trainer.use_dp or self.trainer.use_ddp2:
             loss_val = loss_val.unsqueeze(0)
 
+        tqdm_dict = {'train_loss': loss_val}
         output = OrderedDict({
-            'loss': loss_val
+            'loss': loss_val,
+            'progress_bar': tqdm_dict,
+            'log': tqdm_dict
         })
 
         # can also return just a scalar instead of a dict (return loss_val)
         return output
 
-    def validation_step(self, data_batch, batch_i):
+    def validation_step(self, batch, batch_idx):
         """
         Lightning calls this inside the validation loop
-        :param data_batch:
+        :param batch:
         :return:
         """
-        x, y = data_batch
+        x, y = batch
         x = x.view(x.size(0), -1)
         y_hat = self.forward(x)
 
@@ -121,7 +131,7 @@ class LightningTemplateModel(LightningModule):
             val_acc = val_acc.cuda(loss_val.device.index)
 
         # in DP mode (default) make sure if result is scalar, there's another dim in the beginning
-        if self.trainer.use_dp:
+        if self.trainer.use_dp or self.trainer.use_ddp2:
             loss_val = loss_val.unsqueeze(0)
             val_acc = val_acc.unsqueeze(0)
 
@@ -146,13 +156,25 @@ class LightningTemplateModel(LightningModule):
         val_loss_mean = 0
         val_acc_mean = 0
         for output in outputs:
-            val_loss_mean += output['val_loss']
-            val_acc_mean += output['val_acc']
+            val_loss = output['val_loss']
+
+            # reduce manually when using dp
+            if self.trainer.use_dp or self.trainer.use_ddp2:
+                val_loss = torch.mean(val_loss)
+            val_loss_mean += val_loss
+
+            # reduce manually when using dp
+            val_acc = output['val_acc']
+            if self.trainer.use_dp or self.trainer.use_ddp2:
+                val_acc = torch.mean(val_acc)
+
+            val_acc_mean += val_acc
 
         val_loss_mean /= len(outputs)
         val_acc_mean /= len(outputs)
-        tqdm_dic = {'val_loss': val_loss_mean.item(), 'val_acc': val_acc_mean.item()}
-        return tqdm_dic
+        tqdm_dict = {'val_loss': val_loss_mean, 'val_acc': val_acc_mean}
+        result = {'progress_bar': tqdm_dict, 'log': tqdm_dict, 'val_loss': val_loss_mean}
+        return result
 
     # ---------------------
     # TRAINING SETUP
@@ -163,77 +185,74 @@ class LightningTemplateModel(LightningModule):
         :return: list of optimizers
         """
         optimizer = optim.Adam(self.parameters(), lr=self.hparams.learning_rate)
-        return [optimizer]
+        scheduler = optim.lr_scheduler.CosineAnnealingLR(optimizer, T_max=10)
+        return [optimizer], [scheduler]
 
     def __dataloader(self, train):
         # init data generators
-        transform = transforms.Compose([transforms.ToTensor(), transforms.Normalize((0.5,), (1.0,))])
-        dataset = MNIST(root=self.hparams.data_root, train=train, transform=transform, download=True)
+        transform = transforms.Compose([transforms.ToTensor(),
+                                        transforms.Normalize((0.5,), (1.0,))])
+        dataset = MNIST(root=self.hparams.data_root, train=train,
+                        transform=transform, download=True)
 
-        # when using multi-node we need to add the datasampler
+        # when using multi-node (ddp) we need to add the  datasampler
         train_sampler = None
         batch_size = self.hparams.batch_size
 
-        try:
-            if self.on_gpu:
-                train_sampler = DistributedSampler(dataset, rank=self.trainer.proc_rank)
-                batch_size = batch_size // self.trainer.world_size  # scale batch size
-        except Exception as e:
-            pass
+        if self.use_ddp:
+            train_sampler = DistributedSampler(dataset)
 
         should_shuffle = train_sampler is None
         loader = DataLoader(
             dataset=dataset,
             batch_size=batch_size,
             shuffle=should_shuffle,
-            sampler=train_sampler
+            sampler=train_sampler,
+            num_workers=0
         )
 
         return loader
 
-    @ptl.data_loader
-    def tng_dataloader(self):
-        print('tng data loader called')
+    @pl.data_loader
+    def train_dataloader(self):
+        logging.info('training data loader called')
         return self.__dataloader(train=True)
 
-    @ptl.data_loader
+    @pl.data_loader
     def val_dataloader(self):
-        print('val data loader called')
+        logging.info('val data loader called')
         return self.__dataloader(train=False)
 
-    @ptl.data_loader
+    @pl.data_loader
     def test_dataloader(self):
-        print('test data loader called')
+        logging.info('test data loader called')
         return self.__dataloader(train=False)
 
     @staticmethod
-    def add_model_specific_args(parent_parser, root_dir): # pragma: no cover
+    def add_model_specific_args(parent_parser, root_dir):  # pragma: no cover
         """
         Parameters you define here will be available to your model through self.hparams
         :param parent_parser:
         :param root_dir:
         :return:
         """
-        parser = HyperOptArgumentParser(strategy=parent_parser.strategy, parents=[parent_parser])
+        parser = ArgumentParser(parents=[parent_parser])
 
         # param overwrites
-        # parser.set_defaults(gradient_clip=5.0)
+        # parser.set_defaults(gradient_clip_val=5.0)
 
         # network params
-        parser.opt_list('--drop_prob', default=0.2, options=[0.2, 0.5], type=float, tunable=False)
-        parser.add_argument('--in_features', default=28*28, type=int)
+        parser.add_argument('--in_features', default=28 * 28, type=int)
         parser.add_argument('--out_features', default=10, type=int)
-        parser.add_argument('--hidden_dim', default=50000, type=int) # use 500 for CPU, 50000 for GPU to see speed difference
+        # use 500 for CPU, 50000 for GPU to see speed difference
+        parser.add_argument('--hidden_dim', default=50000, type=int)
+        parser.add_argument('--drop_prob', default=0.2, type=float)
+        parser.add_argument('--learning_rate', default=0.001, type=float)
 
         # data
         parser.add_argument('--data_root', default=os.path.join(root_dir, 'mnist'), type=str)
 
         # training params (opt)
-        parser.opt_list('--learning_rate', default=0.001*8, type=float, options=[0.0001, 0.0005, 0.001, 0.005],
-                        tunable=False)
-        parser.opt_list('--optimizer_name', default='adam', type=str, options=['adam'], tunable=False)
-
-        # if using 2 nodes with 4 gpus each the batch size here (256) will be 256 / (2*8) = 16 per gpu
-        parser.opt_list('--batch_size', default=256*8, type=int, options=[32, 64, 128, 256], tunable=False,
-                        help='batch size will be divided over all the gpus being used across all nodes')
+        parser.add_argument('--optimizer_name', default='adam', type=str)
+        parser.add_argument('--batch_size', default=64, type=int)
         return parser

pl_examples/domain_templates/gan.py

@@ -0,0 +1,208 @@
+"""
+To run this template just do:
+python gan.py
+
+After a few epochs, launch tensorboard to see the images being generated at every batch.
+
+tensorboard --logdir default
+"""
+import os
+from argparse import ArgumentParser
+from collections import OrderedDict
+
+import numpy as np
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+import torchvision
+import torchvision.transforms as transforms
+from torch.utils.data import DataLoader
+from torchvision.datasets import MNIST
+
+import pytorch_lightning as pl
+
+
+class Generator(nn.Module):
+    def __init__(self, latent_dim, img_shape):
+        super(Generator, self).__init__()
+        self.img_shape = img_shape
+
+        def block(in_feat, out_feat, normalize=True):
+            layers = [nn.Linear(in_feat, out_feat)]
+            if normalize:
+                layers.append(nn.BatchNorm1d(out_feat, 0.8))
+            layers.append(nn.LeakyReLU(0.2, inplace=True))
+            return layers
+
+        self.model = nn.Sequential(
+            *block(latent_dim, 128, normalize=False),
+            *block(128, 256),
+            *block(256, 512),
+            *block(512, 1024),
+            nn.Linear(1024, int(np.prod(img_shape))),
+            nn.Tanh()
+        )
+
+    def forward(self, z):
+        img = self.model(z)
+        img = img.view(img.size(0), *self.img_shape)
+        return img
+
+
+class Discriminator(nn.Module):
+    def __init__(self, img_shape):
+        super(Discriminator, self).__init__()
+
+        self.model = nn.Sequential(
+            nn.Linear(int(np.prod(img_shape)), 512),
+            nn.LeakyReLU(0.2, inplace=True),
+            nn.Linear(512, 256),
+            nn.LeakyReLU(0.2, inplace=True),
+            nn.Linear(256, 1),
+            nn.Sigmoid(),
+        )
+
+    def forward(self, img):
+        img_flat = img.view(img.size(0), -1)
+        validity = self.model(img_flat)
+
+        return validity
+
+
+class GAN(pl.LightningModule):
+
+    def __init__(self, hparams):
+        super(GAN, self).__init__()
+        self.hparams = hparams
+
+        # networks
+        mnist_shape = (1, 28, 28)
+        self.generator = Generator(latent_dim=hparams.latent_dim, img_shape=mnist_shape)
+        self.discriminator = Discriminator(img_shape=mnist_shape)
+
+        # cache for generated images
+        self.generated_imgs = None
+        self.last_imgs = None
+
+    def forward(self, z):
+        return self.generator(z)
+
+    def adversarial_loss(self, y_hat, y):
+        return F.binary_cross_entropy(y_hat, y)
+
+    def training_step(self, batch, batch_nb, optimizer_i):
+        imgs, _ = batch
+        self.last_imgs = imgs
+
+        # train generator
+        if optimizer_i == 0:
+            # sample noise
+            z = torch.randn(imgs.shape[0], self.hparams.latent_dim)
+
+            # match gpu device (or keep as cpu)
+            if self.on_gpu:
+                z = z.cuda(imgs.device.index)
+
+            # generate images
+            self.generated_imgs = self.forward(z)
+
+            # log sampled images
+            # sample_imgs = self.generated_imgs[:6]
+            # grid = torchvision.utils.make_grid(sample_imgs)
+            # self.logger.experiment.add_image('generated_images', grid, 0)
+
+            # ground truth result (ie: all fake)
+            valid = torch.ones(imgs.size(0), 1)
+
+            # adversarial loss is binary cross-entropy
+            g_loss = self.adversarial_loss(self.discriminator(self.generated_imgs), valid)
+            tqdm_dict = {'g_loss': g_loss}
+            output = OrderedDict({
+                'loss': g_loss,
+                'progress_bar': tqdm_dict,
+                'log': tqdm_dict
+            })
+            return output
+
+        # train discriminator
+        if optimizer_i == 1:
+            # Measure discriminator's ability to classify real from generated samples
+
+            # how well can it label as real?
+            valid = torch.ones(imgs.size(0), 1)
+            real_loss = self.adversarial_loss(self.discriminator(imgs), valid)
+
+            # how well can it label as fake?
+            fake = torch.zeros(imgs.size(0), 1)
+            fake_loss = self.adversarial_loss(
+                self.discriminator(self.generated_imgs.detach()), fake)
+
+            # discriminator loss is the average of these
+            d_loss = (real_loss + fake_loss) / 2
+            tqdm_dict = {'d_loss': d_loss}
+            output = OrderedDict({
+                'loss': d_loss,
+                'progress_bar': tqdm_dict,
+                'log': tqdm_dict
+            })
+            return output
+
+    def configure_optimizers(self):
+        lr = self.hparams.lr
+        b1 = self.hparams.b1
+        b2 = self.hparams.b2
+
+        opt_g = torch.optim.Adam(self.generator.parameters(), lr=lr, betas=(b1, b2))
+        opt_d = torch.optim.Adam(self.discriminator.parameters(), lr=lr, betas=(b1, b2))
+        return [opt_g, opt_d], []
+
+    @pl.data_loader
+    def train_dataloader(self):
+        transform = transforms.Compose([transforms.ToTensor(),
+                                        transforms.Normalize([0.5], [0.5])])
+        dataset = MNIST(os.getcwd(), train=True, download=True, transform=transform)
+        return DataLoader(dataset, batch_size=self.hparams.batch_size)
+
+    def on_epoch_end(self):
+        z = torch.randn(8, self.hparams.latent_dim)
+        # match gpu device (or keep as cpu)
+        if self.on_gpu:
+            z = z.cuda(self.last_imgs.device.index)
+
+        # log sampled images
+        sample_imgs = self.forward(z)
+        grid = torchvision.utils.make_grid(sample_imgs)
+        self.logger.experiment.add_image(f'generated_images', grid, self.current_epoch)
+
+
+def main(hparams):
+    # ------------------------
+    # 1 INIT LIGHTNING MODEL
+    # ------------------------
+    model = GAN(hparams)
+
+    # ------------------------
+    # 2 INIT TRAINER
+    # ------------------------
+    trainer = pl.Trainer()
+
+    # ------------------------
+    # 3 START TRAINING
+    # ------------------------
+    trainer.fit(model)
+
+
+if __name__ == '__main__':
+    parser = ArgumentParser()
+    parser.add_argument("--batch_size", type=int, default=64, help="size of the batches")
+    parser.add_argument("--lr", type=float, default=0.0002, help="adam: learning rate")
+    parser.add_argument("--b1", type=float, default=0.5,
+                        help="adam: decay of first order momentum of gradient")
+    parser.add_argument("--b2", type=float, default=0.999,
+                        help="adam: decay of first order momentum of gradient")
+    parser.add_argument("--latent_dim", type=int, default=100,
+                        help="dimensionality of the latent space")
+
+    hparams = parser.parse_args()
+
+    main(hparams)

pl_examples/multi_node_examples/README.md

@@ -0,0 +1,21 @@
+# Multi-node example   
+
+This demo launches a job using 2 GPUs on 2 different nodes (4 GPUs total).
+To run this demo do the following:
+
+1. Log into the jumphost node of your SLURM-managed cluster.  
+2. Create a conda environment with Lightning and a GPU PyTorch version.   
+3. Choose a script to submit    
+
+#### DDP  
+Submit this job to run with distributedDataParallel (2 nodes, 2 gpus each)
+```bash
+sbatch ddp_job_submit.sh YourEnv
+```
+
+#### DDP2  
+Submit this job to run with a different implementation of distributedDataParallel.
+In this version, each node acts like DataParallel but syncs across nodes like DDP.
+```bash
+sbatch ddp2_job_submit.sh YourEnv
+```

pl_examples/multi_node_examples/ddp2_job_submit.sh

@@ -0,0 +1,27 @@
+#!/bin/bash -l
+
+# SLURM SUBMIT SCRIPT
+#SBATCH --nodes=2
+#SBATCH --gres=gpu:2
+#SBATCH --ntasks-per-node=1
+#SBATCH --mem=0
+#SBATCH --time=0-02:00:00
+
+# activate conda env
+source activate $1
+
+# -------------------------
+# debugging flags (optional)
+ export NCCL_DEBUG=INFO
+ export PYTHONFAULTHANDLER=1
+
+# on your cluster you might need these:
+# set the network interface
+# export NCCL_SOCKET_IFNAME=^docker0,lo
+
+# might need the latest cuda
+# module load NCCL/2.4.7-1-cuda.10.0
+# -------------------------
+
+# run script from above
+srun python3 multi_node_ddp2_demo.py

pl_examples/multi_node_examples/ddp_job_submit.sh

@@ -0,0 +1,27 @@
+#!/bin/bash -l
+
+# SLURM SUBMIT SCRIPT
+#SBATCH --nodes=2
+#SBATCH --gres=gpu:2
+#SBATCH --ntasks-per-node=2
+#SBATCH --mem=0
+#SBATCH --time=0-02:00:00
+
+# activate conda env
+source activate $1
+
+# -------------------------
+# debugging flags (optional)
+ export NCCL_DEBUG=INFO
+ export PYTHONFAULTHANDLER=1
+
+# on your cluster you might need these:
+# set the network interface
+# export NCCL_SOCKET_IFNAME=^docker0,lo
+
+# might need the latest cuda
+# module load NCCL/2.4.7-1-cuda.10.0
+# -------------------------
+
+# run script from above
+srun python3 multi_node_ddp_demo.py

pl_examples/multi_node_examples/multi_node_ddp2_demo.py

@@ -0,0 +1,55 @@
+"""
+Multi-node example (GPU)
+"""
+import os
+from argparse import ArgumentParser
+
+import numpy as np
+import torch
+
+from pl_examples.basic_examples.lightning_module_template import LightningTemplateModel
+from pytorch_lightning import Trainer
+
+SEED = 2334
+torch.manual_seed(SEED)
+np.random.seed(SEED)
+
+
+def main(hparams):
+    """
+    Main training routine specific for this project
+    :param hparams:
+    :return:
+    """
+    # ------------------------
+    # 1 INIT LIGHTNING MODEL
+    # ------------------------
+    model = LightningTemplateModel(hparams)
+
+    # ------------------------
+    # 2 INIT TRAINER
+    # ------------------------
+    trainer = Trainer(
+        gpus=2,
+        nb_gpu_nodes=2,
+        distributed_backend='ddp2'
+    )
+
+    # ------------------------
+    # 3 START TRAINING
+    # ------------------------
+    trainer.fit(model)
+
+
+if __name__ == '__main__':
+    root_dir = os.path.dirname(os.path.realpath(__file__))
+    parent_parser = ArgumentParser(add_help=False)
+
+    # each LightningModule defines arguments relevant to it
+    parser = LightningTemplateModel.add_model_specific_args(parent_parser, root_dir)
+    hyperparams = parser.parse_args()
+
+    # ---------------------
+    # RUN TRAINING
+    # ---------------------
+    main(hyperparams)

pl_examples/multi_node_examples/multi_node_ddp_demo.py

@@ -0,0 +1,55 @@
+"""
+Multi-node example (GPU)
+"""
+import os
+from argparse import ArgumentParser
+
+import numpy as np
+import torch
+
+from pl_examples.basic_examples.lightning_module_template import LightningTemplateModel
+from pytorch_lightning import Trainer
+
+SEED = 2334
+torch.manual_seed(SEED)
+np.random.seed(SEED)
+
+
+def main(hparams):
+    """
+    Main training routine specific for this project
+    :param hparams:
+    :return:
+    """
+    # ------------------------
+    # 1 INIT LIGHTNING MODEL
+    # ------------------------
+    model = LightningTemplateModel(hparams)
+
+    # ------------------------
+    # 2 INIT TRAINER
+    # ------------------------
+    trainer = Trainer(
+        gpus=2,
+        nb_gpu_nodes=2,
+        distributed_backend='ddp'
+    )
+
+    # ------------------------
+    # 3 START TRAINING
+    # ------------------------
+    trainer.fit(model)
+
+
+if __name__ == '__main__':
+    root_dir = os.path.dirname(os.path.realpath(__file__))
+    parent_parser = ArgumentParser(add_help=False)
+
+    # each LightningModule defines arguments relevant to it
+    parser = LightningTemplateModel.add_model_specific_args(parent_parser, root_dir)
+    hyperparams = parser.parse_args()
+
+    # ---------------------
+    # RUN TRAINING
+    # ---------------------
+    main(hyperparams)

pytorch_lightning/__init__.py

@@ -1,3 +1,36 @@
-from .models import Trainer
-from .root_module.root_module import LightningModule
-from .root_module.decorators import data_loader
+"""Package info"""
+
+__version__ = '0.5.3'
+__author__ = ' William Falcon et al.'
+__author_email__ = 'waf2107@columbia.edu'
+__license__ = 'Apache-2.0'
+__homepage__ = 'https://github.com/williamFalcon/pytorch-lightning',
+__docs__ = """# PyTorch Lightning
+
+The lightweight PyTorch wrapper for ML researchers. Scale your models. Write less boilerplate.
+"""
+
+
+try:
+    # This variable is injected in the __builtins__ by the build
+    # process. It used to enable importing subpackages of skimage when
+    # the binaries are not built
+    __LIGHTNING_SETUP__
+except NameError:
+    __LIGHTNING_SETUP__ = False
+
+if __LIGHTNING_SETUP__:
+    import sys
+    sys.stderr.write('Partial import of skimage during the build process.\n')
+    # We are not importing the rest of the scikit during the build
+    # process, as it may not be compiled yet
+else:
+    from .trainer.trainer import Trainer
+    from .root_module.root_module import LightningModule
+    from .root_module.decorators import data_loader
+
+    __all__ = [
+        'Trainer',
+        'LightningModule',
+        'data_loader',
+    ]

pytorch_lightning/callbacks/__init__.py

@@ -1 +1,7 @@
-from .pt_callbacks import EarlyStopping, ModelCheckpoint
+from .pt_callbacks import EarlyStopping, ModelCheckpoint, GradientAccumulationScheduler
+
+__all__ = [
+    'EarlyStopping',
+    'ModelCheckpoint',
+    'GradientAccumulationScheduler',
+]

pytorch_lightning/callbacks/pt_callbacks.py

@@ -1,5 +1,9 @@
+import os
+import shutil
+import logging
+import warnings
 import numpy as np
-import os, shutil
+
 from pytorch_lightning.pt_overrides.override_data_parallel import LightningDistributedDataParallel
 
 
@@ -8,7 +12,6 @@ class Callback(object):
     # Properties
         params: dict. Training parameters
             (eg. verbosity, batch size, number of epochs...).
-        model: instance of `keras.models.Model`.
             Reference of the model being trained.
     The `logs` dictionary that callback methods
     take as argument will contain keys for quantities relevant to
@@ -89,7 +92,7 @@ class EarlyStopping(Callback):
         self.stopped_epoch = 0
 
         if mode not in ['auto', 'min', 'max']:
-            print('EarlyStopping mode %s is unknown, fallback to auto mode.' % mode)
+            logging.info(f'EarlyStopping mode {mode} is unknown, fallback to auto mode.')
             mode = 'auto'
 
         if mode == 'min':
@@ -119,10 +122,12 @@ class EarlyStopping(Callback):
         current = logs.get(self.monitor)
         stop_training = False
         if current is None:
-            print('Early stopping conditioned on metric `%s` ''which is not available. Available metrics are: %s' %
-                (self.monitor, ','.join(list(logs.keys()))), RuntimeWarning
-            )
-            exit(-1)
+            warnings.warn(
+                f'Early stopping conditioned on metric `{self.monitor}`'
+                f' which is not available. Available metrics are: {",".join(list(logs.keys()))}',
+                RuntimeWarning)
+            stop_training = True
+            return stop_training
 
         if self.monitor_op(current - self.min_delta, self.best):
             self.best = current
@@ -138,7 +143,7 @@ class EarlyStopping(Callback):
 
     def on_train_end(self, logs=None):
         if self.stopped_epoch > 0 and self.verbose > 0:
-            print('Epoch %05d: early stopping' % (self.stopped_epoch + 1))
+            logging.info(f'Epoch {self.stopped_epoch + 1:05d}: early stopping')
 
 
 class ModelCheckpoint(Callback):
@@ -171,9 +176,19 @@ class ModelCheckpoint(Callback):
     """
 
     def __init__(self, filepath, monitor='val_loss', verbose=0,
-                 save_best_only=False, save_weights_only=False,
+                 save_best_only=True, save_weights_only=False,
                  mode='auto', period=1, prefix=''):
         super(ModelCheckpoint, self).__init__()
+        if (
+            save_best_only and
+            os.path.isdir(filepath) and
+            len(os.listdir(filepath)) > 0
+        ):
+            warnings.warn(
+                f"Checkpoint directory {filepath} exists and is not empty with save_best_only=True."
+                "All files in this directory will be deleted when a checkpoint is saved!"
+            )
+
         self.monitor = monitor
         self.verbose = verbose
         self.filepath = filepath
@@ -184,9 +199,9 @@ class ModelCheckpoint(Callback):
         self.prefix = prefix
 
         if mode not in ['auto', 'min', 'max']:
-            print('ModelCheckpoint mode %s is unknown, '
-                          'fallback to auto mode.' % (mode),
-                          RuntimeWarning)
+            warnings.warn(
+                f'ModelCheckpoint mode {mode} is unknown, '
+                'fallback to auto mode.', RuntimeWarning)
             mode = 'auto'
 
         if mode == 'min':
@@ -230,34 +245,66 @@ class ModelCheckpoint(Callback):
             if self.save_best_only:
                 current = logs.get(self.monitor)
                 if current is None:
-                    print('Can save best model only with %s available, '
-                                  'skipping.' % (self.monitor), RuntimeWarning)
+                    warnings.warn(
+                        f'Can save best model only with {self.monitor} available,'
+                        ' skipping.', RuntimeWarning)
                 else:
                     if self.monitor_op(current, self.best):
                         if self.verbose > 0:
-                            print('\nEpoch %05d: %s improved from %0.5f to %0.5f,'
-                                  ' saving model to %s'
-                                  % (epoch + 1, self.monitor, self.best,
-                                     current, filepath))
+                            logging.info(
+                                f'\nEpoch {epoch + 1:05d}: {self.monitor} improved'
+                                f' from {self.best:0.5f} to {current:0.5f},',
+                                f' saving model to {filepath}')
                         self.best = current
                         self.save_model(filepath, overwrite=True)
 
                     else:
                         if self.verbose > 0:
-                            print('\nEpoch %05d: %s did not improve' %
-                                  (epoch + 1, self.monitor))
+                            logging.info(
+                                f'\nEpoch {epoch + 1:05d}: {self.monitor} did not improve')
             else:
                 if self.verbose > 0:
-                    print('\nEpoch %05d: saving model to %s' % (epoch + 1, filepath))
+                    logging.info(f'\nEpoch {epoch + 1:05d}: saving model to {filepath}')
                 self.save_model(filepath, overwrite=False)
 
 
+class GradientAccumulationScheduler(Callback):
+    """Change gradient accumulation factor according to scheduling.
+    # Arguments
+        scheduling: dict, scheduling in format {epoch: accumulation_factor}
+    """
+
+    def __init__(self, scheduling: dict):
+        if scheduling == {}:  # empty dict error
+            raise TypeError("Empty dict cannot be interpreted correct")
+
+        for key in scheduling.keys():
+            if not isinstance(key, int) or not isinstance(scheduling[key], int):
+                raise TypeError("All epoches and accumulation factor must be integers")
+
+        minimal_epoch = min(scheduling.keys())
+        if minimal_epoch < 1:
+            msg = f"Epochs indexing from 1, epoch {minimal_epoch} cannot be interpreted correct"
+            raise IndexError(msg)
+        elif minimal_epoch != 1:  # if user didnt define first epoch accumulation factor
+            scheduling.update({1: 1})
+
+        self.scheduling = scheduling
+        self.epochs = sorted(scheduling.keys())
+
+    def on_epoch_begin(self, epoch, trainer):
+        epoch += 1  # indexing epochs from 1
+        for i in reversed(range(len(self.epochs))):
+            if epoch >= self.epochs[i]:
+                trainer.accumulate_grad_batches = self.scheduling.get(self.epochs[i])
+                break
+
+
 if __name__ == '__main__':
     c = EarlyStopping(min_delta=0.9, patience=2, verbose=True)
     losses = [10, 9, 8, 8, 6, 4.3, 5, 4.4, 2.8, 2.5]
     for i, loss in enumerate(losses):
         should_stop = c.on_epoch_end(i, logs={'val_loss': loss})
-        print(loss)
+        logging.info(loss)
         if should_stop:
             break
-

pytorch_lightning/examples/__init__.py

@@ -1 +0,0 @@
-from .new_project_templates.lightning_module_template import LightningTemplateModel

pytorch_lightning/examples/new_project_templates/multi_node_cluster_template.py

@@ -1,172 +0,0 @@
-import os
-import sys
-import numpy as np
-from time import sleep
-import torch
-
-from test_tube import HyperOptArgumentParser, Experiment, SlurmCluster
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.utils.arg_parse import add_default_args
-
-from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint
-
-SEED = 2334
-torch.manual_seed(SEED)
-np.random.seed(SEED)
-
-# ---------------------
-# DEFINE MODEL HERE
-# ---------------------
-from lightning_module_template import LightningTemplateModel
-# ---------------------
-
-"""
-Allows training by using command line arguments
-Run by:
-# TYPE YOUR RUN COMMAND HERE
-"""
-
-
-def main_local(hparams):
-    main(hparams, None, None)
-
-
-def main(hparams, cluster, results_dict):
-    """
-    Main training routine specific for this project
-    :param hparams:
-    :return:
-    """
-    # ------------------------
-    # 1 INIT LIGHTNING MODEL
-    # ------------------------
-    print('loading model...')
-    model = LightningTemplateModel(hparams)
-    print('model built')
-
-    # ------------------------
-    # 2 INIT TEST TUBE EXP
-    # ------------------------
-    # when using grid search, it's possible for all models to start at once
-    # and use the same test tube experiment version
-    relative_node_id = int(os.environ['SLURM_NODEID'])
-    sleep(relative_node_id + 1)
-
-    # init experiment
-    exp = Experiment(
-        name=hyperparams.experiment_name,
-        save_dir=hyperparams.test_tube_save_path,
-        autosave=False,
-        description='test demo'
-    )
-
-    exp.argparse(hparams)
-    exp.save()
-
-    # ------------------------
-    # 3 DEFINE CALLBACKS
-    # ------------------------
-    model_save_path = '{}/{}/{}'.format(hparams.model_save_path, exp.name, exp.version)
-    early_stop = EarlyStopping(
-        monitor='val_acc',
-        patience=3,
-        verbose=True,
-        mode='max'
-    )
-
-    checkpoint = ModelCheckpoint(
-        filepath=model_save_path,
-        save_best_only=True,
-        verbose=True,
-        monitor='val_loss',
-        mode='min'
-    )
-
-    # ------------------------
-    # 4 INIT TRAINER
-    # ------------------------
-    trainer = Trainer(
-        experiment=exp,
-        cluster=cluster,
-        checkpoint_callback=checkpoint,
-        early_stop_callback=early_stop,
-        gpus=hparams.gpus,
-        nb_gpu_nodes=hyperparams.nb_gpu_nodes
-    )
-
-    # ------------------------
-    # 5 START TRAINING
-    # ------------------------
-    trainer.fit(model)
-
-
-def optimize_on_cluster(hyperparams):
-    # enable cluster training
-    # log all scripts to the test tube folder
-    cluster = SlurmCluster(
-        hyperparam_optimizer=hyperparams,
-        log_path=hyperparams.slurm_log_path,
-    )
-
-    # email for cluster coms
-    cluster.notify_job_status(email='add_email_here', on_done=True, on_fail=True)
-
-    # configure cluster
-    cluster.per_experiment_nb_gpus = hyperparams.per_experiment_nb_gpus
-    cluster.per_experiment_nb_nodes = hyperparams.nb_gpu_nodes
-    cluster.job_time = '2:00:00'
-    cluster.gpu_type = 'volta'
-    cluster.memory_mb_per_node = 0
-
-    # any modules for code to run in env
-    cluster.add_command('source activate lightning')
-
-    # run only on 32GB voltas
-    cluster.add_slurm_cmd(cmd='constraint', value='volta32gb', comment='use 32gb gpus')
-    cluster.add_slurm_cmd(cmd='partition', value=hyperparams.gpu_partition, comment='use 32gb gpus')
-
-    # run hopt
-    # creates and submits jobs to slurm
-    cluster.optimize_parallel_cluster_gpu(
-        main,
-        nb_trials=hyperparams.nb_hopt_trials,
-        job_name=hyperparams.experiment_name
-    )
-
-
-if __name__ == '__main__':
-
-    # use default args
-    root_dir = os.path.dirname(os.path.realpath(__file__))
-    demo_log_dir = os.path.join(root_dir, 'pt_lightning_demo_logs')
-
-    checkpoint_dir = os.path.join(demo_log_dir, 'model_weights')
-    test_tube_dir = os.path.join(demo_log_dir, 'test_tube_data')
-    slurm_out_dir = os.path.join(demo_log_dir, 'slurm_scripts')
-
-    parent_parser = HyperOptArgumentParser(strategy='grid_search', add_help=False)
-
-    # cluster args not defined inside the model
-    parent_parser.add_argument('--gpu_partition', type=str, help='consult your cluster manual')
-
-    # TODO: make 1 param
-    parent_parser.add_argument('--per_experiment_nb_gpus', type=int, help='how many gpus to use in a node')
-    parent_parser.add_argument('--gpus', type=str, default='-1', help='how many gpus to use in the node')
-
-    parent_parser.add_argument('--nb_gpu_nodes', type=int, default=1, help='how many nodes to use in a cluster')
-    parent_parser.add_argument('--test_tube_save_path', type=str, default=test_tube_dir, help='where to save logs')
-    parent_parser.add_argument('--slurm_log_path', type=str, default=slurm_out_dir, help='where to save slurm meta')
-    parent_parser.add_argument('--model_save_path', type=str, default=checkpoint_dir, help='where to save model')
-    parent_parser.add_argument('--experiment_name', type=str, default='pt_lightning_exp_a', help='test tube exp name')
-    parent_parser.add_argument('--nb_hopt_trials', type=int, default=1, help='how many grid search trials to run')
-
-    # allow model to overwrite or extend args
-    parser = LightningTemplateModel.add_model_specific_args(parent_parser, root_dir)
-    hyperparams = parser.parse_args()
-
-    # ---------------------
-    # RUN TRAINING
-    # ---------------------
-    # run on HPC cluster
-    print('RUNNING ON SLURM CLUSTER')
-    optimize_on_cluster(hyperparams)

pytorch_lightning/examples/new_project_templates/single_cpu_template.py

@@ -1,110 +0,0 @@
-"""
-Runs a model on a single node across N-gpus.
-"""
-import os
-import sys
-import numpy as np
-from time import sleep
-import torch
-
-from test_tube import HyperOptArgumentParser, Experiment, SlurmCluster
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.utils.arg_parse import add_default_args
-
-from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint
-
-SEED = 2334
-torch.manual_seed(SEED)
-np.random.seed(SEED)
-
-from lightning_module_template import LightningTemplateModel
-
-
-def main(hparams):
-    """
-    Main training routine specific for this project
-    :param hparams:
-    :return:
-    """
-    # ------------------------
-    # 1 INIT LIGHTNING MODEL
-    # ------------------------
-    print('loading model...')
-    model = LightningTemplateModel(hparams)
-    print('model built')
-
-    # ------------------------
-    # 2 INIT TEST TUBE EXP
-    # ------------------------
-
-    # init experiment
-    exp = Experiment(
-        name=hyperparams.experiment_name,
-        save_dir=hyperparams.test_tube_save_path,
-        autosave=False,
-        description='test demo'
-    )
-
-    exp.argparse(hparams)
-    exp.save()
-
-    # ------------------------
-    # 3 DEFINE CALLBACKS
-    # ------------------------
-    model_save_path = '{}/{}/{}'.format(hparams.model_save_path, exp.name, exp.version)
-    early_stop = EarlyStopping(
-        monitor='val_acc',
-        patience=3,
-        verbose=True,
-        mode='max'
-    )
-
-    checkpoint = ModelCheckpoint(
-        filepath=model_save_path,
-        save_best_only=True,
-        verbose=True,
-        monitor='val_loss',
-        mode='min'
-    )
-
-    # ------------------------
-    # 4 INIT TRAINER
-    # ------------------------
-    trainer = Trainer(
-        experiment=exp,
-        checkpoint_callback=checkpoint,
-        early_stop_callback=early_stop,
-    )
-
-    # ------------------------
-    # 5 START TRAINING
-    # ------------------------
-    trainer.fit(model)
-
-
-if __name__ == '__main__':
-
-    # dirs
-    root_dir = os.path.dirname(os.path.realpath(__file__))
-    demo_log_dir = os.path.join(root_dir, 'pt_lightning_demo_logs')
-    checkpoint_dir = os.path.join(demo_log_dir, 'model_weights')
-    test_tube_dir = os.path.join(demo_log_dir, 'test_tube_data')
-
-    # although we user hyperOptParser, we are using it only as argparse right now
-    parent_parser = HyperOptArgumentParser(strategy='grid_search', add_help=False)
-
-    # gpu args
-    parent_parser.add_argument('--test_tube_save_path', type=str, default=test_tube_dir, help='where to save logs')
-    parent_parser.add_argument('--model_save_path', type=str, default=checkpoint_dir, help='where to save model')
-    parent_parser.add_argument('--experiment_name', type=str, default='pt_lightning_exp_a', help='test tube exp name')
-
-    # allow model to overwrite or extend args
-    parser = LightningTemplateModel.add_model_specific_args(parent_parser, root_dir)
-    hyperparams = parser.parse_args()
-
-    # ---------------------
-    # RUN TRAINING
-    # ---------------------
-    # run on HPC cluster
-    print(f'RUNNING ON CPU')
-    main(hyperparams)

pytorch_lightning/examples/new_project_templates/single_gpu_node_16bit_template.py

@@ -1,113 +0,0 @@
-"""
-Runs a model on a single node across N-gpus.
-"""
-import os
-import sys
-import numpy as np
-from time import sleep
-import torch
-
-from test_tube import HyperOptArgumentParser, Experiment, SlurmCluster
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.utils.arg_parse import add_default_args
-
-from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint
-
-SEED = 2334
-torch.manual_seed(SEED)
-np.random.seed(SEED)
-
-from lightning_module_template import LightningTemplateModel
-
-
-def main(hparams):
-    """
-    Main training routine specific for this project
-    :param hparams:
-    :return:
-    """
-    # ------------------------
-    # 1 INIT LIGHTNING MODEL
-    # ------------------------
-    print('loading model...')
-    model = LightningTemplateModel(hparams)
-    print('model built')
-
-    # ------------------------
-    # 2 INIT TEST TUBE EXP
-    # ------------------------
-
-    # init experiment
-    exp = Experiment(
-        name=hyperparams.experiment_name,
-        save_dir=hyperparams.test_tube_save_path,
-        autosave=False,
-        description='test demo'
-    )
-
-    exp.argparse(hparams)
-    exp.save()
-
-    # ------------------------
-    # 3 DEFINE CALLBACKS
-    # ------------------------
-    model_save_path = '{}/{}/{}'.format(hparams.model_save_path, exp.name, exp.version)
-    early_stop = EarlyStopping(
-        monitor='val_acc',
-        patience=3,
-        verbose=True,
-        mode='max'
-    )
-
-    checkpoint = ModelCheckpoint(
-        filepath=model_save_path,
-        save_best_only=True,
-        verbose=True,
-        monitor='val_loss',
-        mode='min'
-    )
-
-    # ------------------------
-    # 4 INIT TRAINER
-    # ------------------------
-    trainer = Trainer(
-        experiment=exp,
-        checkpoint_callback=checkpoint,
-        early_stop_callback=early_stop,
-        gpus=hparams.gpus,
-        use_amp=True
-    )
-
-    # ------------------------
-    # 5 START TRAINING
-    # ------------------------
-    trainer.fit(model)
-
-
-if __name__ == '__main__':
-
-    # dirs
-    root_dir = os.path.dirname(os.path.realpath(__file__))
-    demo_log_dir = os.path.join(root_dir, 'pt_lightning_demo_logs')
-    checkpoint_dir = os.path.join(demo_log_dir, 'model_weights')
-    test_tube_dir = os.path.join(demo_log_dir, 'test_tube_data')
-
-    # although we user hyperOptParser, we are using it only as argparse right now
-    parent_parser = HyperOptArgumentParser(strategy='grid_search', add_help=False)
-
-    # gpu args
-    parent_parser.add_argument('--gpus', type=str, default='-1', help='how many gpus to use in the node. -1 uses all the gpus on the node')
-    parent_parser.add_argument('--test_tube_save_path', type=str, default=test_tube_dir, help='where to save logs')
-    parent_parser.add_argument('--model_save_path', type=str, default=checkpoint_dir, help='where to save model')
-    parent_parser.add_argument('--experiment_name', type=str, default='pt_lightning_exp_a', help='test tube exp name')
-
-    # allow model to overwrite or extend args
-    parser = LightningTemplateModel.add_model_specific_args(parent_parser, root_dir)
-    hyperparams = parser.parse_args()
-
-    # ---------------------
-    # RUN TRAINING
-    # ---------------------
-    # run on HPC cluster
-    print(f'RUNNING INTERACTIVE MODE ON GPUS. gpu ids: {hyperparams.gpus}')
-    main(hyperparams)

pytorch_lightning/examples/new_project_templates/single_gpu_node_dp_template.py

@@ -1,112 +0,0 @@
-"""
-Runs a model on a single node across N-gpus.
-"""
-import os
-import sys
-import numpy as np
-from time import sleep
-import torch
-
-from test_tube import HyperOptArgumentParser, Experiment, SlurmCluster
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.utils.arg_parse import add_default_args
-
-from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint
-
-SEED = 2334
-torch.manual_seed(SEED)
-np.random.seed(SEED)
-
-from lightning_module_template import LightningTemplateModel
-
-
-def main(hparams):
-    """
-    Main training routine specific for this project
-    :param hparams:
-    :return:
-    """
-    # ------------------------
-    # 1 INIT LIGHTNING MODEL
-    # ------------------------
-    print('loading model...')
-    model = LightningTemplateModel(hparams)
-    print('model built')
-
-    # ------------------------
-    # 2 INIT TEST TUBE EXP
-    # ------------------------
-
-    # init experiment
-    exp = Experiment(
-        name=hyperparams.experiment_name,
-        save_dir=hyperparams.test_tube_save_path,
-        autosave=False,
-        description='test demo'
-    )
-
-    exp.argparse(hparams)
-    exp.save()
-
-    # ------------------------
-    # 3 DEFINE CALLBACKS
-    # ------------------------
-    model_save_path = '{}/{}/{}'.format(hparams.model_save_path, exp.name, exp.version)
-    early_stop = EarlyStopping(
-        monitor='val_acc',
-        patience=3,
-        verbose=True,
-        mode='max'
-    )
-
-    checkpoint = ModelCheckpoint(
-        filepath=model_save_path,
-        save_best_only=True,
-        verbose=True,
-        monitor='val_loss',
-        mode='min'
-    )
-
-    # ------------------------
-    # 4 INIT TRAINER
-    # ------------------------
-    trainer = Trainer(
-        experiment=exp,
-        checkpoint_callback=checkpoint,
-        early_stop_callback=early_stop,
-        gpus=hparams.gpus,
-    )
-
-    # ------------------------
-    # 5 START TRAINING
-    # ------------------------
-    trainer.fit(model)
-
-
-if __name__ == '__main__':
-
-    # dirs
-    root_dir = os.path.dirname(os.path.realpath(__file__))
-    demo_log_dir = os.path.join(root_dir, 'pt_lightning_demo_logs')
-    checkpoint_dir = os.path.join(demo_log_dir, 'model_weights')
-    test_tube_dir = os.path.join(demo_log_dir, 'test_tube_data')
-
-    # although we user hyperOptParser, we are using it only as argparse right now
-    parent_parser = HyperOptArgumentParser(strategy='grid_search', add_help=False)
-
-    # gpu args
-    parent_parser.add_argument('--gpus', type=str, default='-1', help='how many gpus to use in the node. -1 uses all the gpus on the node')
-    parent_parser.add_argument('--test_tube_save_path', type=str, default=test_tube_dir, help='where to save logs')
-    parent_parser.add_argument('--model_save_path', type=str, default=checkpoint_dir, help='where to save model')
-    parent_parser.add_argument('--experiment_name', type=str, default='pt_lightning_exp_a', help='test tube exp name')
-
-    # allow model to overwrite or extend args
-    parser = LightningTemplateModel.add_model_specific_args(parent_parser, root_dir)
-    hyperparams = parser.parse_args()
-
-    # ---------------------
-    # RUN TRAINING
-    # ---------------------
-    # run on HPC cluster
-    print(f'RUNNING INTERACTIVE MODE ON GPUS. gpu ids: {hyperparams.gpus}')
-    main(hyperparams)

pytorch_lightning/examples/new_project_templates/single_gpu_node_template.py

@@ -1,112 +0,0 @@
-"""
-Runs a model on a single node across N-gpus.
-"""
-import os
-import sys
-import numpy as np
-from time import sleep
-import torch
-
-from test_tube import HyperOptArgumentParser, Experiment, SlurmCluster
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.utils.arg_parse import add_default_args
-
-from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint
-
-SEED = 2334
-torch.manual_seed(SEED)
-np.random.seed(SEED)
-
-from lightning_module_template import LightningTemplateModel
-
-
-def main(hparams):
-    """
-    Main training routine specific for this project
-    :param hparams:
-    :return:
-    """
-    # ------------------------
-    # 1 INIT LIGHTNING MODEL
-    # ------------------------
-    print('loading model...')
-    model = LightningTemplateModel(hparams)
-    print('model built')
-
-    # ------------------------
-    # 2 INIT TEST TUBE EXP
-    # ------------------------
-
-    # init experiment
-    exp = Experiment(
-        name=hyperparams.experiment_name,
-        save_dir=hyperparams.test_tube_save_path,
-        autosave=False,
-        description='test demo'
-    )
-
-    exp.argparse(hparams)
-    exp.save()
-
-    # ------------------------
-    # 3 DEFINE CALLBACKS
-    # ------------------------
-    model_save_path = '{}/{}/{}'.format(hparams.model_save_path, exp.name, exp.version)
-    early_stop = EarlyStopping(
-        monitor='val_acc',
-        patience=3,
-        verbose=True,
-        mode='max'
-    )
-
-    checkpoint = ModelCheckpoint(
-        filepath=model_save_path,
-        save_best_only=True,
-        verbose=True,
-        monitor='val_loss',
-        mode='min'
-    )
-
-    # ------------------------
-    # 4 INIT TRAINER
-    # ------------------------
-    trainer = Trainer(
-        experiment=exp,
-        checkpoint_callback=checkpoint,
-        early_stop_callback=early_stop,
-        gpus=hparams.gpus,
-    )
-
-    # ------------------------
-    # 5 START TRAINING
-    # ------------------------
-    trainer.fit(model)
-
-
-if __name__ == '__main__':
-
-    # dirs
-    root_dir = os.path.dirname(os.path.realpath(__file__))
-    demo_log_dir = os.path.join(root_dir, 'pt_lightning_demo_logs')
-    checkpoint_dir = os.path.join(demo_log_dir, 'model_weights')
-    test_tube_dir = os.path.join(demo_log_dir, 'test_tube_data')
-
-    # although we user hyperOptParser, we are using it only as argparse right now
-    parent_parser = HyperOptArgumentParser(strategy='grid_search', add_help=False)
-
-    # gpu args
-    parent_parser.add_argument('--gpus', type=str, default='-1', help='how many gpus to use in the node. -1 uses all the gpus on the node')
-    parent_parser.add_argument('--test_tube_save_path', type=str, default=test_tube_dir, help='where to save logs')
-    parent_parser.add_argument('--model_save_path', type=str, default=checkpoint_dir, help='where to save model')
-    parent_parser.add_argument('--experiment_name', type=str, default='pt_lightning_exp_a', help='test tube exp name')
-
-    # allow model to overwrite or extend args
-    parser = LightningTemplateModel.add_model_specific_args(parent_parser, root_dir)
-    hyperparams = parser.parse_args()
-
-    # ---------------------
-    # RUN TRAINING
-    # ---------------------
-    # run on HPC cluster
-    print(f'RUNNING INTERACTIVE MODE ON GPUS. gpu ids: {hyperparams.gpus}')
-    main(hyperparams)

pytorch_lightning/examples/new_project_templates/single_gpu_template.py

@@ -1,112 +0,0 @@
-"""
-Runs a model on a single node across N-gpus.
-"""
-import os
-import sys
-import numpy as np
-from time import sleep
-import torch
-
-from test_tube import HyperOptArgumentParser, Experiment, SlurmCluster
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.utils.arg_parse import add_default_args
-
-from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint
-
-SEED = 2334
-torch.manual_seed(SEED)
-np.random.seed(SEED)
-
-from lightning_module_template import LightningTemplateModel
-
-
-def main(hparams):
-    """
-    Main training routine specific for this project
-    :param hparams:
-    :return:
-    """
-    # ------------------------
-    # 1 INIT LIGHTNING MODEL
-    # ------------------------
-    print('loading model...')
-    model = LightningTemplateModel(hparams)
-    print('model built')
-
-    # ------------------------
-    # 2 INIT TEST TUBE EXP
-    # ------------------------
-
-    # init experiment
-    exp = Experiment(
-        name=hyperparams.experiment_name,
-        save_dir=hyperparams.test_tube_save_path,
-        autosave=False,
-        description='test demo'
-    )
-
-    exp.argparse(hparams)
-    exp.save()
-
-    # ------------------------
-    # 3 DEFINE CALLBACKS
-    # ------------------------
-    model_save_path = '{}/{}/{}'.format(hparams.model_save_path, exp.name, exp.version)
-    early_stop = EarlyStopping(
-        monitor='val_acc',
-        patience=3,
-        verbose=True,
-        mode='max'
-    )
-
-    checkpoint = ModelCheckpoint(
-        filepath=model_save_path,
-        save_best_only=True,
-        verbose=True,
-        monitor='val_loss',
-        mode='min'
-    )
-
-    # ------------------------
-    # 4 INIT TRAINER
-    # ------------------------
-    trainer = Trainer(
-        experiment=exp,
-        checkpoint_callback=checkpoint,
-        early_stop_callback=early_stop,
-        gpus=hparams.gpus,
-    )
-
-    # ------------------------
-    # 5 START TRAINING
-    # ------------------------
-    trainer.fit(model)
-
-
-if __name__ == '__main__':
-
-    # dirs
-    root_dir = os.path.dirname(os.path.realpath(__file__))
-    demo_log_dir = os.path.join(root_dir, 'pt_lightning_demo_logs')
-    checkpoint_dir = os.path.join(demo_log_dir, 'model_weights')
-    test_tube_dir = os.path.join(demo_log_dir, 'test_tube_data')
-
-    # although we user hyperOptParser, we are using it only as argparse right now
-    parent_parser = HyperOptArgumentParser(strategy='grid_search', add_help=False)
-
-    # gpu args
-    parent_parser.add_argument('--gpus', type=str, default='0', help='how many gpus to use in the node. -1 uses all the gpus on the node')
-    parent_parser.add_argument('--test_tube_save_path', type=str, default=test_tube_dir, help='where to save logs')
-    parent_parser.add_argument('--model_save_path', type=str, default=checkpoint_dir, help='where to save model')
-    parent_parser.add_argument('--experiment_name', type=str, default='pt_lightning_exp_a', help='test tube exp name')
-
-    # allow model to overwrite or extend args
-    parser = LightningTemplateModel.add_model_specific_args(parent_parser, root_dir)
-    hyperparams = parser.parse_args()
-
-    # ---------------------
-    # RUN TRAINING
-    # ---------------------
-    # run on HPC cluster
-    print(f'RUNNING INTERACTIVE MODE ON GPUS. gpu ids: {hyperparams.gpus}')
-    main(hyperparams)

pytorch_lightning/examples/new_project_templates/trainer_cpu_template.py

@@ -1,73 +0,0 @@
-import os
-import sys
-
-from test_tube import HyperOptArgumentParser, Experiment
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.utils.arg_parse import add_default_args
-from pytorch_lightning.callbacks.pt_callbacks import EarlyStopping, ModelCheckpoint
-from docs.source.examples.example_model import ExampleModel
-
-
-def main(hparams):
-    """
-    Main training routine specific for this project
-    :param hparams:
-    :return:
-    """
-    # init experiment
-    exp = Experiment(
-        name=hparams.tt_name,
-        debug=hparams.debug,
-        save_dir=hparams.tt_save_path,
-        version=hparams.hpc_exp_number,
-        autosave=False,
-        description=hparams.tt_description
-    )
-
-    exp.argparse(hparams)
-    exp.save()
-
-    # build model
-    model = ExampleModel(hparams)
-
-    # callbacks
-    early_stop = EarlyStopping(
-        monitor='val_acc',
-        patience=3,
-        mode='min',
-        verbose=True,
-    )
-
-    model_save_path = '{}/{}/{}'.format(hparams.model_save_path, exp.name, exp.version)
-    checkpoint = ModelCheckpoint(
-        filepath=model_save_path,
-        save_best_only=True,
-        verbose=True,
-        monitor='val_acc',
-        mode='min'
-    )
-
-    # configure trainer
-    trainer = Trainer(
-        experiment=exp,
-        checkpoint_callback=checkpoint,
-        early_stop_callback=early_stop,
-    )
-
-    # train model
-    trainer.fit(model)
-
-
-if __name__ == '__main__':
-
-    # use default args given by lightning
-    root_dir = os.path.split(os.path.dirname(sys.modules['__main__'].__file__))[0]
-    parent_parser = HyperOptArgumentParser(strategy='random_search', add_help=False)
-    add_default_args(parent_parser, root_dir)
-
-    # allow model to overwrite or extend args
-    parser = ExampleModel.add_model_specific_args(parent_parser)
-    hyperparams = parser.parse_args()
-
-    # train model
-    main(hyperparams)

pytorch_lightning/logging/__init__.py

@@ -0,0 +1,18 @@
+from os import environ
+from .base import LightningLoggerBase, rank_zero_only
+
+try:
+    from .test_tube_logger import TestTubeLogger
+except ImportError:
+    pass
+try:
+    from .mlflow_logger import MLFlowLogger
+except ImportError:
+    pass
+try:
+    # needed to prevent ImportError and duplicated logs.
+    environ["COMET_DISABLE_AUTO_LOGGING"] = "1"
+
+    from .comet_logger import CometLogger
+except ImportError:
+    del environ["COMET_DISABLE_AUTO_LOGGING"]

pytorch_lightning/logging/base.py

@@ -0,0 +1,76 @@
+from functools import wraps
+
+
+def rank_zero_only(fn):
+    """Decorate a logger method to run it only on the process with rank 0
+
+    :param fn: Function to decorate
+    """
+
+    @wraps(fn)
+    def wrapped_fn(self, *args, **kwargs):
+        if self.rank == 0:
+            fn(self, *args, **kwargs)
+
+    return wrapped_fn
+
+
+class LightningLoggerBase(object):
+    """Base class for experiment loggers"""
+
+    def __init__(self):
+        self._rank = 0
+
+    def log_metrics(self, metrics, step_num):
+        """Record metrics
+
+        :param metric: Dictionary with metric names as keys and measured
+        quanties as values
+        :param step_num: Step number at which the metrics should be recorded
+        """
+        raise NotImplementedError()
+
+    def log_hyperparams(self, params):
+        """Record hyperparameters
+
+        :param params: argparse.Namespace containing the hyperparameters
+        """
+        raise NotImplementedError()
+
+    def save(self):
+        """Save log data"""
+        pass
+
+    def finalize(self, status):
+        """Do any processing that is necessary to finalize an experiment
+
+        :param status: Status that the experiment finished with (e.g. success, failed, aborted)
+        """
+        pass
+
+    def close(self):
+        """Do any cleanup that is necessary to close an experiment"""
+        pass
+
+    @property
+    def rank(self):
+        """
+        Process rank. In general, metrics should only be logged by the process
+        with rank 0
+        """
+        return self._rank
+
+    @rank.setter
+    def rank(self, value):
+        """Set the process rank"""
+        self._rank = value
+
+    @property
+    def name(self):
+        """Return the experiment name"""
+        raise NotImplementedError("Sub-classes must provide a name property")
+
+    @property
+    def version(self):
+        """Return the experiment version"""
+        raise NotImplementedError("Sub-classes must provide a version property")

pytorch_lightning/logging/comet_logger.py

@@ -0,0 +1,25 @@
+try:
+    from comet_ml import Experiment as CometExperiment
+except ImportError:
+    raise ImportError('Missing comet_ml package.')
+
+from .base import LightningLoggerBase, rank_zero_only
+
+
+class CometLogger(LightningLoggerBase):
+    def __init__(self, *args, **kwargs):
+        super(CometLogger, self).__init__()
+        self.experiment = CometExperiment(*args, **kwargs)
+
+    @rank_zero_only
+    def log_hyperparams(self, params):
+        self.experiment.log_parameters(vars(params))
+
+    @rank_zero_only
+    def log_metrics(self, metrics, step_num):
+        # self.experiment.set_epoch(self, metrics.get('epoch', 0))
+        self.experiment.log_metrics(metrics)
+
+    @rank_zero_only
+    def finalize(self, status):
+        self.experiment.end()

pytorch_lightning/logging/mlflow_logger.py

@@ -0,0 +1,70 @@
+from logging import getLogger
+from time import time
+
+try:
+    import mlflow
+except ImportError:
+    raise ImportError('Missing mlflow package.')
+
+from .base import LightningLoggerBase, rank_zero_only
+
+logger = getLogger(__name__)
+
+
+class MLFlowLogger(LightningLoggerBase):
+    def __init__(self, experiment_name, tracking_uri=None, tags=None):
+        super().__init__()
+        self.experiment = mlflow.tracking.MlflowClient(tracking_uri)
+        self.experiment_name = experiment_name
+        self._run_id = None
+        self.tags = tags
+
+    @property
+    def run_id(self):
+        if self._run_id is not None:
+            return self._run_id
+
+        experiment = self.experiment.get_experiment_by_name(self.experiment_name)
+        if experiment is None:
+            logger.warning(
+                f"Experiment with name f{self.experiment_name} not found. Creating it."
+            )
+            self.experiment.create_experiment(self.experiment_name)
+            experiment = self.experiment.get_experiment_by_name(self.experiment_name)
+
+        run = self.experiment.create_run(experiment.experiment_id, tags=self.tags)
+        self._run_id = run.info.run_id
+        return self._run_id
+
+    @rank_zero_only
+    def log_hyperparams(self, params):
+        for k, v in vars(params).items():
+            self.experiment.log_param(self.run_id, k, v)
+
+    @rank_zero_only
+    def log_metrics(self, metrics, step_num=None):
+        timestamp_ms = int(time() * 1000)
+        for k, v in metrics.items():
+            if isinstance(v, str):
+                logger.warning(
+                    f"Discarding metric with string value {k}={v}"
+                )
+                continue
+            self.experiment.log_metric(self.run_id, k, v, timestamp_ms, step_num)
+
+    def save(self):
+        pass
+
+    @rank_zero_only
+    def finalize(self, status="FINISHED"):
+        if status == 'success':
+            status = 'FINISHED'
+        self.experiment.set_terminated(self.run_id, status)
+
+    @property
+    def name(self):
+        return self.experiment_name
+
+    @property
+    def version(self):
+        return self._run_id

pytorch_lightning/logging/test_tube_logger.py

@@ -0,0 +1,109 @@
+try:
+    from test_tube import Experiment
+except ImportError:
+    raise ImportError('Missing test-tube package.')
+
+from .base import LightningLoggerBase, rank_zero_only
+
+
+class TestTubeLogger(LightningLoggerBase):
+    __test__ = False
+
+    def __init__(
+            self, save_dir, name="default", description=None, debug=False,
+            version=None, create_git_tag=False
+    ):
+        super().__init__()
+        self.save_dir = save_dir
+        self._name = name
+        self.description = description
+        self.debug = debug
+        self._version = version
+        self.create_git_tag = create_git_tag
+        self._experiment = None
+
+    @property
+    def experiment(self):
+        if self._experiment is not None:
+            return self._experiment
+
+        self._experiment = Experiment(
+            save_dir=self.save_dir,
+            name=self._name,
+            debug=self.debug,
+            version=self.version,
+            description=self.description,
+            create_git_tag=self.create_git_tag,
+            rank=self.rank,
+        )
+        return self._experiment
+
+    @rank_zero_only
+    def log_hyperparams(self, params):
+        # TODO: HACK figure out where this is being set to true
+        self.experiment.debug = self.debug
+        self.experiment.argparse(params)
+
+    @rank_zero_only
+    def log_metrics(self, metrics, step_num=None):
+        # TODO: HACK figure out where this is being set to true
+        self.experiment.debug = self.debug
+        self.experiment.log(metrics, global_step=step_num)
+
+    @rank_zero_only
+    def save(self):
+        # TODO: HACK figure out where this is being set to true
+        self.experiment.debug = self.debug
+        self.experiment.save()
+
+    @rank_zero_only
+    def finalize(self, status):
+        # TODO: HACK figure out where this is being set to true
+        self.experiment.debug = self.debug
+        self.save()
+        self.close()
+
+    @rank_zero_only
+    def close(self):
+        # TODO: HACK figure out where this is being set to true
+        self.experiment.debug = self.debug
+        exp = self.experiment
+        exp.close()
+
+    @property
+    def rank(self):
+        return self._rank
+
+    @rank.setter
+    def rank(self, value):
+        self._rank = value
+        if self._experiment is not None:
+            self.experiment.rank = value
+
+    @property
+    def name(self):
+        if self._experiment is None:
+            return self._name
+        else:
+            return self.experiment.name
+
+    @property
+    def version(self):
+        if self._experiment is None:
+            return self._version
+        else:
+            return self.experiment.version
+
+    # Test tube experiments are not pickleable, so we need to override a few
+    # methods to get DDP working. See
+    # https://docs.python.org/3/library/pickle.html#handling-stateful-objects
+    # for more info.
+    def __getstate__(self):
+        state = self.__dict__.copy()
+        state["_experiment"] = self.experiment.get_meta_copy()
+        return state
+
+    def __setstate__(self, state):
+        self._experiment = state["_experiment"].get_non_ddp_exp()
+        del state["_experiment"]
+        self.__dict__.update(state)

pytorch_lightning/models/__init__.py

@@ -1 +0,0 @@
-from .trainer import Trainer

pytorch_lightning/models/trainer.py

@@ -1,891 +0,0 @@
-"""
-The trainer handles all the logic for running a val loop, training loop, distributing, etc...
-"""
-import subprocess
-import traceback
-import warnings
-import os
-import pdb
-import re
-
-import torch
-from torch.utils.data.distributed import DistributedSampler
-from torch.optim.lr_scheduler import MultiStepLR
-import torch.multiprocessing as mp
-import torch.distributed as dist
-import numpy as np
-import tqdm
-
-from pytorch_lightning.root_module.memory import get_gpu_memory_map
-from pytorch_lightning.root_module.model_saving import TrainerIO
-from pytorch_lightning.pt_overrides.override_data_parallel import LightningDistributedDataParallel, LightningDataParallel
-from pytorch_lightning.utils.debugging import MisconfigurationException
-
-try:
-    from apex import amp
-    APEX_AVAILABLE = True
-except ModuleNotFoundError: # pragma: no cover
-    APEX_AVAILABLE = False
-
-
-def reduce_distributed_output(output, nb_gpus):
-    if nb_gpus <= 1:
-        return output
-
-    # when using DP, we get one output per gpu
-    # average outputs and return
-    if type(output) is torch.Tensor:
-        return output.mean()
-
-    for k, v in output.items():
-        # recurse on nested dics
-        if isinstance(output[k], dict):
-            output[k] = reduce_distributed_output(output[k], nb_gpus)
-
-        # reduce only metrics that have the same nb of gpus
-        elif output[k].size(0) == nb_gpus:
-            reduced = torch.mean(output[k])
-            output[k] = reduced
-    return output
-
-
-class Trainer(TrainerIO):
-
-    def __init__(self,
-                 experiment,
-                 early_stop_callback=None,
-                 checkpoint_callback=None,
-                 gradient_clip=0,
-                 cluster=None,
-                 process_position=0,
-                 current_gpu_name=0,
-                 nb_gpu_nodes=1,
-                 gpus=None,
-                 progress_bar=True,
-                 overfit_pct=0.0,
-                 track_grad_norm=-1,
-                 check_val_every_n_epoch=1,
-                 fast_dev_run=False,
-                 accumulate_grad_batches=1,
-                 max_nb_epochs=1000, min_nb_epochs=1,
-                 train_percent_check=1.0, val_percent_check=1.0, test_percent_check=1.0,
-                 val_check_interval=0.95,
-                 log_save_interval=100, add_log_row_interval=10,
-                 lr_scheduler_milestones=None,
-                 distributed_backend='dp',
-                 use_amp=False,
-                 print_nan_grads=False,
-                 print_weights_summary=True,
-                 amp_level='O2',
-                 nb_sanity_val_steps=5):
-
-        """
-
-        :param experiment: Test-tube experiment
-        :param early_stop_callback: from pytorch_lightning import EarlyStopping
-        :param checkpoint_callback: from pytorch_lightning import Checkpoint
-        :param gradient_clip:
-        :param cluster:
-        :param process_position:
-        :param current_gpu_name:
-        :param nb_gpu_nodes:
-        :param gpus:
-        :param progress_bar:
-        :param overfit_pct:
-        :param track_grad_norm:
-        :param check_val_every_n_epoch:
-        :param fast_dev_run:
-        :param accumulate_grad_batches:
-        :param max_nb_epochs:
-        :param min_nb_epochs:
-        :param train_percent_check:
-        :param val_percent_check:
-        :param test_percent_check:
-        :param val_check_interval:
-        :param log_save_interval:
-        :param add_log_row_interval:
-        :param lr_scheduler_milestones:
-        :param distributed_backend: 'np' to use DistributedParallel, 'ddp' to use DistributedDataParallel
-        :param use_amp:
-        :param print_nan_grads:
-        :param print_weights_summary:
-        :param amp_level:
-        :param nb_sanity_val_steps:
-        """
-
-        # Transfer params
-
-        self.nb_gpu_nodes = nb_gpu_nodes
-        self.gradient_clip = gradient_clip
-        self.check_val_every_n_epoch = check_val_every_n_epoch
-        self.enable_early_stop = early_stop_callback is not None
-        self.track_grad_norm = track_grad_norm
-        self.fast_dev_run = fast_dev_run
-        self.on_gpu = gpus is not None and torch.cuda.is_available()
-        self.progress_bar = progress_bar
-        self.experiment = experiment
-        self.exp_save_path = experiment.get_data_path(experiment.name, experiment.version)
-        self.cluster = cluster
-        self.process_position = process_position
-        self.current_gpu_name = current_gpu_name
-        self.print_weights_summary = print_weights_summary
-        self.checkpoint_callback = checkpoint_callback
-
-        if self.checkpoint_callback is not None:
-            self.checkpoint_callback.save_function = self.save_checkpoint
-
-        self.early_stop = early_stop_callback
-        self.model = None
-        self.max_nb_epochs = max_nb_epochs
-        self.accumulate_grad_batches = accumulate_grad_batches
-        self.early_stop_callback = early_stop_callback
-        self.min_nb_epochs = min_nb_epochs
-        self.nb_sanity_val_steps = nb_sanity_val_steps
-        self.lr_scheduler_milestones = [] if lr_scheduler_milestones is None else [int(x.strip()) for x in lr_scheduler_milestones.split(',')]
-        self.lr_schedulers = []
-        self.amp_level = amp_level
-        self.print_nan_grads = print_nan_grads
-        self.data_parallel_device_ids = None
-        self.world_size = 1
-        self.node_rank = 0
-        self.use_ddp = False
-        self.use_dp = False
-
-        # training bookeeping
-        self.total_batch_nb = 0
-        self.running_loss = []
-        self.avg_loss = 0
-        self.batch_nb = 0
-        self.tqdm_metrics = {}
-        self.nb_val_batches = None
-        self.nb_tng_batches = None
-        self.nb_test_batches = None
-
-        # gpus come in as a string.
-        # if gpus = -1 then use all available devices
-        # otherwise, split the string using commas
-        if gpus is not None:
-            if type(gpus) is list:
-                self.data_parallel_device_ids = gpus
-            elif type(gpus) is str:
-                if gpus == '-1':
-                    self.data_parallel_device_ids = list(range(0, torch.cuda.device_count()))
-                else:
-                    self.data_parallel_device_ids = [int(x.strip()) for x in gpus.split(',')]
-            else:
-                raise Exception('gpus has to be a string or list of ids')
-
-            # set the correct cuda visible devices (using pci order)
-            os.environ["CUDA_DEVICE_ORDER"] = "PCI_BUS_ID"
-            os.environ["CUDA_VISIBLE_DEVICES"] = ','.join([str(x) for x in self.data_parallel_device_ids])
-            print(f'VISIBLE GPUS: {os.environ["CUDA_VISIBLE_DEVICES"]}')
-
-        # make DP and DDP mutually exclusive
-        # single GPU will also use DP with devices=[0]
-        have_gpus = self.data_parallel_device_ids is not None and len(self.data_parallel_device_ids) > 0
-        if have_gpus:
-            self.use_dp = distributed_backend == 'dp'
-            self.use_ddp = distributed_backend == 'ddp'
-
-            # use ddp automatically if nb_gpu_nodes > 1
-            if nb_gpu_nodes > 1 and self.use_dp:  # pragma: no cover
-                self.use_ddp = True
-                self.use_dp = False
-                w = 'DataParallel does not support nb_gpu_nodes > 1. ' \
-                    'Switching to DistributedDataParallel for you. ' \
-                    'To silence this warning set distributed_backend=ddp'
-                warnings.warn(w)
-
-        # extract SLURM flag vars
-        # whenever we have the correct number of tasks, we let slurm manage processes
-        # otherwise we launch the required number of processes
-        if self.use_ddp:
-            self.nb_requested_gpus = len(self.data_parallel_device_ids) * self.nb_gpu_nodes
-            self.nb_slurm_tasks = 0
-            try:
-                self.nb_slurm_tasks = int(os.environ['SLURM_NTASKS'])
-                self.is_slurm_managing_tasks = self.nb_slurm_tasks == self.nb_requested_gpus
-            except Exception as e:
-                # likely not on slurm, so set the slurm managed flag to false
-                self.is_slurm_managing_tasks = False
-
-        # process info
-        self.proc_rank = 0
-
-        # training state
-        self.optimizers = None
-        self.prog_bar = None
-        self.global_step = 0
-        self.current_epoch = 0
-        self.total_batches = 0
-
-        # logging
-        self.log_save_interval = log_save_interval
-        self.val_check_interval = val_check_interval
-        self.add_log_row_interval = add_log_row_interval
-
-        # dataloaders
-        self.tng_dataloader = None
-        self.test_dataloader = None
-        self.val_dataloader = None
-
-        # how much of the data to use
-        self.__determine_data_use_amount(train_percent_check, val_percent_check, test_percent_check, overfit_pct)
-        print('gpu available: {}, used: {}'.format(torch.cuda.is_available(), self.on_gpu))
-
-        # 16 bit mixed precision training using apex
-        self.use_amp = use_amp and APEX_AVAILABLE
-        if self.use_amp:
-            print('using 16bit precision')
-
-        if use_amp and not APEX_AVAILABLE:  # pragma: no cover
-            msg = '''
-            You set use_amp=True but do not have apex installed.
-            Install apex first using this guide and rerun with use_amp=True: 
-            https://github.com/NVIDIA/apex#linux
-            
-            this run will NOT use 16 bit precision
-            '''
-            raise ModuleNotFoundError(msg)
-
-    @property
-    def data_parallel(self):
-        return self.use_dp or self.use_ddp
-
-    def __determine_data_use_amount(self, train_percent_check, val_percent_check, test_percent_check, overfit_pct):
-        """
-        Use less data for debugging purposes
-        """
-        self.train_percent_check = train_percent_check
-        self.val_percent_check = val_percent_check
-        self.test_percent_check = test_percent_check
-        if overfit_pct > 0:
-            self.train_percent_check = overfit_pct
-            self.val_percent_check = overfit_pct
-            self.test_percent_check = overfit_pct
-
-    def __get_model(self):
-        return self.model.module if self.data_parallel else self.model
-
-    def __is_function_implemented(self, f_name):
-        model = self.__get_model()
-        f_op = getattr(model, f_name, None)
-        return callable(f_op)
-
-    @property
-    def __tng_tqdm_dic(self):
-        # ForkedPdb().set_trace()
-        tqdm_dic = {
-            'tng_loss': '{0:.3f}'.format(self.avg_loss),
-            'v_nb': '{}'.format(self.experiment.version),
-            'epoch': '{}'.format(self.current_epoch),
-            'batch_nb':'{}'.format(self.batch_nb),
-        }
-        tqdm_dic.update(self.tqdm_metrics)
-
-        if self.on_gpu:
-            tqdm_dic['gpu'] = '{}'.format(self.current_gpu_name)
-
-        return tqdm_dic
-
-    @property
-    def tng_tqdm_dic(self):
-        """
-        Read-only for tqdm metrics
-        :return:
-        """
-        return self.__tng_tqdm_dic
-
-    def __layout_bookeeping(self):
-
-        # determine number of training batches
-        self.nb_tng_batches = len(self.tng_dataloader)
-        self.nb_tng_batches = int(self.nb_tng_batches * self.train_percent_check)
-
-        # determine number of validation batches
-        self.nb_val_batches = len(self.val_dataloader)
-        self.nb_val_batches = int(self.nb_val_batches * self.val_percent_check)
-        self.nb_val_batches = max(1, self.nb_val_batches)
-        self.nb_val_batches = self.nb_val_batches
-
-        # determine number of test batches
-        self.nb_test_batches = len(self.test_dataloader)
-        self.nb_test_batches = int(self.nb_test_batches * self.test_percent_check)
-
-        # determine when to check validation
-        self.val_check_batch = int(self.nb_tng_batches * self.val_check_interval)
-
-    def __add_tqdm_metrics(self, metrics):
-        for k, v in metrics.items():
-            if type(v) is torch.Tensor:
-                v = v.item()
-
-            self.tqdm_metrics[k] = v
-
-    def validate(self, model, dataloader, max_batches):
-        """
-        Run validation code
-        :param model: PT model
-        :param dataloader: PT dataloader
-        :param max_batches: Scalar
-        :return:
-        """
-        # enable eval mode
-        model.zero_grad()
-        model.eval()
-
-        # disable gradients to save memory
-        torch.set_grad_enabled(False)
-
-        # bookkeeping
-        outputs = []
-
-        # run training
-        for batch_i, data_batch in enumerate(dataloader):
-
-            if data_batch is None:  # pragma: no cover
-                continue
-
-            # stop short when on fast dev run
-            if max_batches is not None and batch_i >= max_batches:
-                break
-
-            # -----------------
-            # RUN VALIDATION STEP
-            # -----------------
-            if self.use_ddp:
-                output = model(data_batch, batch_i)
-            elif self.use_dp:
-                output = model(data_batch, batch_i)
-                output = reduce_distributed_output(output, len(self.data_parallel_device_ids))
-
-            else:
-                output = model.validation_step(data_batch, batch_i)
-
-            outputs.append(output)
-
-            # batch done
-            if self.progress_bar and self.prog_bar is not None:
-                self.prog_bar.update(1)
-
-        # give model a chance to do something with the outputs
-        if self.data_parallel:
-            val_results = model.module.validation_end(outputs)
-        else:
-            val_results = model.validation_end(outputs)
-
-        # enable train mode again
-        model.train()
-
-        # enable gradients to save memory
-        torch.set_grad_enabled(True)
-
-        return val_results
-
-    def get_dataloaders(self, model):
-        """
-        Dataloaders are provided by the model
-        :param model:
-        :return:
-        """
-        self.tng_dataloader = model.tng_dataloader
-        self.test_dataloader = model.test_dataloader
-        self.val_dataloader = model.val_dataloader
-
-        if self.use_ddp and not isinstance(self.tng_dataloader.sampler, DistributedSampler):
-            msg = '''
-            when using multiple gpus and multiple nodes you must pass a DistributedSampler to DataLoader(sampler).
-            
-            ie: this:
-            dataset = myDataset()
-            dataloader = Dataloader(dataset)
-            
-            becomes:
-            dataset = myDataset()
-            dist_sampler = torch.utils.data.distributed.DistributedSampler(dataset)
-            dataloader = Dataloader(dataset, sampler=dist_sampler)
-            '''
-            raise MisconfigurationException(msg)
-
-    # -----------------------------
-    # MODEL TRAINING
-    # -----------------------------
-    def fit(self, model):
-
-        # when using multi-node or DDP within a node start each module in a separate process
-        if self.use_ddp:
-            # must copy only the meta of the exp so it survives pickle/unpickle when going to new process
-            self.experiment = self.experiment.get_meta_copy()
-
-            if self.is_slurm_managing_tasks:
-                task = int(os.environ['SLURM_LOCALID'])
-                self.ddp_train(task, model)
-            else:
-                msg = f"""
-                You requested {self.nb_requested_gpus} GPUs but launched {self.nb_slurm_tasks} slurm tasks. 
-                We will launch {self.nb_requested_gpus} processes for you. 
-                We recommend you let slurm manage the processes by setting: --ntasks-per-node={self.nb_requested_gpus}
-                If you're not using SLURM, ignore this message!
-                """
-                warnings.warn(msg)
-                mp.spawn(self.ddp_train, nprocs=len(self.data_parallel_device_ids), args=(model, ))
-
-        # 1 gpu or dp option triggers training using DP module
-        # easier to avoid NCCL issues
-        elif self.use_dp:
-            self.__dp_train(model)
-
-        # ON CPU
-        else:
-            # run through amp wrapper
-            if self.use_amp:
-                raise MisconfigurationException('amp + cpu is not supported. Please use a GPU option')
-
-            # CHOOSE OPTIMIZER
-            # filter out the weights that were done on gpu so we can load on good old cpus
-            self.optimizers = model.configure_optimizers()
-
-            self.__run_pretrain_routine(model)
-
-        # return 1 when finished
-        # used for testing or when we need to know that training succeeded
-        return 1
-
-    def __dp_train(self, model):
-
-        # CHOOSE OPTIMIZER
-        # filter out the weights that were done on gpu so we can load on good old cpus
-        self.optimizers = model.configure_optimizers()
-
-        model.cuda(self.data_parallel_device_ids[0])
-
-        # check for this bug (amp + dp + !01 doesn't work)
-        # https://github.com/NVIDIA/apex/issues/227
-        if self.use_dp and self.use_amp:
-            m = f'amp level {self.amp_level} with DataParallel is not supported. ' \
-                f'See this note from NVIDIA for more info: https://github.com/NVIDIA/apex/issues/227. ' \
-                f'We recommend you switch to ddp if you want to use amp'
-            raise MisconfigurationException(m)
-
-        model = LightningDataParallel(model, device_ids=self.data_parallel_device_ids)
-
-        self.__run_pretrain_routine(model)
-
-    def ddp_train(self, gpu_nb, model):
-        """
-        Entry point into a DP thread
-        :param gpu_nb:
-        :param model:
-        :param cluster_obj:
-        :return:
-        """
-        # node rank using relative slurm id
-        # otherwise default to node rank 0
-        try:
-            node_id = os.environ['SLURM_NODEID']
-            self.node_rank = int(node_id)
-        except Exception as e:
-            self.node_rank = 0
-
-        # recover original exp before went into process
-        # init in write mode only on proc 0
-        self.experiment.debug = self.proc_rank > 0
-        self.experiment = self.experiment.get_non_ddp_exp()
-
-        # show progbar only on prog_rank 0
-        self.prog_bar = self.prog_bar and self.node_rank == 0 and gpu_nb == 0
-
-        # determine which process we are and world size
-        self.proc_rank = self.node_rank * len(self.data_parallel_device_ids) + gpu_nb
-        self.world_size = self.nb_gpu_nodes * len(self.data_parallel_device_ids)
-
-        # let the exp know the rank to avoid overwriting logs
-        self.experiment.rank = self.proc_rank
-
-        # set up server using proc 0's ip address
-        # try to init for 20 times at max in case ports are taken
-        # where to store ip_table
-        self.__init_tcp_connection()
-
-        # CHOOSE OPTIMIZER
-        # filter out the weights that were done on gpu so we can load on good old cpus
-        self.optimizers = model.configure_optimizers()
-
-        # MODEL
-        # copy model to each gpu
-        torch.cuda.set_device(gpu_nb)
-        model.cuda(gpu_nb)
-
-        # AMP
-        # run through amp wrapper before going to distributed DP
-        if self.use_amp:
-            # An example
-            model, optimizers = amp.initialize(
-                model, self.optimizers, opt_level=self.amp_level,
-            )
-            self.optimizers = optimizers
-
-        model = LightningDistributedDataParallel(model, device_ids=[gpu_nb], find_unused_parameters=True)
-
-        # continue training routine
-        self.__run_pretrain_routine(model)
-
-    def __init_tcp_connection(self):
-        """
-        Connect all procs in the world using the env:// init
-        Use the first node as the root address
-        :param port:
-        :param tries:
-        :return:
-        """
-        # sets the appropriate port
-        try:
-            port = os.environ['MASTER_PORT']
-        except Exception as e:
-            port = 12910
-            os.environ['MASTER_PORT'] = f'{port}'
-
-        # figure out the root node addr
-        try:
-            root_node = os.environ['SLURM_NODELIST'].split(' ')[0]
-        except Exception as e:
-            root_node = '127.0.0.2'
-
-        root_node = self.resolve_root_node_address(root_node)
-        os.environ['MASTER_ADDR'] = root_node
-
-        dist.init_process_group("nccl", rank=self.proc_rank, world_size=self.world_size)
-
-    def resolve_root_node_address(self, root_node):
-        if '[' in root_node:
-            name = root_node.split('[')[0]
-            number = root_node.split(',')[0]
-            if '-' in number:
-                number = number.split('-')[0]
-
-            number = re.sub('[^0-9]', '', number)
-            root_node = name + number
-
-        return root_node
-
-    def __run_pretrain_routine(self, model):
-        """
-        Sanity check a few things before starting actual training
-        :param model:
-        :return:
-        """
-        ref_model = model
-        if self.data_parallel:
-            ref_model = model.module
-
-        ref_model.trainer = self
-
-        # set local properties on the model
-        ref_model.on_gpu = self.on_gpu
-
-        # transfer data loaders from model
-        self.get_dataloaders(ref_model)
-
-        # init training constants
-        self.__layout_bookeeping()
-
-        # add lr schedulers
-        if self.lr_scheduler_milestones is not None:
-            for optimizer in self.optimizers:
-                scheduler = MultiStepLR(optimizer, self.lr_scheduler_milestones)
-                self.lr_schedulers.append(scheduler)
-
-        # print model summary
-        if self.proc_rank == 0 and self.print_weights_summary:
-            ref_model.summarize()
-
-        # give model convenience properties
-        ref_model.trainer = self
-        ref_model.experiment = self.experiment
-
-        # run tiny validation to make sure program won't crash during val
-        _ = self.validate(model, self.val_dataloader, max_batches=self.nb_sanity_val_steps)
-
-        # save exp to get started
-        if self.proc_rank == 0:
-            self.experiment.save()
-
-        # track model now.
-        # if cluster resets state, the model will update with the saved weights
-        self.model = model
-
-        # enable cluster checkpointing
-        # also restores training state
-        if self.cluster is not None:  # pragma: no cover
-            self.enable_auto_hpc_walltime_manager()
-
-        # ---------------------------
-        # CORE TRAINING LOOP
-        # ---------------------------
-        self.__train()
-
-    def __train(self):
-        # run all epochs
-        for epoch_nb in range(self.current_epoch, self.max_nb_epochs):
-            # update the lr scheduler
-            for lr_scheduler in self.lr_schedulers:
-                lr_scheduler.step()
-
-            model = self.__get_model()
-            model.current_epoch = epoch_nb
-
-            # hook
-            if self.__is_function_implemented('on_epoch_start'):
-                model = self.__get_model()
-                model.on_epoch_start()
-
-            self.current_epoch = epoch_nb
-            self.total_batches = self.nb_tng_batches + self.nb_val_batches
-            self.batch_loss_value = 0  # accumulated grads
-
-            # init progbar when requested
-            if self.progress_bar:
-                self.prog_bar = tqdm.tqdm(range(self.total_batches), position=self.process_position)
-
-            for batch_nb, data_batch in enumerate(self.tng_dataloader):
-                self.batch_nb = batch_nb
-                self.global_step += 1
-
-                model = self.__get_model()
-                model.global_step = self.global_step
-
-                # stop when the flag is changed or we've gone past the amount requested in the batches
-                self.total_batch_nb += 1
-                met_batch_limit = batch_nb > self.nb_tng_batches
-                if met_batch_limit:
-                    break
-
-                # ---------------
-                # RUN TRAIN STEP
-                # ---------------
-                batch_result = self.__run_tng_batch(data_batch, batch_nb)
-                early_stop_epoch = batch_result == -1
-
-                # ---------------
-                # RUN VAL STEP
-                # ---------------
-                is_val_check_batch = (batch_nb + 1) % self.val_check_batch == 0
-                if self.fast_dev_run or is_val_check_batch or early_stop_epoch:
-                    self.__run_validation()
-
-                # when batch should be saved
-                if (batch_nb + 1) % self.log_save_interval == 0 or early_stop_epoch:
-                    if self.proc_rank == 0:
-                        self.experiment.save()
-
-                # when metrics should be logged
-                if batch_nb % self.add_log_row_interval == 0 or early_stop_epoch:
-                    # count items in memory
-                    # nb_params, nb_tensors = count_mem_items()
-
-                    model = self.__get_model()
-                    metrics = self.__tng_tqdm_dic
-
-                    # add gpu memory
-                    if self.on_gpu:
-                        mem_map = get_gpu_memory_map()
-                        metrics.update(mem_map)
-
-                    # add norms
-                    if self.track_grad_norm > 0:
-                        model = self.__get_model()
-                        grad_norm_dic = model.grad_norm(self.track_grad_norm)
-                        metrics.update(grad_norm_dic)
-
-                    if self.__is_function_implemented('on_tng_metrics'):
-                        model.on_tng_metrics(metrics)
-
-                    # log metrics
-                    scalar_metrics = self.__metrics_to_scalars(metrics, blacklist=self.__log_vals_blacklist())
-                    if self.proc_rank == 0:
-                        self.experiment.log(scalar_metrics, global_step=self.global_step)
-                        self.experiment.save()
-
-                # hook
-                if self.__is_function_implemented('on_batch_end'):
-                    model = self.__get_model()
-                    model.on_batch_end()
-
-                # end epoch early
-                if early_stop_epoch:
-                    break
-
-            # hook
-            if self.__is_function_implemented('on_epoch_end'):
-                model = self.__get_model()
-                model.on_epoch_end()
-
-            # early stopping
-            met_min_epochs = epoch_nb > self.min_nb_epochs
-            if self.enable_early_stop and met_min_epochs:
-                should_stop = self.early_stop_callback.on_epoch_end(epoch=epoch_nb, logs=self.__tng_tqdm_dic)
-
-                # stop training
-                stop = should_stop and met_min_epochs
-                if stop:
-                    return
-
-    def __metrics_to_scalars(self, metrics, blacklist=[]):
-        new_metrics = {}
-        for k, v in metrics.items():
-            if type(v) is torch.Tensor:
-                v = v.item()
-
-            if type(v) is dict:
-                v = self.__metrics_to_scalars(v)
-
-            if k not in blacklist:
-                new_metrics[k] = float(v)
-
-        return new_metrics
-
-    def __log_vals_blacklist(self):
-        """avoid logging some vals lightning uses to maintain state"""
-        blacklist = {'batch_nb', 'v_nb', 'gpu'}
-        return blacklist
-
-    def __run_tng_batch(self, data_batch, batch_nb):
-        if data_batch is None:
-            return 0
-
-        # hook
-        if self.__is_function_implemented('on_batch_start'):
-            model_ref = self.__get_model()
-            response = model_ref.on_batch_start(data_batch)
-
-            if response == -1:
-                return -1
-
-        if self.progress_bar:
-            self.prog_bar.update(1)
-
-        # forward pass
-        # return a scalar value and a dic with tqdm metrics
-        if self.use_ddp:
-            output = self.model(data_batch, batch_nb)
-        elif self.use_dp:
-            output = self.model(data_batch, batch_nb)
-            output = reduce_distributed_output(output, len(self.data_parallel_device_ids))
-        else:
-            output = self.model.training_step(data_batch, batch_nb)
-
-        try:
-            model_specific_tqdm_metrics_dic = output['tqdm_metrics']
-        except Exception as e:
-            model_specific_tqdm_metrics_dic = {}
-
-        # if output dict doesn't have the keyword loss
-        # then assume the output=loss if scalar
-        try:
-            loss = output['loss']
-        except Exception as e:
-            if type(output) is torch.Tensor:
-                loss = output
-
-        self.__add_tqdm_metrics(model_specific_tqdm_metrics_dic)
-
-        # backward pass
-        if self.use_amp:
-            # scale loss when using amp
-            for optimizer in self.optimizers:
-                with amp.scale_loss(loss, optimizer) as scaled_loss:
-                    scaled_loss.backward()
-        else:
-            loss.backward()
-
-        # insert after step hook
-        if self.__is_function_implemented('on_after_backward'):
-            model_ref = self.__get_model()
-            response = model_ref.on_after_backward()
-
-        if self.print_nan_grads:
-            model = self.__get_model()
-            for param in model.parameters():
-                print(param.grad.float().sum())
-
-        # avoid memory leaks
-        self.batch_loss_value += loss.item()
-
-        # gradient update with accumulated gradients
-        if (self.batch_nb + 1) % self.accumulate_grad_batches == 0:
-
-            # clip gradients
-            if self.gradient_clip > 0:
-                model = self.__get_model()
-                torch.nn.utils.clip_grad_norm(model.parameters(), self.gradient_clip)
-
-            # update gradients across all optimizers
-            for optimizer in self.optimizers:
-                optimizer.step()
-
-                # insert after step hook
-                if self.__is_function_implemented('on_before_zero_grad'):
-                    model_ref = self.__get_model()
-                    response = model_ref.on_before_zero_grad(optimizer)
-
-                # clear gradients
-                optimizer.zero_grad()
-
-            # queuing loss across batches blows it up proportionally... divide out the number accumulated
-            self.batch_loss_value = self.batch_loss_value / self.accumulate_grad_batches
-
-            # track loss
-            self.running_loss.append(self.batch_loss_value)
-            self.batch_loss_value = 0
-            self.avg_loss = np.mean(self.running_loss[-100:])
-
-            # update progbar
-            if self.progress_bar:
-                # add model specific metrics
-                tqdm_metrics = self.__tng_tqdm_dic
-                self.prog_bar.set_postfix(**tqdm_metrics)
-
-        # activate batch end hook
-        if self.__is_function_implemented('on_batch_end'):
-            model = self.__get_model()
-            model.on_batch_end()
-
-        return 0
-
-    def __run_validation(self):
-        # decide if can check epochs
-        can_check_epoch = (self.current_epoch + 1) % self.check_val_every_n_epoch == 0
-        if self.fast_dev_run:
-            print('skipping to check performance bc of --fast_dev_run')
-        elif not can_check_epoch:
-            return
-
-        # hook
-        if self.__is_function_implemented('on_pre_performance_check'):
-            model = self.__get_model()
-            model.on_pre_performance_check()
-
-        # use full val set on end of epoch
-        # use a small portion otherwise
-        max_batches = None if not self.fast_dev_run else 1
-        model_specific_tqdm_metrics_dic = self.validate(
-            self.model,
-            self.val_dataloader,
-            max_batches
-        )
-        self.__add_tqdm_metrics(model_specific_tqdm_metrics_dic)
-
-        # hook
-        if self.__is_function_implemented('on_post_performance_check'):
-            model = self.__get_model()
-            model.on_post_performance_check()
-
-        if self.progress_bar:
-            # add model specific metrics
-            tqdm_metrics = self.__tng_tqdm_dic
-            self.prog_bar.set_postfix(**tqdm_metrics)
-
-        # model checkpointing
-        if self.proc_rank == 0 and self.checkpoint_callback is not None:
-            print('save callback...')
-            self.checkpoint_callback.on_epoch_end(epoch=self.current_epoch, logs=self.__tng_tqdm_dic)

pytorch_lightning/pt_overrides/override_data_parallel.py

@@ -1,12 +1,11 @@
-from torch.nn import DataParallel
-from torch.nn.parallel import DistributedDataParallel
 import itertools
+import threading
 from itertools import chain
 
-import threading
 import torch
 from torch.cuda._utils import _get_device_index
-import pdb
+from torch.nn import DataParallel
+from torch.nn.parallel import DistributedDataParallel
 
 
 def _find_tensors(obj):  # pragma: no cover
@@ -57,6 +56,8 @@ class LightningDataParallel(DataParallel):
             # lightning
             if self.module.training:
                 return self.module.training_step(*inputs[0], **kwargs[0])
+            elif self.module.testing:
+                return self.module.test_step(*inputs[0], **kwargs[0])
             else:
                 return self.module.validation_step(*inputs[0], **kwargs[0])
 
@@ -64,7 +65,6 @@ class LightningDataParallel(DataParallel):
         outputs = self.parallel_apply(replicas, inputs, kwargs)
         return self.gather(outputs, self.output_device)
 
-
     def parallel_apply(self, replicas, inputs, kwargs):
         return parallel_apply(replicas, inputs, kwargs, self.device_ids[:len(replicas)])
 
@@ -87,16 +87,18 @@ class LightningDistributedDataParallel(DistributedDataParallel):
                 # --------------
                 # normal
                 # output = self.module(*inputs[0], **kwargs[0])
-
                 # lightning
                 if self.module.training:
                     output = self.module.training_step(*inputs[0], **kwargs[0])
+                elif self.module.testing:
+                    output = self.module.test_step(*inputs[0], **kwargs[0])
                 else:
                     output = self.module.validation_step(*inputs[0], **kwargs[0])
             else:
                 outputs = self.parallel_apply(self._module_copies[:len(inputs)], inputs, kwargs)
                 output = self.gather(outputs, self.output_device)
         else:
+            # normal
             output = self.module(*inputs, **kwargs)
 
         if torch.is_grad_enabled():
@@ -155,6 +157,10 @@ def parallel_apply(modules, inputs, kwargs_tup=None, devices=None):  # pragma: n
                 # CHANGE
                 if module.training:
                     output = module.training_step(*input, **kwargs)
+
+                elif module.testing:
+                    output = module.test_step(*input, **kwargs)
+
                 else:
                     output = module.validation_step(*input, **kwargs)
                 # ---------------
@@ -165,6 +171,14 @@ def parallel_apply(modules, inputs, kwargs_tup=None, devices=None):  # pragma: n
             with lock:
                 results[i] = e
 
+    # TODO: fix hack (maybe not a hack)
+    # make sure each module knows what training state it's in...
+    # fixes weird bug where copies are out of sync
+    root_m = modules[0]
+    for m in modules[1:]:
+        m.training = root_m.training
+        m.testing = root_m.testing
+
     if len(modules) > 1:
         threads = [threading.Thread(target=_worker,
                                     args=(i, module, input, kwargs, device))

pytorch_lightning/root_module/decorators.py

@@ -1,3 +1,5 @@
+import traceback
+
 
 def data_loader(fn):
     """
@@ -8,10 +10,24 @@ def data_loader(fn):
 
     attr_name = '_lazy_' + fn.__name__
 
-    @property
-    def _data_loader(self):
-        if not hasattr(self, attr_name):
-            setattr(self, attr_name, fn(self))
-        return getattr(self, attr_name)
+    def _get_data_loader(self):
+        try:
+            value = getattr(self, attr_name)
+        except AttributeError:
+            try:
+                value = fn(self)  # Lazy evaluation, done only once.
+                if (
+                        value is not None and
+                        not isinstance(value, list) and
+                        fn.__name__ in ['test_dataloader', 'val_dataloader']
+                ):
+                    value = [value]
+            except AttributeError as e:
+                # Guard against AttributeError suppression. (Issue #142)
+                traceback.print_exc()
+                error = f'{fn.__name__}: An AttributeError was encountered: ' + str(e)
+                raise RuntimeError(error) from e
+            setattr(self, attr_name, value)  # Memoize evaluation.
+        return value
 
-    return _data_loader
+    return _get_data_loader

pytorch_lightning/root_module/grads.py

@@ -1,10 +1,9 @@
-import numpy as np
-from torch import nn
-
 """
 Module to describe gradients
 """
 
+from torch import nn
+
 
 class GradInformation(nn.Module):
 
@@ -18,12 +17,13 @@ class GradInformation(nn.Module):
                     total_norm += param_norm ** norm_type
                     norm = param_norm ** (1 / norm_type)
 
-                    results['grad_{}_norm_{}'.format(norm_type, i)] = round(norm.data.cpu().numpy().flatten()[0], 3)
-                except Exception as e:
+                    grad = round(norm.data.cpu().numpy().flatten()[0], 3)
+                    results['grad_{}_norm_{}'.format(norm_type, i)] = grad
+                except Exception:
                     # this param had no grad
                     pass
 
         total_norm = total_norm ** (1. / norm_type)
-        results['grad_{}_norm_total'.format(norm_type)] = round(total_norm.data.cpu().numpy().flatten()[0], 3)
+        grad = round(total_norm.data.cpu().numpy().flatten()[0], 3)
+        results['grad_{}_norm_total'.format(norm_type)] = grad
         return results
-

pytorch_lightning/root_module/hooks.py

@@ -1,7 +1,24 @@
 import torch
 
+
+try:
+    from apex import amp
+
+    APEX_AVAILABLE = True
+except ImportError:
+    APEX_AVAILABLE = False
+
+
 class ModelHooks(torch.nn.Module):
-    def on_batch_start(self, data_batch):
+
+    def on_sanity_check_start(self):
+        """
+        Called before starting evaluate
+        :return:
+        """
+        pass
+
+    def on_batch_start(self, batch):
         pass
 
     def on_batch_end(self):
@@ -19,9 +36,6 @@ class ModelHooks(torch.nn.Module):
     def on_post_performance_check(self):
         pass
 
-    def on_tng_metrics(self, metrics):
-        pass
-
     def on_before_zero_grad(self, optimizer):
         """
         Called after optimizer.step() and before optimizer.zero_grad()
@@ -43,3 +57,16 @@ class ModelHooks(torch.nn.Module):
         """
         pass
 
+    def backward(self, use_amp, loss, optimizer):
+        """
+        Override backward with your own implementation if you need to
+        :param use_amp: Whether amp was requested or not
+        :param loss: Loss is already scaled by accumulated grads
+        :param optimizer: Current optimizer being used
+        :return:
+        """
+        if use_amp:
+            with amp.scale_loss(loss, optimizer) as scaled_loss:
+                scaled_loss.backward()
+        else:
+            loss.backward()

pytorch_lightning/root_module/memory.py

@@ -1,22 +1,25 @@
-import torch
-import gc
-import subprocess
-import numpy as np
-import pandas as pd
-
-
 '''
 Generates a summary of a model's layers and dimensionality
 '''
 
+import gc
+import os
+import subprocess
+
+import numpy as np
+import pandas as pd
+import torch
+import logging
+
 
 class ModelSummary(object):
 
-    def __init__(self, model):
+    def __init__(self, model, mode='full'):
         '''
         Generates summaries of model layers and dimensions.
         '''
         self.model = model
+        self.mode = mode
         self.in_sizes = []
         self.out_sizes = []
 
@@ -28,9 +31,20 @@ class ModelSummary(object):
     def __repr__(self):
         return self.summary.__str__()
 
+    def named_modules(self):
+        if self.mode == 'full':
+            mods = self.model.named_modules()
+            mods = list(mods)[1:]  # do not include root module (LightningModule)
+        elif self.mode == 'top':
+            # the children are the top-level modules
+            mods = self.model.named_children()
+        else:
+            mods = []
+        return list(mods)
+
     def get_variable_sizes(self):
         '''Run sample input through each layer to get output sizes'''
-        mods = list(self.model.modules())
+        mods = self.named_modules()
         in_sizes = []
         out_sizes = []
         input_ = self.model.example_input_array
@@ -43,8 +57,7 @@ class ModelSummary(object):
 
         with torch.no_grad():
 
-            for i in range(1, len(mods)):
-                m = mods[i]
+            for _, m in mods:
                 if type(input_) is list or type(input_) is tuple:  # pragma: no cover
                     out = m(*input_)
                 else:
@@ -72,16 +85,17 @@ class ModelSummary(object):
 
         self.in_sizes = in_sizes
         self.out_sizes = out_sizes
+        assert len(in_sizes) == len(out_sizes)
         return
 
     def get_layer_names(self):
         '''Collect Layer Names'''
-        mods = list(self.model.named_modules())
+        mods = self.named_modules()
         names = []
         layers = []
-        for m in mods[1:]:
-            names += [m[0]]
-            layers += [str(m[1].__class__)]
+        for name, m in mods:
+            names += [name]
+            layers += [str(m.__class__)]
 
         layer_types = [x.split('.')[-1][:-2] for x in layers]
 
@@ -91,11 +105,9 @@ class ModelSummary(object):
 
     def get_parameter_sizes(self):
         '''Get sizes of all parameters in `model`'''
-        mods = list(self.model.modules())
+        mods = self.named_modules()
         sizes = []
-
-        for i in range(1,len(mods)):
-            m = mods[i]
+        for _, m in mods:
             p = list(m.parameters())
             modsz = []
             for j in range(len(p)):
@@ -127,15 +139,15 @@ class ModelSummary(object):
         if self.model.example_input_array is not None:
             cols.extend(['In_sizes', 'Out_sizes'])
 
-        df = pd.DataFrame(np.zeros( (len(self.layer_names), len(cols))))
+        df = pd.DataFrame(np.zeros((len(self.layer_names), len(cols))))
         df.columns = cols
 
         df['Name'] = self.layer_names
         df['Type'] = self.layer_types
         df['Params'] = self.param_nums
+        df['Params'] = df['Params'].map(get_human_readable_count)
 
         if self.model.example_input_array is not None:
-
             df['In_sizes'] = self.in_sizes
             df['Out_sizes'] = self.out_sizes
 
@@ -152,16 +164,16 @@ class ModelSummary(object):
         self.make_summary()
 
 
-def print_mem_stack(): # pragma: no cover
+def print_mem_stack():  # pragma: no cover
     for obj in gc.get_objects():
         try:
             if torch.is_tensor(obj) or (hasattr(obj, 'data') and torch.is_tensor(obj.data)):
-                print(type(obj), obj.size())
-        except Exception as e:
+                logging.info(type(obj), obj.size())
+        except Exception:
             pass
 
 
-def count_mem_items(): # pragma: no cover
+def count_mem_items():  # pragma: no cover
     nb_params = 0
     nb_tensors = 0
     for obj in gc.get_objects():
@@ -172,12 +184,30 @@ def count_mem_items(): # pragma: no cover
                     nb_params += 1
                 else:
                     nb_tensors += 1
-        except Exception as e:
+        except Exception:
             pass
 
     return nb_params, nb_tensors
 
 
+def get_memory_profile(mode):
+    """
+    'all' means return memory for all gpus
+    'min_max' means return memory for max and min
+    :param mode:
+    :return:
+    """
+    memory_map = get_gpu_memory_map()
+
+    if mode == 'min_max':
+        min_index, min_memory = min(memory_map.items(), key=lambda item: item[1])
+        max_index, max_memory = max(memory_map.items(), key=lambda item: item[1])
+
+        memory_map = {min_index: min_memory, max_index: max_memory}
+
+    return memory_map
+
+
 def get_gpu_memory_map():
     """Get the current gpu usage.
 
@@ -187,15 +217,41 @@ def get_gpu_memory_map():
         Keys are device ids as integers.
         Values are memory usage as integers in MB.
     """
-    result = subprocess.check_output(
+    result = subprocess.run(
         [
-            'nvidia-smi', '--query-gpu=memory.used',
-            '--format=csv,nounits,noheader'
-        ], encoding='utf-8')
+            'nvidia-smi',
+            '--query-gpu=memory.used',
+            '--format=csv,nounits,noheader',
+        ],
+        encoding='utf-8',
+        capture_output=True,
+        check=True)
     # Convert lines into a dictionary
-    gpu_memory = [int(x) for x in result.strip().split('\n')]
-    gpu_memory_map = {}
-    for k, v in zip(range(len(gpu_memory)), gpu_memory):
-        k = f'gpu_{k}'
-        gpu_memory_map[k] = v
+    gpu_memory = [int(x) for x in result.stdout.strip().split(os.linesep)]
+    gpu_memory_map = {f'gpu_{index}': memory for index, memory in enumerate(gpu_memory)}
     return gpu_memory_map
+
+
+def get_human_readable_count(number):
+    """
+    Abbreviates an integer number with K, M, B, T for thousands, millions,
+    billions and trillions, respectively.
+    Examples:
+        123     -> 123
+        1234    -> 1 K       (one thousand)
+        2e6     -> 2 M       (two million)
+        3e9     -> 3 B       (three billion)
+        4e12    -> 4 T       (four trillion)
+        5e15    -> 5,000 T
+    :param number: a positive integer number
+    :returns a string formatted according to the pattern described above.
+    """
+    assert number >= 0
+    labels = [' ', 'K', 'M', 'B', 'T']
+    num_digits = int(np.floor(np.log10(number)) + 1 if number > 0 else 1)
+    num_groups = int(np.ceil(num_digits / 3))
+    num_groups = min(num_groups, len(labels))  # don't abbreviate beyond trillions
+    shift = -3 * (num_groups - 1)
+    number = number * (10 ** shift)
+    index = num_groups - 1
+    return f'{int(number):,d} {labels[index]}'

pytorch_lightning/root_module/model_saving.py

@@ -1,10 +1,3 @@
-import torch
-import os
-import re
-import pdb
-from pytorch_lightning.pt_overrides.override_data_parallel import LightningDistributedDataParallel, LightningDataParallel
-
-
 class ModelIO(object):
 
     def on_load_checkpoint(self, checkpoint):
@@ -39,188 +32,3 @@ class ModelIO(object):
         :return:
         """
         pass
-
-
-class TrainerIO(object):
-
-    def __get_model(self):
-        is_dp_module = type(self.model) is LightningDistributedDataParallel or type(self.model) is LightningDataParallel
-        model = self.model.module if is_dp_module else self.model
-        return model
-
-    # --------------------
-    # MODEL SAVE CHECKPOINT
-    # --------------------
-    def save_checkpoint(self, filepath):
-        checkpoint = self.dump_checkpoint()
-
-        # do the actual save
-        torch.save(checkpoint, filepath)
-
-    def dump_checkpoint(self):
-
-        checkpoint = {
-            'epoch': self.current_epoch,
-            'global_step': self.global_step
-        }
-
-        if self.checkpoint_callback is not None:
-            checkpoint['checkpoint_callback_best'] = self.checkpoint_callback.best
-
-        if self.early_stop_callback is not None:
-            checkpoint['early_stop_callback_wait'] = self.early_stop_callback.wait
-            checkpoint['early_stop_callback_patience'] = self.early_stop_callback.patience
-
-        optimizer_states = []
-        for i, optimizer in enumerate(self.optimizers):
-            optimizer_states.append(optimizer.state_dict())
-
-        checkpoint['optimizer_states'] = optimizer_states
-
-        # add the state_dict from the model
-        model = self.__get_model()
-        checkpoint['state_dict'] = model.state_dict()
-
-        # give the model a chance to add a few things
-        model.on_save_checkpoint(checkpoint)
-
-        return checkpoint
-
-    # --------------------
-    # HPC IO
-    # --------------------
-    def enable_auto_hpc_walltime_manager(self):
-        if self.cluster is None:
-            return
-
-        # allow test tube to handle model check pointing automatically
-        self.cluster.set_checkpoint_save_function(
-            self.hpc_save,
-            kwargs={
-                'folderpath': self.checkpoint_callback.filepath,
-                'experiment': self.experiment
-            }
-        )
-        self.cluster.set_checkpoint_load_function(
-            self.hpc_load,
-            kwargs={
-                'folderpath': self.checkpoint_callback.filepath,
-                'on_gpu': self.on_gpu
-            }
-        )
-
-    def restore_training_state(self, checkpoint):
-        """
-        Restore trainer state.
-        Model will get its change to update
-        :param checkpoint:
-        :return:
-        """
-        if self.checkpoint_callback is not None:
-            self.checkpoint_callback.best = checkpoint['checkpoint_callback_best']
-
-        if self.early_stop_callback is not None:
-            self.early_stop_callback.wait = checkpoint['early_stop_callback_wait']
-            self.early_stop_callback.patience = checkpoint['early_stop_callback_patience']
-
-        self.global_step = checkpoint['global_step']
-        self.current_epoch = checkpoint['epoch']
-
-        # restore the optimizers
-        optimizer_states = checkpoint['optimizer_states']
-        for optimizer, opt_state in zip(self.optimizers, optimizer_states):
-            optimizer.load_state_dict(opt_state)
-
-    # ----------------------------------
-    # PRIVATE OPS
-    # ----------------------------------
-    def hpc_save(self, folderpath, experiment):
-        # make sure the checkpoint folder exists
-        os.makedirs(folderpath, exist_ok=True)
-
-        # save exp to make sure we get all the metrics
-        experiment.save()
-
-        # close experiment to avoid issues
-        experiment.close()
-
-        ckpt_number = self.max_ckpt_in_folder(folderpath) + 1
-
-        if not os.path.exists(folderpath):
-            os.makedirs(folderpath, exist_ok=True)
-        filepath = '{}/hpc_ckpt_{}.ckpt'.format(folderpath, ckpt_number)
-
-        # give model a chance to do something on hpc_save
-        model = self.__get_model()
-        checkpoint = self.dump_checkpoint()
-
-        model.on_hpc_save(checkpoint)
-
-        # do the actual save
-        torch.save(checkpoint, filepath)
-
-        return filepath
-
-    def hpc_load(self, folderpath, on_gpu):
-        filepath = '{}/hpc_ckpt_{}.ckpt'.format(folderpath, self.max_ckpt_in_folder(folderpath))
-
-        if on_gpu:
-            checkpoint = torch.load(filepath)
-        else:
-            checkpoint = torch.load(filepath, map_location=lambda storage, loc: storage)
-
-        # load training state (affects trainer only)
-        self.restore_training_state(checkpoint)
-
-        # load model state
-        model = self.__get_model()
-
-        # load the state_dict on the model automatically
-        model.load_state_dict(checkpoint['state_dict'])
-
-        # call model hook
-        model.on_hpc_load(checkpoint)
-
-    def max_ckpt_in_folder(self, path):
-        files = os.listdir(path)
-        files = [x for x in files if 'ckpt_' in x]
-        if len(files) == 0:
-            return 0
-
-        ckpt_vs = []
-        for name in files:
-            name = name.split('ckpt_')[-1]
-            name = re.sub('[^0-9]', '', name)
-            ckpt_vs.append(int(name))
-
-        return max(ckpt_vs)
-
-
-def load_hparams_from_tags_csv(tags_csv):
-    from argparse import Namespace
-    import pandas as pd
-
-    tags_df = pd.read_csv(tags_csv)
-    dic = tags_df.to_dict(orient='records')
-
-    ns_dict = {row['key']: convert(row['value']) for row in dic}
-
-    ns = Namespace(**ns_dict)
-    return ns
-
-
-def convert(val):
-    constructors = [int, float, str]
-
-    if type(val) is str:
-        if val.lower() == 'true':
-            return True
-        if val.lower() == 'false':
-            return False
-
-    for c in constructors:
-        try:
-            return c(val)
-        except ValueError:
-            pass
-    return val

pytorch_lightning/root_module/root_module.py

@@ -1,9 +1,19 @@
+import os
+import warnings
+import collections
+from argparse import Namespace
+
 import torch
-from pytorch_lightning.root_module.memory import ModelSummary
-from pytorch_lightning.root_module.grads import GradInformation
-from pytorch_lightning.root_module.model_saving import ModelIO, load_hparams_from_tags_csv
-from pytorch_lightning.root_module.hooks import ModelHooks
+import torch.distributed as dist
+
 from pytorch_lightning.root_module.decorators import data_loader
+from pytorch_lightning.root_module.grads import GradInformation
+from pytorch_lightning.root_module.hooks import ModelHooks
+from pytorch_lightning.root_module.memory import ModelSummary
+from pytorch_lightning.root_module.model_saving import ModelIO
+from pytorch_lightning.trainer.trainer_io import load_hparams_from_tags_csv
+import logging
+from pytorch_lightning.pt_overrides.override_data_parallel import LightningDistributedDataParallel
 
 
 class LightningModule(GradInformation, ModelIO, ModelHooks):
@@ -17,11 +27,15 @@ class LightningModule(GradInformation, ModelIO, ModelHooks):
         self.global_step = 0
         self.loaded_optimizer_states_dict = {}
         self.trainer = None
-        self.experiment = None
+        self.logger = None
         self.example_input_array = None
 
         # track if gpu was requested for checkpointing
         self.on_gpu = False
+        self.use_dp = False
+        self.use_ddp = False
+        self.use_ddp2 = False
+        self.use_amp = False
 
     def forward(self, *args, **kwargs):
         """
@@ -32,81 +46,237 @@ class LightningModule(GradInformation, ModelIO, ModelHooks):
         """
         raise NotImplementedError
 
-    def validation_step(self, data_batch, batch_nb):
+    def training_step(self, *args, **kwargs):
         """
-        return whatever outputs will need to be aggregated in validation_end
-        :param data_batch:
-        :return:
+        return loss, dict with metrics for tqdm
+        :param called with batch, batch_nb
+        additional: optimizer_i if multiple optimizers used
+        :return: dict with loss key and optional log, progress keys
+                if implementing training_step, return whatever you need in that step
         """
         raise NotImplementedError
 
+    def training_end(self, *args, **kwargs):
+        """
+        return loss, dict with metrics for tqdm
+        :param called with outputs of training_step
+        :return: dict with loss key and optional log, progress keys
+        """
+        pass
+
+    def validation_step(self, *args, **kwargs):
+        """
+        return whatever outputs will need to be aggregated in validation_end
+        OPTIONAL
+        :param called with batch, batch_nb
+        additional: dataset_i if multiple val datasets used
+        :return:
+        """
+        pass
+
+    def test_step(self, *args, **kwargs):
+        """
+        return whatever outputs will need to be aggregated in test_end
+        OPTIONAL
+        :param called with batch, batch_nb
+        additional: dataset_i if multiple val datasets used
+        :return:
+        """
+        pass
+
     def validation_end(self, outputs):
         """
         Outputs has the appended output after each validation step
+        OPTIONAL
         :param outputs:
         :return: dic_with_metrics for tqdm
         """
-        raise NotImplementedError
+        pass
 
-    def training_step(self, data_batch, batch_nb):
+    def test_end(self, outputs):
         """
-        return loss, dict with metrics for tqdm
-        :param data_batch:
-        :return:
+        Outputs has the appended output after each test step
+        OPTIONAL
+        :param outputs:
+        :return: dic_with_metrics for tqdm
         """
-        raise NotImplementedError
+        pass
+
+    def configure_ddp(self, model, device_ids):
+        """
+        Override to init DDP in a different way or use your own wrapper.
+        Must return model.
+        :param model:
+        :param device_ids:
+        :return: DDP wrapped model
+        """
+        model = LightningDistributedDataParallel(
+            model,
+            device_ids=device_ids,
+            find_unused_parameters=True
+        )
+        return model
+
+    def init_ddp_connection(self, proc_rank, world_size):
+        """
+        Connect all procs in the world using the env:// init
+        Use the first node as the root address
+        """
+
+        # use slurm job id for the port number
+        # guarantees unique ports across jobs from same grid search
+        try:
+            # use the last 4 numbers in the job id as the id
+            default_port = os.environ['SLURM_JOB_ID']
+            default_port = default_port[-4:]
+
+            # all ports should be in the 10k+ range
+            default_port = int(default_port) + 15000
+
+        except Exception as e:
+            default_port = 12910
+
+        # if user gave a port number, use that one instead
+        try:
+            default_port = os.environ['MASTER_PORT']
+        except Exception:
+            os.environ['MASTER_PORT'] = str(default_port)
+
+        # figure out the root node addr
+        try:
+            root_node = os.environ['SLURM_NODELIST'].split(' ')[0]
+        except Exception:
+            root_node = '127.0.0.2'
+
+        root_node = self.trainer.resolve_root_node_address(root_node)
+        os.environ['MASTER_ADDR'] = root_node
+        dist.init_process_group('nccl', rank=proc_rank, world_size=world_size)
+
+    def configure_apex(self, amp, model, optimizers, amp_level):
+        """
+        Override to init AMP your own way
+        Must return a model and list of optimizers
+        :param amp:
+        :param model:
+        :param optimizers:
+        :param amp_level:
+        :return: Apex wrapped model and optimizers
+        """
+        model, optimizers = amp.initialize(
+            model, optimizers, opt_level=amp_level,
+        )
+
+        return model, optimizers
 
     def configure_optimizers(self):
         """
-        Return array of optimizers
+        Return a list of optimizers and a list of schedulers (could be empty)
         :return:
         """
         raise NotImplementedError
 
+    def optimizer_step(self, epoch_nb, batch_nb, optimizer, optimizer_i, second_order_closure=None):
+        """
+        Do something instead of the standard optimizer behavior
+        :param epoch_nb:
+        :param batch_nb:
+        :param optimizer:
+        :param optimizer_i:
+        :param second_order_closure: closure for second order methods
+        :return:
+        """
+        if isinstance(optimizer, torch.optim.LBFGS):
+            optimizer.step(second_order_closure)
+        else:
+            optimizer.step()
+
+        # clear gradients
+        optimizer.zero_grad()
+
+    def tbptt_split_batch(self, batch, split_size):
+        """
+        Return list of batch splits. Each split will be passed to forward_step to enable truncated
+        back propagation through time. The default implementation splits root level Tensors and
+        Sequences at dim=1 (i.e. time dim). It assumes that each time dim is the same length.
+        :return:
+        """
+        time_dims = [len(x[0]) for x in batch if isinstance(
+            x, torch.Tensor) or isinstance(x, collections.Sequence)]
+        assert len(time_dims) >= 1, "Unable to determine batch time dimension"
+        assert all(x == time_dims[0] for x in time_dims), "Batch time dimension length is ambiguous"
+
+        splits = []
+        for t in range(0, time_dims[0], split_size):
+            batch_split = []
+            for i, x in enumerate(batch):
+                if isinstance(x, torch.Tensor):
+                    split_x = x[:, t:t + split_size]
+                elif isinstance(x, collections.Sequence):
+                    split_x = [None] * len(x)
+                    for batch_idx in range(len(x)):
+                        split_x[batch_idx] = x[batch_idx][t:t + split_size]
+
+                batch_split.append(split_x)
+
+            splits.append(batch_split)
+
+        return splits
+
     @data_loader
     def tng_dataloader(self):
         """
-        Implement a function to load an h5py of this data
+        Implement a PyTorch DataLoader
+        * Deprecated in v0.5.0. use train_dataloader instead. *
         :return:
         """
         raise NotImplementedError
 
+    @data_loader
+    def train_dataloader(self):
+        """
+        Implement a PyTorch DataLoader
+        :return:
+        """
+        #
+        try:
+            output = self.tng_dataloader()
+            warnings.warn("tng_dataloader has been renamed to train_dataloader since v0.5.0",
+                          DeprecationWarning)
+            return output
+        except NotImplementedError:
+            raise NotImplementedError
+
     @data_loader
     def test_dataloader(self):
         """
-        Implement a function to load an h5py of this data
+        Implement a PyTorch DataLoader
         :return:
         """
-        raise NotImplementedError
+        return None
 
     @data_loader
     def val_dataloader(self):
         """
-        Implement a function to load an h5py of this data
+        Implement a PyTorch DataLoader
         :return:
         """
-        raise NotImplementedError
+        return None
 
     @classmethod
-    def load_from_metrics(cls, weights_path, tags_csv, on_gpu, map_location=None):
+    def load_from_metrics(cls, weights_path, tags_csv):
         """
         Primary way of loading model from csv weights path
         :param weights_path:
         :param tags_csv:
-        :param on_gpu:
         :param map_location: dic for mapping storage {'cuda:1':'cuda:0'}
         :return:
         """
         hparams = load_hparams_from_tags_csv(tags_csv)
-        hparams.__setattr__('on_gpu', on_gpu)
+        hparams.__setattr__('on_gpu', False)
 
-        if on_gpu:
-            if map_location is not None:
-                checkpoint = torch.load(weights_path, map_location=map_location)
-            else:
-                checkpoint = torch.load(weights_path)
-        else:
-            checkpoint = torch.load(weights_path, map_location=lambda storage, loc: storage)
+        # load on CPU only to avoid OOM issues
+        # then its up to user to put back on GPUs
+        checkpoint = torch.load(weights_path, map_location=lambda storage, loc: storage)
 
         # load the state_dict on the model automatically
         model = cls(hparams)
@@ -117,17 +287,48 @@ class LightningModule(GradInformation, ModelIO, ModelHooks):
 
         return model
 
-    def summarize(self):
-        model_summary = ModelSummary(self)
-        print(model_summary)
+    @classmethod
+    def load_from_checkpoint(cls, checkpoint_path):
+        """
+        Primary way of loading model from a checkpoint
+        :param checkpoint_path:
+        :param map_location: dic for mapping storage {'cuda:1':'cuda:0'}
+        :return:
+        """
+
+        # load on CPU only to avoid OOM issues
+        # then its up to user to put back on GPUs
+        checkpoint = torch.load(checkpoint_path, map_location=lambda storage, loc: storage)
+        try:
+            ckpt_hparams = checkpoint['hparams']
+        except KeyError:
+            raise IOError(
+                "Checkpoint does not contain hyperparameters. Are your model hyperparameters stored"
+                "in self.hparams?"
+            )
+        hparams = Namespace(**ckpt_hparams)
+
+        # load the state_dict on the model automatically
+        model = cls(hparams)
+        model.load_state_dict(checkpoint['state_dict'])
+
+        # give model a chance to load something
+        model.on_load_checkpoint(checkpoint)
+
+        return model
+
+    def summarize(self, mode):
+        model_summary = ModelSummary(self, mode=mode)
+        logging.info(model_summary)
 
     def freeze(self):
         for param in self.parameters():
             param.requires_grad = False
 
+        self.eval()
+
     def unfreeze(self):
         for param in self.parameters():
             param.requires_grad = True
 
-
-
+        self.train()

pytorch_lightning/testing/__init__.py

@@ -0,0 +1,12 @@
+from .lm_test_module import LightningTestModel
+from .lm_test_module_base import LightningTestModelBase
+from .lm_test_module_mixins import (
+    LightningValidationStepMixin,
+    LightningValidationMixin,
+    LightningValidationStepMultipleDataloadersMixin,
+    LightningValidationMultipleDataloadersMixin,
+    LightningTestStepMixin,
+    LightningTestMixin,
+    LightningTestStepMultipleDataloadersMixin,
+    LightningTestMultipleDataloadersMixin,
+)

pytorch_lightning/testing/lm_test_module.py

@@ -0,0 +1,13 @@
+import torch
+
+from .lm_test_module_base import LightningTestModelBase
+from .lm_test_module_mixins import LightningValidationMixin, LightningTestMixin
+
+
+class LightningTestModel(LightningValidationMixin, LightningTestMixin, LightningTestModelBase):
+    """
+    Most common test case. Validation and test dataloaders
+    """
+
+    def on_training_metrics(self, logs):
+        logs['some_tensor_to_test'] = torch.rand(1)

pytorch_lightning/testing/lm_test_module_base.py

@@ -1,22 +1,28 @@
 import os
 from collections import OrderedDict
-import torch.nn as nn
-from torchvision.datasets import MNIST
-import torchvision.transforms as transforms
+
 import torch
+import torch.nn as nn
 import torch.nn.functional as F
-from test_tube import HyperOptArgumentParser
 from torch import optim
 from torch.utils.data import DataLoader
 from torch.utils.data.distributed import DistributedSampler
+from torchvision import transforms
+from torchvision.datasets import MNIST
+try:
+    from test_tube import HyperOptArgumentParser
+except ImportError:
+    # TODO: this should be discussed and moved out of this package
+    raise ImportError('Missing test-tube package.')
 
+from pytorch_lightning import data_loader
 from pytorch_lightning.root_module.root_module import LightningModule
-import pytorch_lightning as ptl
 
 
-class LightningTestModel(LightningModule):
+class LightningTestModelBase(LightningModule):
     """
-    Sample model to show how to define a template
+    Base LightningModule for testing. Implements only the required
+    interface
     """
 
     def __init__(self, hparams, force_remove_distributed_sampler=False):
@@ -25,7 +31,7 @@ class LightningTestModel(LightningModule):
         :param hparams:
         """
         # init superclass
-        super(LightningTestModel, self).__init__()
+        super(LightningTestModelBase, self).__init__()
         self.hparams = hparams
 
         self.batch_size = hparams.batch_size
@@ -47,11 +53,13 @@ class LightningTestModel(LightningModule):
         Layout model
         :return:
         """
-        self.c_d1 = nn.Linear(in_features=self.hparams.in_features, out_features=self.hparams.hidden_dim)
+        self.c_d1 = nn.Linear(in_features=self.hparams.in_features,
+                              out_features=self.hparams.hidden_dim)
         self.c_d1_bn = nn.BatchNorm1d(self.hparams.hidden_dim)
         self.c_d1_drop = nn.Dropout(self.hparams.drop_prob)
 
-        self.c_d2 = nn.Linear(in_features=self.hparams.hidden_dim, out_features=self.hparams.out_features)
+        self.c_d2 = nn.Linear(in_features=self.hparams.hidden_dim,
+                              out_features=self.hparams.out_features)
 
     # ---------------------
     # TRAINING
@@ -77,14 +85,14 @@ class LightningTestModel(LightningModule):
         nll = F.nll_loss(logits, labels)
         return nll
 
-    def training_step(self, data_batch, batch_i):
+    def training_step(self, batch, batch_idx):
         """
         Lightning calls this inside the training loop
-        :param data_batch:
+        :param batch:
         :return:
         """
         # forward pass
-        x, y = data_batch
+        x, y = batch
         x = x.view(x.size(0), -1)
 
         y_hat = self.forward(x)
@@ -96,106 +104,51 @@ class LightningTestModel(LightningModule):
         if self.trainer.use_dp:
             loss_val = loss_val.unsqueeze(0)
 
-        output = OrderedDict({
-            'loss': loss_val
-        })
-
-        # can also return just a scalar instead of a dict (return loss_val)
-        return output
-
-    def validation_step(self, data_batch, batch_i):
-        """
-        Lightning calls this inside the validation loop
-        :param data_batch:
-        :return:
-        """
-        x, y = data_batch
-        x = x.view(x.size(0), -1)
-        y_hat = self.forward(x)
-
-        loss_val = self.loss(y, y_hat)
-
-        # acc
-        labels_hat = torch.argmax(y_hat, dim=1)
-        val_acc = torch.sum(y == labels_hat).item() / (len(y) * 1.0)
-        val_acc = torch.tensor(val_acc)
-
-        if self.on_gpu:
-            val_acc = val_acc.cuda(loss_val.device.index)
-
-        # in DP mode (default) make sure if result is scalar, there's another dim in the beginning
-        if self.trainer.use_dp:
-            loss_val = loss_val.unsqueeze(0)
-            val_acc = val_acc.unsqueeze(0)
-
         # alternate possible outputs to test
         if self.trainer.batch_nb % 1 == 0:
             output = OrderedDict({
-                'val_loss': loss_val,
-                'val_acc': val_acc,
+                'loss': loss_val,
+                'progress_bar': {'some_val': loss_val * loss_val},
+                'log': {'train_some_val': loss_val * loss_val},
             })
+
             return output
         if self.trainer.batch_nb % 2 == 0:
-            return val_acc
-
-        if self.trainer.batch_nb % 3 == 0:
-            output = OrderedDict({
-                'val_loss': loss_val,
-                'val_acc': val_acc,
-                'test_dic': {'val_loss_a': loss_val}
-            })
-            return output
-
-    def validation_end(self, outputs):
-        """
-        Called at the end of validation to aggregate outputs
-        :param outputs: list of individual outputs of each validation step
-        :return:
-        """
-        # if returned a scalar from validation_step, outputs is a list of tensor scalars
-        # we return just the average in this case (if we want)
-        # return torch.stack(outputs).mean()
-
-        val_loss_mean = 0
-        val_acc_mean = 0
-        for output in outputs:
-            val_loss_mean += output['val_loss']
-            val_acc_mean += output['val_acc']
-
-        val_loss_mean /= len(outputs)
-        val_acc_mean /= len(outputs)
-
-        tqdm_dic = {'val_loss': val_loss_mean.item(), 'val_acc': val_acc_mean.item()}
-        return tqdm_dic
-
-    def on_tng_metrics(self, logs):
-        logs['some_tensor_to_test'] = torch.rand(1)
+            return loss_val
 
     # ---------------------
     # TRAINING SETUP
     # ---------------------
     def configure_optimizers(self):
         """
-        return whatever optimizers we want here
+        return whatever optimizers we want here.
         :return: list of optimizers
         """
-        optimizer = optim.Adam(self.parameters(), lr=self.hparams.learning_rate)
-        return [optimizer]
+        # try no scheduler for this model (testing purposes)
+        if self.hparams.optimizer_name == 'lbfgs':
+            optimizer = optim.LBFGS(self.parameters(), lr=self.hparams.learning_rate)
+        else:
+            optimizer = optim.Adam(self.parameters(), lr=self.hparams.learning_rate)
 
-    def __dataloader(self, train):
+        # test returning only 1 list instead of 2
+        return optimizer
+
+    def _dataloader(self, train):
         # init data generators
-        transform = transforms.Compose([transforms.ToTensor(), transforms.Normalize((0.5,), (1.0,))])
-        dataset = MNIST(root=self.hparams.data_root, train=train, transform=transform, download=True)
+        transform = transforms.Compose([transforms.ToTensor(),
+                                        transforms.Normalize((0.5,), (1.0,))])
+        dataset = MNIST(root=self.hparams.data_root, train=train,
+                        transform=transform, download=True)
 
         # when using multi-node we need to add the datasampler
         train_sampler = None
         batch_size = self.hparams.batch_size
 
         try:
-            if self.on_gpu and not self.force_remove_distributed_sampler:
+            if self.use_ddp and not self.force_remove_distributed_sampler:
                 train_sampler = DistributedSampler(dataset, rank=self.trainer.proc_rank)
                 batch_size = batch_size // self.trainer.world_size  # scale batch size
-        except Exception as e:
+        except Exception:
             pass
 
         should_shuffle = train_sampler is None
@@ -208,20 +161,12 @@ class LightningTestModel(LightningModule):
 
         return loader
 
-    @ptl.data_loader
-    def tng_dataloader(self):
-        return self.__dataloader(train=True)
-
-    @ptl.data_loader
-    def val_dataloader(self):
-        return self.__dataloader(train=False)
-
-    @ptl.data_loader
-    def test_dataloader(self):
-        return self.__dataloader(train=False)
+    @data_loader
+    def train_dataloader(self):
+        return self._dataloader(train=True)
 
     @staticmethod
-    def add_model_specific_args(parent_parser, root_dir):
+    def add_model_specific_args(parent_parser, root_dir):  # pragma: no cover
         """
         Parameters you define here will be available to your model through self.hparams
         :param parent_parser:
@@ -231,23 +176,28 @@ class LightningTestModel(LightningModule):
         parser = HyperOptArgumentParser(strategy=parent_parser.strategy, parents=[parent_parser])
 
         # param overwrites
-        # parser.set_defaults(gradient_clip=5.0)
+        # parser.set_defaults(gradient_clip_val=5.0)
 
         # network params
         parser.opt_list('--drop_prob', default=0.2, options=[0.2, 0.5], type=float, tunable=False)
-        parser.add_argument('--in_features', default=28*28, type=int)
+        parser.add_argument('--in_features', default=28 * 28, type=int)
         parser.add_argument('--out_features', default=10, type=int)
-        parser.add_argument('--hidden_dim', default=50000, type=int) # use 500 for CPU, 50000 for GPU to see speed difference
+        # use 500 for CPU, 50000 for GPU to see speed difference
+        parser.add_argument('--hidden_dim', default=50000, type=int)
 
         # data
         parser.add_argument('--data_root', default=os.path.join(root_dir, 'mnist'), type=str)
 
         # training params (opt)
-        parser.opt_list('--learning_rate', default=0.001*8, type=float, options=[0.0001, 0.0005, 0.001, 0.005],
+        parser.opt_list('--learning_rate', default=0.001 * 8, type=float,
+                        options=[0.0001, 0.0005, 0.001, 0.005],
                         tunable=False)
-        parser.opt_list('--optimizer_name', default='adam', type=str, options=['adam'], tunable=False)
+        parser.opt_list('--optimizer_name', default='adam', type=str,
+                        options=['adam'], tunable=False)
 
-        # if using 2 nodes with 4 gpus each the batch size here (256) will be 256 / (2*8) = 16 per gpu
-        parser.opt_list('--batch_size', default=256*8, type=int, options=[32, 64, 128, 256], tunable=False,
-                        help='batch size will be divided over all the gpus being used across all nodes')
+        # if using 2 nodes with 4 gpus each the batch size here
+        #  (256) will be 256 / (2*8) = 16 per gpu
+        parser.opt_list('--batch_size', default=256 * 8, type=int,
+                        options=[32, 64, 128, 256], tunable=False,
+                        help='batch size will be divided over all gpus being used across all nodes')
         return parser

pytorch_lightning/testing/lm_test_module_mixins.py

@@ -0,0 +1,381 @@
+from collections import OrderedDict
+
+import torch
+
+from pytorch_lightning import data_loader
+
+
+class LightningValidationStepMixin:
+    """
+    Add val_dataloader and validation_step methods for the case
+    when val_dataloader returns a single dataloader
+    """
+
+    @data_loader
+    def val_dataloader(self):
+        return self._dataloader(train=False)
+
+    def validation_step(self, batch, batch_idx):
+        """
+        Lightning calls this inside the validation loop
+        :param batch:
+        :return:
+        """
+        x, y = batch
+        x = x.view(x.size(0), -1)
+        y_hat = self.forward(x)
+
+        loss_val = self.loss(y, y_hat)
+
+        # acc
+        labels_hat = torch.argmax(y_hat, dim=1)
+        val_acc = torch.sum(y == labels_hat).item() / (len(y) * 1.0)
+        val_acc = torch.tensor(val_acc)
+
+        if self.on_gpu:
+            val_acc = val_acc.cuda(loss_val.device.index)
+
+        # in DP mode (default) make sure if result is scalar, there's another dim in the beginning
+        if self.trainer.use_dp:
+            loss_val = loss_val.unsqueeze(0)
+            val_acc = val_acc.unsqueeze(0)
+
+        # alternate possible outputs to test
+        if batch_idx % 1 == 0:
+            output = OrderedDict({
+                'val_loss': loss_val,
+                'val_acc': val_acc,
+            })
+            return output
+        if batch_idx % 2 == 0:
+            return val_acc
+
+        if batch_idx % 3 == 0:
+            output = OrderedDict({
+                'val_loss': loss_val,
+                'val_acc': val_acc,
+                'test_dic': {'val_loss_a': loss_val}
+            })
+            return output
+
+
+class LightningValidationMixin(LightningValidationStepMixin):
+    """
+    Add val_dataloader, validation_step, and validation_end methods for the case
+    when val_dataloader returns a single dataloader
+    """
+
+    def validation_end(self, outputs):
+        """
+        Called at the end of validation to aggregate outputs
+        :param outputs: list of individual outputs of each validation step
+        :return:
+        """
+        # if returned a scalar from validation_step, outputs is a list of tensor scalars
+        # we return just the average in this case (if we want)
+        # return torch.stack(outputs).mean()
+        val_loss_mean = 0
+        val_acc_mean = 0
+        for output in outputs:
+            val_loss = output['val_loss']
+
+            # reduce manually when using dp
+            if self.trainer.use_dp or self.trainer.use_ddp2:
+                val_loss = torch.mean(val_loss)
+            val_loss_mean += val_loss
+
+            # reduce manually when using dp
+            val_acc = output['val_acc']
+            if self.trainer.use_dp or self.trainer.use_ddp2:
+                val_acc = torch.mean(val_acc)
+
+            val_acc_mean += val_acc
+
+        val_loss_mean /= len(outputs)
+        val_acc_mean /= len(outputs)
+
+        tqdm_dict = {'val_loss': val_loss_mean.item(), 'val_acc': val_acc_mean.item()}
+        results = {'progress_bar': tqdm_dict, 'log': tqdm_dict}
+        return results
+
+
+class LightningValidationStepMultipleDataloadersMixin:
+    """
+    Add val_dataloader and validation_step methods for the case
+    when val_dataloader returns multiple dataloaders
+    """
+
+    @data_loader
+    def val_dataloader(self):
+        return [self._dataloader(train=False), self._dataloader(train=False)]
+
+    def validation_step(self, batch, batch_idx, dataloader_idx):
+        """
+        Lightning calls this inside the validation loop
+        :param batch:
+        :return:
+        """
+        x, y = batch
+        x = x.view(x.size(0), -1)
+        y_hat = self.forward(x)
+
+        loss_val = self.loss(y, y_hat)
+
+        # acc
+        labels_hat = torch.argmax(y_hat, dim=1)
+        val_acc = torch.sum(y == labels_hat).item() / (len(y) * 1.0)
+        val_acc = torch.tensor(val_acc)
+
+        if self.on_gpu:
+            val_acc = val_acc.cuda(loss_val.device.index)
+
+        # in DP mode (default) make sure if result is scalar, there's another dim in the beginning
+        if self.trainer.use_dp:
+            loss_val = loss_val.unsqueeze(0)
+            val_acc = val_acc.unsqueeze(0)
+
+        # alternate possible outputs to test
+        if batch_idx % 1 == 0:
+            output = OrderedDict({
+                'val_loss': loss_val,
+                'val_acc': val_acc,
+            })
+            return output
+        if batch_idx % 2 == 0:
+            return val_acc
+
+        if batch_idx % 3 == 0:
+            output = OrderedDict({
+                'val_loss': loss_val,
+                'val_acc': val_acc,
+                'test_dic': {'val_loss_a': loss_val}
+            })
+            return output
+        if batch_idx % 5 == 0:
+            output = OrderedDict({
+                f'val_loss_{dataloader_idx}': loss_val,
+                f'val_acc_{dataloader_idx}': val_acc,
+            })
+            return output
+
+
+class LightningValidationMultipleDataloadersMixin(LightningValidationStepMultipleDataloadersMixin):
+    """
+    Add val_dataloader, validation_step, and validation_end methods for the case
+    when val_dataloader returns multiple dataloaders
+    """
+
+    def validation_end(self, outputs):
+        """
+        Called at the end of validation to aggregate outputs
+        :param outputs: list of individual outputs of each validation step
+        :return:
+        """
+        # if returned a scalar from validation_step, outputs is a list of tensor scalars
+        # we return just the average in this case (if we want)
+        # return torch.stack(outputs).mean()
+        val_loss_mean = 0
+        val_acc_mean = 0
+        i = 0
+        for dl_output in outputs:
+            for output in dl_output:
+                val_loss = output['val_loss']
+
+                # reduce manually when using dp
+                if self.trainer.use_dp:
+                    val_loss = torch.mean(val_loss)
+                val_loss_mean += val_loss
+
+                # reduce manually when using dp
+                val_acc = output['val_acc']
+                if self.trainer.use_dp:
+                    val_acc = torch.mean(val_acc)
+
+                val_acc_mean += val_acc
+                i += 1
+
+        val_loss_mean /= i
+        val_acc_mean /= i
+
+        tqdm_dict = {'val_loss': val_loss_mean.item(), 'val_acc': val_acc_mean.item()}
+        result = {'progress_bar': tqdm_dict}
+        return result
+
+
+class LightningTestStepMixin:
+
+    @data_loader
+    def test_dataloader(self):
+        return self._dataloader(train=False)
+
+    def test_step(self, batch, batch_idx):
+        """
+        Lightning calls this inside the validation loop
+        :param batch:
+        :return:
+        """
+        x, y = batch
+        x = x.view(x.size(0), -1)
+        y_hat = self.forward(x)
+
+        loss_test = self.loss(y, y_hat)
+
+        # acc
+        labels_hat = torch.argmax(y_hat, dim=1)
+        test_acc = torch.sum(y == labels_hat).item() / (len(y) * 1.0)
+        test_acc = torch.tensor(test_acc)
+
+        if self.on_gpu:
+            test_acc = test_acc.cuda(loss_test.device.index)
+
+        # in DP mode (default) make sure if result is scalar, there's another dim in the beginning
+        if self.trainer.use_dp:
+            loss_test = loss_test.unsqueeze(0)
+            test_acc = test_acc.unsqueeze(0)
+
+        # alternate possible outputs to test
+        if batch_idx % 1 == 0:
+            output = OrderedDict({
+                'test_loss': loss_test,
+                'test_acc': test_acc,
+            })
+            return output
+        if batch_idx % 2 == 0:
+            return test_acc
+
+        if batch_idx % 3 == 0:
+            output = OrderedDict({
+                'test_loss': loss_test,
+                'test_acc': test_acc,
+                'test_dic': {'test_loss_a': loss_test}
+            })
+            return output
+
+
+class LightningTestMixin(LightningTestStepMixin):
+    def test_end(self, outputs):
+        """
+        Called at the end of validation to aggregate outputs
+        :param outputs: list of individual outputs of each validation step
+        :return:
+        """
+        # if returned a scalar from test_step, outputs is a list of tensor scalars
+        # we return just the average in this case (if we want)
+        # return torch.stack(outputs).mean()
+        test_loss_mean = 0
+        test_acc_mean = 0
+        for output in outputs:
+            test_loss = output['test_loss']
+
+            # reduce manually when using dp
+            if self.trainer.use_dp:
+                test_loss = torch.mean(test_loss)
+            test_loss_mean += test_loss
+
+            # reduce manually when using dp
+            test_acc = output['test_acc']
+            if self.trainer.use_dp:
+                test_acc = torch.mean(test_acc)
+
+            test_acc_mean += test_acc
+
+        test_loss_mean /= len(outputs)
+        test_acc_mean /= len(outputs)
+
+        tqdm_dict = {'test_loss': test_loss_mean.item(), 'test_acc': test_acc_mean.item()}
+        result = {'progress_bar': tqdm_dict}
+        return result
+
+
+class LightningTestStepMultipleDataloadersMixin:
+
+    @data_loader
+    def test_dataloader(self):
+        return [self._dataloader(train=False), self._dataloader(train=False)]
+
+    def test_step(self, batch, batch_idx, dataloader_idx):
+        """
+        Lightning calls this inside the validation loop
+        :param batch:
+        :return:
+        """
+        x, y = batch
+        x = x.view(x.size(0), -1)
+        y_hat = self.forward(x)
+
+        loss_test = self.loss(y, y_hat)
+
+        # acc
+        labels_hat = torch.argmax(y_hat, dim=1)
+        test_acc = torch.sum(y == labels_hat).item() / (len(y) * 1.0)
+        test_acc = torch.tensor(test_acc)
+
+        if self.on_gpu:
+            test_acc = test_acc.cuda(loss_test.device.index)
+
+        # in DP mode (default) make sure if result is scalar, there's another dim in the beginning
+        if self.trainer.use_dp:
+            loss_test = loss_test.unsqueeze(0)
+            test_acc = test_acc.unsqueeze(0)
+
+        # alternate possible outputs to test
+        if batch_idx % 1 == 0:
+            output = OrderedDict({
+                'test_loss': loss_test,
+                'test_acc': test_acc,
+            })
+            return output
+        if batch_idx % 2 == 0:
+            return test_acc
+
+        if batch_idx % 3 == 0:
+            output = OrderedDict({
+                'test_loss': loss_test,
+                'test_acc': test_acc,
+                'test_dic': {'test_loss_a': loss_test}
+            })
+            return output
+        if batch_idx % 5 == 0:
+            output = OrderedDict({
+                f'test_loss_{dataloader_idx}': loss_test,
+                f'test_acc_{dataloader_idx}': test_acc,
+            })
+            return output
+
+
+class LightningTestMultipleDataloadersMixin(LightningTestStepMultipleDataloadersMixin):
+    def test_end(self, outputs):
+        """
+        Called at the end of validation to aggregate outputs
+        :param outputs: list of individual outputs of each validation step
+        :return:
+        """
+        # if returned a scalar from test_step, outputs is a list of tensor scalars
+        # we return just the average in this case (if we want)
+        # return torch.stack(outputs).mean()
+        test_loss_mean = 0
+        test_acc_mean = 0
+        i = 0
+        for dl_output in outputs:
+            for output in dl_output:
+                test_loss = output['test_loss']
+
+                # reduce manually when using dp
+                if self.trainer.use_dp:
+                    test_loss = torch.mean(test_loss)
+                test_loss_mean += test_loss
+
+                # reduce manually when using dp
+                test_acc = output['test_acc']
+                if self.trainer.use_dp:
+                    test_acc = torch.mean(test_acc)
+
+                test_acc_mean += test_acc
+                i += 1
+
+        test_loss_mean /= i
+        test_acc_mean /= i
+
+        tqdm_dict = {'test_loss': test_loss_mean.item(), 'test_acc': test_acc_mean.item()}
+        result = {'progress_bar': tqdm_dict}
+        return result

pytorch_lightning/trainer/amp_mixin.py

@@ -0,0 +1,25 @@
+try:
+    from apex import amp
+
+    APEX_AVAILABLE = True
+except ImportError:
+    APEX_AVAILABLE = False
+import logging
+
+
+class TrainerAMPMixin(object):
+
+    def init_amp(self, use_amp):
+        self.use_amp = use_amp and APEX_AVAILABLE
+        if self.use_amp:
+            logging.info('using 16bit precision')
+
+        if use_amp and not APEX_AVAILABLE:  # pragma: no cover
+            msg = """
+            You set use_amp=True but do not have apex installed.
+            Install apex first using this guide and rerun with use_amp=True:
+            https://github.com/NVIDIA/apex#linux
+
+            this run will NOT use 16 bit precision
+            """
+            raise ModuleNotFoundError(msg)

pytorch_lightning/trainer/callback_config_mixin.py

@@ -0,0 +1,73 @@
+import os
+
+from pytorch_lightning.callbacks import ModelCheckpoint, EarlyStopping
+from pytorch_lightning.logging import TestTubeLogger
+
+
+class TrainerCallbackConfigMixin(object):
+    def configure_checkpoint_callback(self):
+        """
+        Weight path set in this priority:
+        Checkpoint_callback's path (if passed in).
+        User provided weights_saved_path
+        Otherwise use os.getcwd()
+        """
+        if self.checkpoint_callback is True:
+            # init a default one
+            if self.logger is not None:
+                ckpt_path = os.path.join(
+                    self.default_save_path,
+                    self.logger.name,
+                    f'version_{self.logger.version}',
+                    "checkpoints"
+                )
+            else:
+                ckpt_path = os.path.join(self.default_save_path, "checkpoints")
+
+            self.checkpoint_callback = ModelCheckpoint(
+                filepath=ckpt_path
+            )
+        elif self.checkpoint_callback is False:
+            self.checkpoint_callback = None
+
+        if self.checkpoint_callback:
+            # set the path for the callbacks
+            self.checkpoint_callback.save_function = self.save_checkpoint
+
+            # if checkpoint callback used, then override the weights path
+            self.weights_save_path = self.checkpoint_callback.filepath
+
+        # if weights_save_path is still none here, set to current working dir
+        if self.weights_save_path is None:
+            self.weights_save_path = self.default_save_path
+
+    def configure_early_stopping(self, early_stop_callback, logger):
+        if early_stop_callback is True:
+            self.early_stop_callback = EarlyStopping(
+                monitor='val_loss',
+                patience=3,
+                verbose=True,
+                mode='min'
+            )
+            self.enable_early_stop = True
+        elif not early_stop_callback:
+            self.early_stop_callback = None
+            self.enable_early_stop = False
+        else:
+            self.early_stop_callback = early_stop_callback
+            self.enable_early_stop = True
+
+        # configure logger
+        if logger is True:
+            # default logger
+            self.logger = TestTubeLogger(
+                save_dir=self.default_save_path,
+                version=self.slurm_job_id,
+                name='lightning_logs'
+            )
+            self.logger.rank = 0
+        elif logger is False:
+            self.logger = None
+        else:
+            self.logger = logger
+            self.logger.rank = 0

pytorch_lightning/trainer/data_loading_mixin.py

@@ -0,0 +1,190 @@
+import warnings
+
+import torch.distributed as dist
+from torch.utils.data import IterableDataset
+from torch.utils.data.distributed import DistributedSampler
+
+from pytorch_lightning.utilities.debugging import MisconfigurationException
+
+try:
+    from apex import amp
+
+    APEX_AVAILABLE = True
+except ImportError:
+    APEX_AVAILABLE = False
+
+
+class TrainerDataLoadingMixin(object):
+    def init_train_dataloader(self, model):
+        """
+        Dataloaders are provided by the model
+        :param model:
+        :return:
+        """
+        self.get_train_dataloader = model.train_dataloader
+
+        # determine number of training batches
+        if isinstance(self.get_train_dataloader(), IterableDataset):
+            self.nb_training_batches = float('inf')
+        else:
+            self.nb_training_batches = len(self.get_train_dataloader())
+            self.nb_training_batches = int(self.nb_training_batches * self.train_percent_check)
+
+        # determine when to check validation
+        # if int passed in, val checks that often
+        # otherwise, it checks in [0, 1.0] % range of a training epoch
+        if isinstance(self.val_check_interval, int):
+            self.val_check_batch = self.val_check_interval
+        else:
+            self.val_check_batch = int(self.nb_training_batches * self.val_check_interval)
+            self.val_check_batch = max(1, self.val_check_batch)
+
+        on_ddp = self.use_ddp or self.use_ddp2
+        if on_ddp and not isinstance(self.get_train_dataloader().sampler, DistributedSampler):
+            msg = """
+            You're using multiple gpus and multiple nodes without using a DistributedSampler
+            to assign a subset of your data to each process. To silence this warning, pass a
+            DistributedSampler to your DataLoader.
+
+            ie: this:
+            dataset = myDataset()
+            dataloader = Dataloader(dataset)
+
+            becomes:
+            dataset = myDataset()
+            dist_sampler = torch.utils.data.distributed.DistributedSampler(dataset)
+            dataloader = Dataloader(dataset, sampler=dist_sampler)
+
+            If you want each process to load the full dataset, ignore this warning.
+            """
+            if msg not in self.shown_warnings and self.proc_rank == 0:
+                self.shown_warnings.add(msg)
+                warnings.warn(msg)
+
+    def init_val_dataloader(self, model):
+        """
+        Dataloaders are provided by the model
+        :param model:
+        :return:
+        """
+        self.get_val_dataloaders = model.val_dataloader
+
+        # determine number of validation batches
+        # val datasets could be none, 1 or 2+
+        if self.get_val_dataloaders() is not None:
+            self.nb_val_batches = sum(len(dataloader) for dataloader in self.get_val_dataloaders())
+            self.nb_val_batches = int(self.nb_val_batches * self.val_percent_check)
+            self.nb_val_batches = max(1, self.nb_val_batches)
+
+        on_ddp = self.use_ddp or self.use_ddp2
+        if on_ddp and self.get_val_dataloaders() is not None:
+            for dataloader in self.get_val_dataloaders():
+                if not isinstance(dataloader.sampler, DistributedSampler):
+                    msg = """
+                    Your val_dataloader(s) don't use DistributedSampler.
+
+                    You're using multiple gpus and multiple nodes without using a
+                    DistributedSampler to assign a subset of your data to each process.
+                    To silence this warning, pass a DistributedSampler to your DataLoader.
+
+                    ie: this:
+                    dataset = myDataset()
+                    dataloader = Dataloader(dataset)
+
+                    becomes:
+                    dataset = myDataset()
+                    dist_sampler = torch.utils.data.distributed.DistributedSampler(dataset)
+                    dataloader = Dataloader(dataset, sampler=dist_sampler)
+
+                    If you want each process to load the full dataset, ignore this warning.
+                    """
+                    if msg not in self.shown_warnings and self.proc_rank == 0:
+                        self.shown_warnings.add(msg)
+                        warnings.warn(msg)
+                    break
+
+    def init_test_dataloader(self, model):
+        """
+        Dataloaders are provided by the model
+        :param model:
+        :return:
+        """
+
+        self.get_test_dataloaders = model.test_dataloader
+
+        # determine number of test batches
+        if self.get_test_dataloaders() is not None:
+            len_sum = sum(len(dataloader) for dataloader in self.get_test_dataloaders())
+            self.nb_test_batches = len_sum
+            self.nb_test_batches = int(self.nb_test_batches * self.test_percent_check)
+            self.nb_test_batches = max(1, self.nb_test_batches)
+
+        on_ddp = self.use_ddp or self.use_ddp2
+        if on_ddp and self.get_test_dataloaders() is not None:
+            for dataloader in self.get_test_dataloaders():
+                if not isinstance(dataloader.sampler, DistributedSampler):
+                    msg = """
+                    Your test_dataloader(s) don't use DistributedSampler.
+
+                    You're using multiple gpus and multiple nodes without using a
+                    DistributedSampler to assign a subset of your data to each process.
+                    To silence this warning, pass a DistributedSampler to your DataLoader.
+
+                    ie: this:
+                    dataset = myDataset()
+                    dataloader = Dataloader(dataset)
+
+                    becomes:
+                    dataset = myDataset()
+                    dist_sampler = torch.utils.data.distributed.DistributedSampler(dataset)
+                    dataloader = Dataloader(dataset, sampler=dist_sampler)
+
+                    If you want each process to load the full dataset, ignore this warning.
+                    """
+                    if msg not in self.shown_warnings and self.proc_rank == 0:
+                        self.shown_warnings.add(msg)
+                        warnings.warn(msg)
+                    break
+
+    def get_dataloaders(self, model):
+        """
+        Dataloaders are provided by the model
+        :param model:
+        :return:
+        """
+
+        self.init_train_dataloader(model)
+        self.init_test_dataloader(model)
+        self.init_val_dataloader(model)
+
+        if self.use_ddp or self.use_ddp2:
+            # wait for all processes to catch up
+            dist.barrier()
+
+            # load each dataloader
+            self.get_train_dataloader()
+            self.get_test_dataloaders()
+            self.get_val_dataloaders()
+
+        # support IterableDataset for train data
+        self.is_iterable_train_dataloader = isinstance(self.get_train_dataloader(), IterableDataset)
+        if self.is_iterable_train_dataloader and not isinstance(self.val_check_interval, int):
+            m = '''
+            When using an iterableDataset for train_dataloader,
+            Trainer(val_check_interval) must be an int.
+            An int k specifies checking validation every k training batches
+            '''
+            raise MisconfigurationException(m)
+
+    def determine_data_use_amount(self, train_percent_check, val_percent_check,
+                                  test_percent_check, overfit_pct):
+        """
+        Use less data for debugging purposes
+        """
+        self.train_percent_check = train_percent_check
+        self.val_percent_check = val_percent_check
+        self.test_percent_check = test_percent_check
+        if overfit_pct > 0:
+            self.train_percent_check = overfit_pct
+            self.val_percent_check = overfit_pct
+            self.test_percent_check = overfit_pct

pytorch_lightning/trainer/ddp_mixin.py

@@ -0,0 +1,193 @@
+import os
+import re
+import warnings
+import logging
+
+import torch
+
+from pytorch_lightning.utilities.debugging import MisconfigurationException
+
+try:
+    from apex import amp
+
+    APEX_AVAILABLE = True
+except ImportError:
+    APEX_AVAILABLE = False
+
+
+class TrainerDDPMixin(object):
+    def set_distributed_mode(self, distributed_backend, nb_gpu_nodes):
+        # skip for CPU
+        if self.num_gpus == 0:
+            return
+
+        # single GPU case
+        # in single gpu case we allow ddp so we can train on multiple
+        # nodes, 1 gpu per node
+        if self.num_gpus == 1:
+            self.single_gpu = True
+
+            if distributed_backend is not None:
+                self.use_dp = distributed_backend == 'dp'
+                self.use_ddp = distributed_backend == 'ddp'
+                self.use_ddp2 = distributed_backend == 'ddp2'
+
+                # disable single gpu when using ddp2
+                if self.use_ddp2:
+                    self.single_gpu = False
+
+        # multiple GPU case
+        elif self.num_gpus > 1:
+            if distributed_backend is not None:
+                # DP, DDP case
+                self.use_dp = distributed_backend == 'dp'
+                self.use_ddp = distributed_backend == 'ddp'
+                self.use_ddp2 = distributed_backend == 'ddp2'
+
+            elif distributed_backend is None:
+                m = 'When using multiple GPUs set ' \
+                    'Trainer(distributed_backend=dp) (or ddp)'
+                raise MisconfigurationException(m)
+
+        # throw error to force user ddp or ddp2 choice
+        if nb_gpu_nodes > 1 and not (self.use_ddp2 or self.use_ddp):  # pragma: no cover
+            w = 'DataParallel does not support nb_gpu_nodes > 1. ' \
+                'Switching to DistributedDataParallel for you. ' \
+                'To silence this warning set distributed_backend=ddp' \
+                'or distributed_backend=ddp2'
+            raise MisconfigurationException(w)
+
+        logging.info(f'gpu available: {torch.cuda.is_available()}, used: {self.on_gpu}')
+
+    def configure_slurm_ddp(self, nb_gpu_nodes):
+        self.is_slurm_managing_tasks = False
+
+        # extract SLURM flag vars
+        # whenever we have the correct number of tasks, we let slurm manage processes
+        # otherwise we launch the required number of processes
+        if self.use_ddp:
+            self.nb_requested_gpus = self.num_gpus * nb_gpu_nodes
+            self.nb_slurm_tasks = 0
+            try:
+                self.nb_slurm_tasks = int(os.environ['SLURM_NTASKS'])
+                self.is_slurm_managing_tasks = self.nb_slurm_tasks == self.nb_requested_gpus
+
+                # in interactive mode we don't manage tasks
+                job_name = os.environ['SLURM_JOB_NAME']
+                if job_name == 'bash':
+                    self.is_slurm_managing_tasks = False
+
+            except Exception:
+                # likely not on slurm, so set the slurm managed flag to false
+                self.is_slurm_managing_tasks = False
+
+        # used for tests only, set this flag to simulate slurm managing a task
+        try:
+            should_fake = int(os.environ['FAKE_SLURM_MANAGING_TASKS'])
+            if should_fake:
+                self.is_slurm_managing_tasks = True
+        except Exception as e:
+            pass
+
+    def set_nvidia_flags(self, is_slurm_managing_tasks, data_parallel_device_ids):
+        if data_parallel_device_ids is None:
+            return
+
+        # set the correct cuda visible devices (using pci order)
+        os.environ["CUDA_DEVICE_ORDER"] = "PCI_BUS_ID"
+
+        # when slurm is managing the task it sets the visible devices
+        if not is_slurm_managing_tasks:
+            if type(data_parallel_device_ids) is int:
+                id_str = ','.join(str(x) for x in list(range(data_parallel_device_ids)))
+                os.environ["CUDA_VISIBLE_DEVICES"] = id_str
+            else:
+                gpu_str = ','.join([str(x) for x in data_parallel_device_ids])
+                os.environ["CUDA_VISIBLE_DEVICES"] = gpu_str
+
+        logging.info(f'VISIBLE GPUS: {os.environ["CUDA_VISIBLE_DEVICES"]}')
+
+    def ddp_train(self, gpu_nb, model):
+        """
+        Entry point into a DP thread
+        :param gpu_nb:
+        :param model:
+        :param cluster_obj:
+        :return:
+        """
+        # node rank using relative slurm id
+        # otherwise default to node rank 0
+        try:
+            node_id = os.environ['SLURM_NODEID']
+            self.node_rank = int(node_id)
+        except Exception:
+            self.node_rank = 0
+
+        # show progressbar only on progress_rank 0
+        self.show_progress_bar = self.show_progress_bar and self.node_rank == 0 and gpu_nb == 0
+
+        # determine which process we are and world size
+        if self.use_ddp:
+            self.proc_rank = self.node_rank * self.num_gpus + gpu_nb
+            self.world_size = self.nb_gpu_nodes * self.num_gpus
+
+        elif self.use_ddp2:
+            self.proc_rank = self.node_rank
+            self.world_size = self.nb_gpu_nodes
+
+        # let the exp know the rank to avoid overwriting logs
+        if self.logger is not None:
+            self.logger.rank = self.proc_rank
+
+        # set up server using proc 0's ip address
+        # try to init for 20 times at max in case ports are taken
+        # where to store ip_table
+        model.trainer = self
+        model.init_ddp_connection(self.proc_rank, self.world_size)
+
+        # CHOOSE OPTIMIZER
+        # allow for lr schedulers as well
+        self.optimizers, self.lr_schedulers = self.init_optimizers(model.configure_optimizers())
+
+        # MODEL
+        # copy model to each gpu
+        if self.distributed_backend == 'ddp':
+            torch.cuda.set_device(gpu_nb)
+        model.cuda(gpu_nb)
+
+        # set model properties before going into wrapper
+        self.copy_trainer_model_properties(model)
+
+        # override root GPU
+        self.root_gpu = gpu_nb
+
+        # AMP
+        # run through amp wrapper before going to distributed DP
+        if self.use_amp:
+            # An example
+            model, optimizers = model.configure_apex(amp, model, self.optimizers, self.amp_level)
+            self.optimizers = optimizers
+
+        # DDP2 uses all GPUs on the machine
+        if self.distributed_backend == 'ddp':
+            device_ids = [gpu_nb]
+        elif self.use_ddp2:
+            device_ids = self.data_parallel_device_ids
+
+        # allow user to configure ddp
+        model = model.configure_ddp(model, device_ids)
+
+        # continue training routine
+        self.run_pretrain_routine(model)
+
+    def resolve_root_node_address(self, root_node):
+        if '[' in root_node:
+            name = root_node.split('[')[0]
+            number = root_node.split(',')[0]
+            if '-' in number:
+                number = number.split('-')[0]
+
+            number = re.sub('[^0-9]', '', number)
+            root_node = name + number
+
+        return root_node

pytorch_lightning/trainer/dp_mixin.py

@@ -0,0 +1,217 @@
+import torch
+
+from pytorch_lightning.pt_overrides.override_data_parallel import (
+    LightningDistributedDataParallel, LightningDataParallel)
+from pytorch_lightning.utilities.debugging import MisconfigurationException
+
+try:
+    from apex import amp
+
+    APEX_AVAILABLE = True
+except ImportError:
+    APEX_AVAILABLE = False
+
+
+class TrainerDPMixin(object):
+    def copy_trainer_model_properties(self, model):
+        if isinstance(model, LightningDataParallel):
+            ref_model = model.module
+        elif isinstance(model, LightningDistributedDataParallel):
+            ref_model = model.module
+        else:
+            ref_model = model
+
+        for m in [model, ref_model]:
+            m.trainer = self
+            m.on_gpu = self.on_gpu
+            m.use_dp = self.use_dp
+            m.use_ddp2 = self.use_ddp2
+            m.use_ddp = self.use_ddp
+            m.use_amp = self.use_amp
+            m.testing = self.testing
+            m.single_gpu = self.single_gpu
+
+    def transfer_batch_to_gpu(self, batch, gpu_id):
+        # base case: object can be directly moved using `cuda` or `to`
+        if callable(getattr(batch, 'cuda', None)):
+            return batch.cuda(gpu_id)
+
+        elif callable(getattr(batch, 'to', None)):
+            return batch.to(torch.device('cuda', gpu_id))
+
+        # when list
+        elif isinstance(batch, list):
+            for i, x in enumerate(batch):
+                batch[i] = self.transfer_batch_to_gpu(x, gpu_id)
+            return batch
+
+        # when tuple
+        elif isinstance(batch, tuple):
+            batch = list(batch)
+            for i, x in enumerate(batch):
+                batch[i] = self.transfer_batch_to_gpu(x, gpu_id)
+            return tuple(batch)
+
+        # when dict
+        elif isinstance(batch, dict):
+            for k, v in batch.items():
+                batch[k] = self.transfer_batch_to_gpu(v, gpu_id)
+
+            return batch
+
+        # nothing matches, return the value as is without transform
+        return batch
+
+    def single_gpu_train(self, model):
+        # CHOOSE OPTIMIZER
+        # allow for lr schedulers as well
+        self.optimizers, self.lr_schedulers = self.init_optimizers(model.configure_optimizers())
+
+        model.cuda(self.root_gpu)
+
+        if self.use_amp:
+            # An example
+            model, optimizers = model.configure_apex(amp, model, self.optimizers, self.amp_level)
+            self.optimizers = optimizers
+
+        self.run_pretrain_routine(model)
+
+    def dp_train(self, model):
+
+        # CHOOSE OPTIMIZER
+        # allow for lr schedulers as well
+        self.optimizers, self.lr_schedulers = self.init_optimizers(model.configure_optimizers())
+
+        model.cuda(self.root_gpu)
+
+        # check for this bug (amp + dp + !01 doesn't work)
+        # https://github.com/NVIDIA/apex/issues/227
+        if self.use_dp and self.use_amp:
+            m = f"""
+            Amp level {self.amp_level} with DataParallel is not supported.
+            See this note from NVIDIA for more info: https://github.com/NVIDIA/apex/issues/227.
+            We recommend you switch to ddp if you want to use amp
+            """
+            raise MisconfigurationException(m)
+
+        # create list of device ids
+        device_ids = self.data_parallel_device_ids
+        if type(device_ids) is int:
+            device_ids = list(range(device_ids))
+
+        model = LightningDataParallel(model, device_ids=device_ids)
+
+        self.run_pretrain_routine(model)
+
+
+def normalize_parse_gpu_string_input(s):
+    if type(s) is str:
+        if s == '-1':
+            return -1
+        else:
+            return [int(x.strip()) for x in s.split(',')]
+    else:
+        return s
+
+
+def get_all_available_gpus():
+    """
+    :return: a list of all available gpus
+    """
+    return list(range(torch.cuda.device_count()))
+
+
+def check_gpus_data_type(gpus):
+    """
+    :param gpus: gpus parameter as passed to the Trainer
+        Function checks that it is one of: None, Int, String or List
+        Throws otherwise
+    :return: return unmodified gpus variable
+    """
+
+    if (gpus is not None and
+        type(gpus) is not int and
+        type(gpus) is not str and
+        type(gpus) is not list):    # noqa E129
+        raise MisconfigurationException("GPUs must be int, string or list of ints or None.")
+
+
+def normalize_parse_gpu_input_to_list(gpus):
+    assert gpus is not None
+    if isinstance(gpus, list):
+        return gpus
+    else:  # must be an int
+        if not gpus:  # gpus==0
+            return None
+        elif gpus == -1:
+            return get_all_available_gpus()
+        else:
+            return list(range(gpus))
+
+
+def sanitize_gpu_ids(gpus):
+    """
+    :param gpus: list of ints corresponding to GPU indices
+        Checks that each of the GPUs in the list is actually available.
+        Throws if any of the GPUs is not available.
+    :return: unmodified gpus variable
+    """
+    all_available_gpus = get_all_available_gpus()
+    for gpu in gpus:
+        if gpu not in all_available_gpus:
+            message = f"""
+            Non-available gpu index {gpu} specified:
+            Available gpu indices are: {all_available_gpus}
+            """
+            raise MisconfigurationException(message)
+    return gpus
+
+
+def parse_gpu_ids(gpus):
+    """
+    :param gpus: Int, string or list
+        An int -1 or string '-1' indicate that all available GPUs should be used.
+        A list of ints or a string containing list of comma separated integers
+        indicates specific GPUs to use
+        An int 0 means that no GPUs should be used
+        Any int N > 0 indicates that GPUs [0..N) should be used.
+    :return: List of gpus to be used
+
+        If no GPUs are available but the value of gpus variable indicates request for GPUs
+        then a misconfiguration exception is raised.
+    """
+
+    # Check that gpus param is None, Int, String or List
+    check_gpus_data_type(gpus)
+
+    # Handle the case when no gpus are requested
+    if gpus is None or type(gpus) is int and gpus == 0:
+        return None
+
+    # We know user requested GPUs therefore if some of the
+    # requested GPUs are not available an exception is thrown.
+
+    gpus = normalize_parse_gpu_string_input(gpus)
+    gpus = normalize_parse_gpu_input_to_list(gpus)
+    gpus = sanitize_gpu_ids(gpus)
+
+    if not gpus:
+        raise MisconfigurationException("GPUs requested but non are available.")
+    return gpus
+
+
+def determine_root_gpu_device(gpus):
+    """
+    :param gpus: non empty list of ints representing which gpus to use
+    :return: designated root GPU device
+    """
+    if gpus is None:
+        return None
+
+    assert isinstance(gpus, list), "gpus should be a list"
+    assert len(gpus), "gpus should be a non empty list"
+
+    # set root gpu
+    root_gpu = gpus[0]
+
+    return root_gpu

pytorch_lightning/trainer/evaluation_loop_mixin.py

@@ -0,0 +1,192 @@
+import torch
+import tqdm
+
+from pytorch_lightning.utilities.debugging import MisconfigurationException
+
+
+class TrainerEvaluationLoopMixin(object):
+
+    def evaluate(self, model, dataloaders, max_batches, test=False):
+        """
+        Run evaluation code
+        :param model: PT model
+        :param dataloaders: list of PT dataloaders
+        :param max_batches: Scalar
+        :param test: boolean
+        :return:
+        """
+        # enable eval mode
+        model.zero_grad()
+        model.eval()
+
+        # copy properties for forward overrides
+        self.copy_trainer_model_properties(model)
+
+        # disable gradients to save memory
+        torch.set_grad_enabled(False)
+
+        # bookkeeping
+        outputs = []
+
+        # run training
+        for dataloader_idx, dataloader in enumerate(dataloaders):
+            dl_outputs = []
+            for batch_idx, batch in enumerate(dataloader):
+
+                if batch is None:  # pragma: no cover
+                    continue
+
+                # stop short when on fast_dev_run (sets max_batch=1)
+                if batch_idx >= max_batches:
+                    break
+
+                # -----------------
+                # RUN EVALUATION STEP
+                # -----------------
+                output = self.evaluation_forward(model,
+                                                 batch,
+                                                 batch_idx,
+                                                 dataloader_idx,
+                                                 test)
+
+                # track outputs for collation
+                dl_outputs.append(output)
+
+                # batch done
+                if test:
+                    self.test_progress_bar.update(1)
+                else:
+                    self.val_progress_bar.update(1)
+                    self.main_progress_bar.update(1)
+            outputs.append(dl_outputs)
+
+        eval_results = {}
+
+        # with a single dataloader don't pass an array
+        if len(dataloaders) == 1:
+            outputs = outputs[0]
+
+        # give model a chance to do something with the outputs (and method defined)
+        model = self.get_model()
+        if test and self.is_overriden('test_end'):
+            eval_results = model.test_end(outputs)
+        elif self.is_overriden('validation_end'):
+            eval_results = model.validation_end(outputs)
+
+        # enable train mode again
+        model.train()
+
+        # enable gradients to save memory
+        torch.set_grad_enabled(True)
+
+        return eval_results
+
+    def run_evaluation(self, test=False):
+        # when testing make sure user defined a test step
+        can_run_test_step = False
+        if test:
+            can_run_test_step = self.is_overriden('test_step') and self.is_overriden('test_end')
+            if not can_run_test_step:
+                m = '''You called .test() without defining a test step or test_end.
+                Please define and try again'''
+                raise MisconfigurationException(m)
+
+        # validate only if model has validation_step defined
+        # test only if test_step or validation_step are defined
+        run_val_step = self.is_overriden('validation_step')
+
+        if run_val_step or can_run_test_step:
+
+            # hook
+            model = self.get_model()
+            model.on_pre_performance_check()
+
+            # select dataloaders
+            if test:
+                dataloaders = self.get_test_dataloaders()
+                max_batches = self.nb_test_batches
+            else:
+                # val
+                dataloaders = self.get_val_dataloaders()
+                max_batches = self.nb_val_batches
+
+            # cap max batches to 1 when using fast_dev_run
+            if self.fast_dev_run:
+                max_batches = 1
+
+            # init validation or test progress bar
+            # main progress bar will already be closed when testing so initial position is free
+            position = 2 * self.process_position + (not test)
+            desc = 'Testing' if test else 'Validating'
+            pbar = tqdm.tqdm(desc=desc, total=max_batches, leave=test, position=position,
+                             disable=not self.show_progress_bar, dynamic_ncols=True,
+                             unit='batch')
+            setattr(self, f'{"test" if test else "val"}_progress_bar', pbar)
+
+            # run evaluation
+            eval_results = self.evaluate(self.model,
+                                         dataloaders,
+                                         max_batches,
+                                         test)
+            _, prog_bar_metrics, log_metrics, callback_metrics, _ = self.process_output(
+                eval_results)
+
+            # add metrics to prog bar
+            self.add_tqdm_metrics(prog_bar_metrics)
+
+            # log metrics
+            self.log_metrics(log_metrics, {})
+
+            # track metrics for callbacks
+            self.callback_metrics = callback_metrics
+
+            # hook
+            model.on_post_performance_check()
+
+            # add model specific metrics
+            tqdm_metrics = self.training_tqdm_dict
+            if not test:
+                self.main_progress_bar.set_postfix(**tqdm_metrics)
+
+            # close progress bar
+            if test:
+                self.test_progress_bar.close()
+            else:
+                self.val_progress_bar.close()
+
+        # model checkpointing
+        if self.proc_rank == 0 and self.checkpoint_callback is not None and not test:
+            self.checkpoint_callback.on_epoch_end(epoch=self.current_epoch,
+                                                  logs=self.callback_metrics)
+
+    def evaluation_forward(self, model, batch, batch_idx, dataloader_idx, test=False):
+        # make dataloader_idx arg in validation_step optional
+        args = [batch, batch_idx]
+
+        if test and len(self.get_test_dataloaders()) > 1:
+            args.append(dataloader_idx)
+
+        elif not test and len(self.get_val_dataloaders()) > 1:
+            args.append(dataloader_idx)
+
+        # handle DP, DDP forward
+        if self.use_ddp or self.use_dp or self.use_ddp2:
+            output = model(*args)
+            return output
+
+        # single GPU
+        if self.single_gpu:
+            # for single GPU put inputs on gpu manually
+            root_gpu = 0
+            if type(self.data_parallel_device_ids) is list:
+                root_gpu = self.data_parallel_device_ids[0]
+            batch = self.transfer_batch_to_gpu(batch, root_gpu)
+            args[0] = batch
+
+        # CPU
+        if test:
+            output = model.test_step(*args)
+        else:
+            output = model.validation_step(*args)
+
+        return output

pytorch_lightning/trainer/ignored_warnings.py

@@ -0,0 +1,14 @@
+import warnings
+
+
+def ignore_scalar_return_in_dp():
+    # Users get confused by this warning so we silence it
+    m_1 = """
+    Was asked to gather along dimension 0, but all
+    input tensors were scalars; will instead unsqueeze
+    and return a vector.
+    """
+    warnings.filterwarnings('ignore', message=m_1)
+
+
+ignore_scalar_return_in_dp()

pytorch_lightning/trainer/logging_mixin.py

@@ -0,0 +1,167 @@
+import torch
+
+from pytorch_lightning.root_module import memory
+
+
+class TrainerLoggingMixin(object):
+
+    def log_metrics(self, metrics, grad_norm_dic):
+        """
+        Logs the metric dict passed in
+        :param metrics:
+        :param grad_norm_dic:
+        :return:
+        """
+        # added metrics by Lightning for convenience
+        metrics['epoch'] = self.current_epoch
+
+        # add gpu memory
+        if self.on_gpu and self.log_gpu_memory:
+            mem_map = memory.get_memory_profile(self.log_gpu_memory)
+            metrics.update(mem_map)
+
+        # add norms
+        metrics.update(grad_norm_dic)
+
+        # turn all tensors to scalars
+        scalar_metrics = self.metrics_to_scalars(metrics)
+
+        # log actual metrics
+        if self.proc_rank == 0 and self.logger is not None:
+            self.logger.log_metrics(scalar_metrics, step_num=self.global_step)
+            self.logger.save()
+
+    def add_tqdm_metrics(self, metrics):
+        for k, v in metrics.items():
+            if type(v) is torch.Tensor:
+                v = v.item()
+
+            self.tqdm_metrics[k] = v
+
+    def metrics_to_scalars(self, metrics):
+        new_metrics = {}
+        for k, v in metrics.items():
+            if isinstance(v, torch.Tensor):
+                v = v.item()
+
+            if type(v) is dict:
+                v = self.metrics_to_scalars(v)
+
+            new_metrics[k] = v
+
+        return new_metrics
+
+    def process_output(self, output, train=False):
+        """
+        Reduces output according to the training mode.
+        Separates loss from logging and tqdm metrics
+        :param output:
+        :return:
+        """
+        # ---------------
+        # EXTRACT CALLBACK KEYS
+        # ---------------
+        # all keys not progress_bar or log are candidates for callbacks
+        callback_metrics = {}
+        for k, v in output.items():
+            if k not in ['progress_bar', 'log', 'hiddens']:
+                callback_metrics[k] = v
+
+        if train and (self.use_dp or self.use_ddp2):
+            nb_gpus = self.num_gpus
+            callback_metrics = self.reduce_distributed_output(callback_metrics, nb_gpus)
+
+        for k, v in callback_metrics.items():
+            callback_metrics[k] = v.item()
+
+        # ---------------
+        # EXTRACT PROGRESS BAR KEYS
+        # ---------------
+        try:
+            progress_output = output['progress_bar']
+
+            # reduce progress metrics for tqdm when using dp
+            if train and (self.use_dp or self.use_ddp2):
+                nb_gpus = self.num_gpus
+                progress_output = self.reduce_distributed_output(progress_output, nb_gpus)
+
+            progress_bar_metrics = progress_output
+        except Exception:
+            progress_bar_metrics = {}
+
+        # ---------------
+        # EXTRACT LOGGING KEYS
+        # ---------------
+        # extract metrics to log to experiment
+        try:
+            log_output = output['log']
+
+            # reduce progress metrics for tqdm when using dp
+            if train and (self.use_dp or self.use_ddp2):
+                nb_gpus = self.num_gpus
+                log_output = self.reduce_distributed_output(log_output, nb_gpus)
+
+            log_metrics = log_output
+        except Exception:
+            log_metrics = {}
+
+        # ---------------
+        # EXTRACT LOSS
+        # ---------------
+        # if output dict doesn't have the keyword loss
+        # then assume the output=loss if scalar
+        loss = None
+        if train:
+            try:
+                loss = output['loss']
+            except Exception:
+                if type(output) is torch.Tensor:
+                    loss = output
+                else:
+                    raise RuntimeError(
+                        'No `loss` value in the dictionary returned from `model.training_step()`.'
+                    )
+
+            # when using dp need to reduce the loss
+            if self.use_dp or self.use_ddp2:
+                loss = self.reduce_distributed_output(loss, self.num_gpus)
+
+        # ---------------
+        # EXTRACT HIDDEN
+        # ---------------
+        hiddens = output.get('hiddens')
+
+        # use every metric passed in as a candidate for callback
+        callback_metrics.update(progress_bar_metrics)
+        callback_metrics.update(log_metrics)
+
+        # convert tensors to numpy
+        for k, v in callback_metrics.items():
+            if isinstance(v, torch.Tensor):
+                callback_metrics[k] = v.item()
+
+        return loss, progress_bar_metrics, log_metrics, callback_metrics, hiddens
+
+    def reduce_distributed_output(self, output, nb_gpus):
+        if nb_gpus <= 1:
+            return output
+
+        # when using DP, we get one output per gpu
+        # average outputs and return
+        if type(output) is torch.Tensor:
+            return output.mean()
+
+        for k, v in output.items():
+            # recurse on nested dics
+            if isinstance(output[k], dict):
+                output[k] = self.reduce_distributed_output(output[k], nb_gpus)
+
+            # do nothing when there's a scalar
+            elif isinstance(output[k], torch.Tensor) and output[k].dim() == 0:
+                pass
+
+            # reduce only metrics that have the same nb of gpus
+            elif output[k].size(0) == nb_gpus:
+                reduced = torch.mean(output[k])
+                output[k] = reduced
+        return output

pytorch_lightning/trainer/model_hooks_mixin.py

@@ -0,0 +1,17 @@
+from pytorch_lightning.root_module.root_module import LightningModule
+
+
+class TrainerModelHooksMixin(object):
+
+    def is_function_implemented(self, f_name):
+        model = self.get_model()
+        f_op = getattr(model, f_name, None)
+        return callable(f_op)
+
+    def is_overriden(self, f_name):
+        model = self.get_model()
+        super_object = LightningModule
+
+        # when code pointers are different, it was overriden
+        is_overriden = getattr(model, f_name).__code__ is not getattr(super_object, f_name).__code__
+        return is_overriden

pytorch_lightning/trainer/train_loop_mixin.py

@@ -0,0 +1,309 @@
+import numpy as np
+import tqdm
+
+try:
+    from apex import amp
+
+    APEX_AVAILABLE = True
+except ImportError:
+    APEX_AVAILABLE = False
+
+
+class TrainerTrainLoopMixin(object):
+
+    def train(self):
+        # run all epochs
+        for epoch_nb in range(self.current_epoch, self.max_nb_epochs):
+            # set seed for distributed sampler (enables shuffling for each epoch)
+            if self.use_ddp and hasattr(self.get_train_dataloader().sampler, 'set_epoch'):
+                self.get_train_dataloader().sampler.set_epoch(epoch_nb)
+
+            # get model
+            model = self.get_model()
+
+            # update training progress in trainer and model
+            model.current_epoch = epoch_nb
+            self.current_epoch = epoch_nb
+
+            # val can be checked multiple times in epoch
+            is_val_epoch = (self.current_epoch + 1) % self.check_val_every_n_epoch == 0
+            val_checks_per_epoch = self.nb_training_batches // self.val_check_batch
+            val_checks_per_epoch = val_checks_per_epoch if is_val_epoch else 0
+
+            # total batches includes multiple val checks
+            self.total_batches = (self.nb_training_batches +
+                                  self.nb_val_batches * val_checks_per_epoch)
+            self.batch_loss_value = 0  # accumulated grads
+
+            if self.fast_dev_run:
+                # limit the number of batches to 2 (1 train and 1 val) in fast_dev_run
+                nb_iterations = 2
+            elif self.is_iterable_train_dataloader:
+                # for iterable train loader, the progress bar never ends
+                nb_iterations = None
+            else:
+                nb_iterations = self.total_batches
+
+            # reset progress bar
+            # .reset() doesn't work on disabled progress bar so we should check
+            if not self.main_progress_bar.disable:
+                self.main_progress_bar.reset(nb_iterations)
+            desc = f'Epoch {epoch_nb + 1}' if not self.is_iterable_train_dataloader else ''
+            self.main_progress_bar.set_description(desc)
+
+            # changing gradient according accumulation_scheduler
+            self.accumulation_scheduler.on_epoch_begin(epoch_nb, self)
+
+            # -----------------
+            # RUN TNG EPOCH
+            # -----------------
+            self.run_training_epoch()
+
+            # update LR schedulers
+            if self.lr_schedulers is not None:
+                for lr_scheduler in self.lr_schedulers:
+                    lr_scheduler.step(self.current_epoch)
+
+            # early stopping
+            met_min_epochs = epoch_nb > self.min_nb_epochs
+            if self.enable_early_stop and (met_min_epochs or self.fast_dev_run):
+                should_stop = self.early_stop_callback.on_epoch_end(epoch=epoch_nb,
+                                                                    logs=self.callback_metrics)
+                # stop training
+                stop = should_stop and met_min_epochs
+                if stop:
+                    self.main_progress_bar.close()
+                    return
+
+        self.main_progress_bar.close()
+
+        if self.logger is not None:
+            self.logger.finalize("success")
+
+    def run_training_epoch(self):
+        # before epoch hook
+        if self.is_function_implemented('on_epoch_start'):
+            model = self.get_model()
+            model.on_epoch_start()
+
+        # run epoch
+        for batch_nb, batch in enumerate(self.get_train_dataloader()):
+            self.batch_nb = batch_nb
+
+            model = self.get_model()
+            model.global_step = self.global_step
+
+            # ---------------
+            # RUN TRAIN STEP
+            # ---------------
+            output = self.run_training_batch(batch, batch_nb)
+            batch_result, grad_norm_dic, batch_step_metrics = output
+
+            # when returning -1 from train_step, we end epoch early
+            early_stop_epoch = batch_result == -1
+
+            # ---------------
+            # RUN VAL STEP
+            # ---------------
+            is_val_check_batch = (batch_nb + 1) % self.val_check_batch == 0
+            can_check_epoch = (self.current_epoch + 1) % self.check_val_every_n_epoch == 0
+            should_check_val = ((is_val_check_batch or early_stop_epoch) and can_check_epoch)
+
+            # fast_dev_run always forces val checking after train batch
+            if self.fast_dev_run or should_check_val:
+                self.run_evaluation(test=self.testing)
+
+            # when logs should be saved
+            should_save_log = (batch_nb + 1) % self.log_save_interval == 0 or early_stop_epoch
+            if should_save_log or self.fast_dev_run:
+                if self.proc_rank == 0 and self.logger is not None:
+                    self.logger.save()
+
+            # when metrics should be logged
+            should_log_metrics = batch_nb % self.row_log_interval == 0 or early_stop_epoch
+            if should_log_metrics or self.fast_dev_run:
+                # logs user requested information to logger
+                self.log_metrics(batch_step_metrics, grad_norm_dic)
+
+            self.global_step += 1
+            self.total_batch_nb += 1
+
+            # end epoch early
+            # stop when the flag is changed or we've gone past the amount
+            # requested in the batches
+            if early_stop_epoch or self.fast_dev_run:
+                break
+
+            # stop epoch if we limited nb batches
+            met_batch_limit = batch_nb >= self.nb_training_batches
+            if met_batch_limit:
+                break
+
+        # epoch end hook
+        if self.is_function_implemented('on_epoch_end'):
+            model = self.get_model()
+            model.on_epoch_end()
+
+    def run_training_batch(self, batch, batch_nb):
+        # track grad norms
+        grad_norm_dic = {}
+
+        # track all metrics for callbacks
+        all_callback_metrics = []
+
+        # track metrics to log
+        all_log_metrics = []
+
+        if batch is None:
+            return 0, grad_norm_dic
+
+        # hook
+        if self.is_function_implemented('on_batch_start'):
+            model_ref = self.get_model()
+            response = model_ref.on_batch_start(batch)
+
+            if response == -1:
+                return -1, grad_norm_dic
+
+        splits = [batch]
+        if self.truncated_bptt_steps is not None:
+            model_ref = self.get_model()
+            splits = model_ref.tbptt_split_batch(batch, self.truncated_bptt_steps)
+
+        self.hiddens = None
+        for split_nb, split_batch in enumerate(splits):
+            self.split_nb = split_nb
+
+            # call training_step once per optimizer
+            for opt_idx, optimizer in enumerate(self.optimizers):
+
+                # wrap the forward step in a closure so second order methods work
+                def optimizer_closure():
+                    # forward pass
+                    output = self.training_forward(
+                        split_batch, batch_nb, opt_idx, self.hiddens)
+
+                    closure_loss = output[0]
+                    progress_bar_metrics = output[1]
+                    log_metrics = output[2]
+                    callback_metrics = output[3]
+                    self.hiddens = output[4]
+
+                    # accumulate loss
+                    # (if accumulate_grad_batches = 1 no effect)
+                    closure_loss = closure_loss / self.accumulate_grad_batches
+
+                    # backward pass
+                    model_ref = self.get_model()
+                    model_ref.backward(self.use_amp, closure_loss, optimizer)
+
+                    # track metrics for callbacks
+                    all_callback_metrics.append(callback_metrics)
+
+                    # track progress bar metrics
+                    self.add_tqdm_metrics(progress_bar_metrics)
+                    all_log_metrics.append(log_metrics)
+
+                    # insert after step hook
+                    if self.is_function_implemented('on_after_backward'):
+                        model_ref = self.get_model()
+                        model_ref.on_after_backward()
+
+                    return closure_loss
+
+                # calculate loss
+                loss = optimizer_closure()
+
+                # nan grads
+                if self.print_nan_grads:
+                    self.print_nan_gradients()
+
+                # track total loss for logging (avoid mem leaks)
+                self.batch_loss_value += loss.item()
+
+                # gradient update with accumulated gradients
+                if (self.batch_nb + 1) % self.accumulate_grad_batches == 0:
+
+                    # track gradient norms when requested
+                    if batch_nb % self.row_log_interval == 0:
+                        if self.track_grad_norm > 0:
+                            model = self.get_model()
+                            grad_norm_dic = model.grad_norm(
+                                self.track_grad_norm)
+
+                    # clip gradients
+                    self.clip_gradients()
+
+                    # calls .step(), .zero_grad()
+                    # override function to modify this behavior
+                    model = self.get_model()
+                    model.optimizer_step(self.current_epoch, batch_nb,
+                                         optimizer, opt_idx, optimizer_closure)
+
+                    # calculate running loss for display
+                    self.running_loss.append(self.batch_loss_value)
+                    self.batch_loss_value = 0
+                    self.avg_loss = np.mean(self.running_loss[-100:])
+
+        # activate batch end hook
+        if self.is_function_implemented('on_batch_end'):
+            model = self.get_model()
+            model.on_batch_end()
+
+        # update progress bar
+        self.main_progress_bar.update(1)
+        self.main_progress_bar.set_postfix(**self.training_tqdm_dict)
+
+        # collapse all metrics into one dict
+        all_log_metrics = {k: v for d in all_log_metrics for k, v in d.items()}
+
+        # track all metrics for callbacks
+        self.callback_metrics = {k: v for d in all_callback_metrics for k, v in d.items()}
+
+        return 0, grad_norm_dic, all_log_metrics
+
+    def training_forward(self, batch, batch_nb, opt_idx, hiddens):
+        """
+        Handle forward for each training case (distributed, single gpu, etc...)
+        :param batch:
+        :param batch_nb:
+        :return:
+        """
+        # ---------------
+        # FORWARD
+        # ---------------
+        # enable not needing to add opt_idx to training_step
+        args = [batch, batch_nb]
+        if len(self.optimizers) > 1:
+            args.append(opt_idx)
+
+        # pass hiddens if using tbptt
+        if self.truncated_bptt_steps is not None:
+            args.append(hiddens)
+
+        # distributed forward
+        if self.use_ddp or self.use_ddp2 or self.use_dp:
+            output = self.model(*args)
+
+        # single GPU forward
+        elif self.single_gpu:
+            gpu_id = 0
+            if type(self.data_parallel_device_ids) is list:
+                gpu_id = self.data_parallel_device_ids[0]
+            batch = self.transfer_batch_to_gpu(batch, gpu_id)
+            args[0] = batch
+            output = self.model.training_step(*args)
+
+        # CPU forward
+        else:
+            output = self.model.training_step(*args)
+
+        # allow any mode to define training_end
+        if self.is_overriden('training_end'):
+            model_ref = self.get_model()
+            output = model_ref.training_end(output)
+
+        # format and reduce outputs accordingly
+        output = self.process_output(output, train=True)
+
+        return output

pytorch_lightning/trainer/trainer.py

@@ -0,0 +1,478 @@
+"""
+The trainer handles all the logic for running a val loop, training loop, distributing, etc.. .
+"""
+
+import os
+import warnings
+import logging
+
+import torch
+import torch.distributed as dist
+import torch.multiprocessing as mp
+import tqdm
+from torch.optim.optimizer import Optimizer
+
+from pytorch_lightning.trainer.amp_mixin import TrainerAMPMixin
+from pytorch_lightning.trainer.callback_config_mixin import TrainerCallbackConfigMixin
+from pytorch_lightning.trainer.data_loading_mixin import TrainerDataLoadingMixin
+from pytorch_lightning.trainer.ddp_mixin import TrainerDDPMixin
+from pytorch_lightning.trainer.dp_mixin import TrainerDPMixin
+from pytorch_lightning.trainer.dp_mixin import (
+    parse_gpu_ids,
+    determine_root_gpu_device
+)
+from pytorch_lightning.trainer.evaluation_loop_mixin import TrainerEvaluationLoopMixin
+from pytorch_lightning.trainer.logging_mixin import TrainerLoggingMixin
+from pytorch_lightning.trainer.model_hooks_mixin import TrainerModelHooksMixin
+from pytorch_lightning.trainer.train_loop_mixin import TrainerTrainLoopMixin
+from pytorch_lightning.trainer.trainer_io import TrainerIOMixin
+from pytorch_lightning.trainer.training_tricks_mixin import TrainerTrainingTricksMixin
+from pytorch_lightning.utilities.debugging import MisconfigurationException
+
+try:
+    from apex import amp
+
+    APEX_AVAILABLE = True
+except ImportError:
+    APEX_AVAILABLE = False
+
+
+class Trainer(TrainerIOMixin,
+              TrainerDDPMixin,
+              TrainerDPMixin,
+              TrainerDataLoadingMixin,
+              TrainerAMPMixin,
+              TrainerEvaluationLoopMixin,
+              TrainerTrainLoopMixin,
+              TrainerLoggingMixin,
+              TrainerTrainingTricksMixin,
+              TrainerCallbackConfigMixin,
+              TrainerModelHooksMixin):
+
+    def __init__(self,
+                 logger=True,
+                 checkpoint_callback=True,
+                 early_stop_callback=True,
+                 default_save_path=None,
+                 gradient_clip_val=0,
+                 gradient_clip=None,  # backward compatible
+                 process_position=0,
+                 nb_gpu_nodes=1,
+                 gpus=None,
+                 log_gpu_memory=None,
+                 show_progress_bar=True,
+                 overfit_pct=0.0,
+                 track_grad_norm=-1,
+                 check_val_every_n_epoch=1,
+                 fast_dev_run=False,
+                 accumulate_grad_batches=1,
+                 max_nb_epochs=1000,
+                 min_nb_epochs=1,
+                 train_percent_check=1.0,
+                 val_percent_check=1.0,
+                 test_percent_check=1.0,
+                 val_check_interval=1.0,
+                 log_save_interval=100,
+                 row_log_interval=10,
+                 add_row_log_interval=None,  # backward compatible
+                 distributed_backend=None,
+                 use_amp=False,
+                 print_nan_grads=False,
+                 weights_summary='full',
+                 weights_save_path=None,
+                 amp_level='O1',
+                 nb_sanity_val_steps=5,
+                 truncated_bptt_steps=None):
+        """
+
+        :param logger: Logger for experiment tracking
+        :param checkpoint_callback: Callback for checkpointing
+        :param early_stop_callback: Callback for early stopping
+        :param default_save_path: Default path for logs+weights if no logger/ckpt_callback passed
+        :param gradient_clip_val: int. 0 means don't clip.
+        :param gradient_clip: int. 0 means don't clip. Deprecated.
+        :param process_position: shown in the tqdm bar
+        :param nb_gpu_nodes: number of GPU nodes
+        :param gpus: int. (ie: 2 gpus) OR list to specify which GPUs [0, 1] OR '0,1'
+            OR '-1' / -1 to use all available gpus
+        :param log_gpu_memory: str. None, 'min_max', 'all'
+        :param show_progress_bar: Bool. If true shows tqdm bar
+        :param overfit_pct: float. uses this much of all datasets
+        :param track_grad_norm: int. -1 no tracking. Otherwise tracks that norm
+        :param check_val_every_n_epoch: int. check val every n train epochs
+        :param fast_dev_run: Bool. runs full iteration over everything to find bugs
+        :param accumulate_grad_batches: int. Accumulates grads every k batches
+        :param max_nb_epochs: int.
+        :param min_nb_epochs: int.
+        :param train_percent_check: int. How much of train set to check
+        :param val_percent_check: int. How much of val set to check
+        :param test_percent_check: int. How much of test set to check
+        :param val_check_interval: float/int. If float, % of tng epoch. If int, check every n batch
+        :param log_save_interval: int. Writes logs to disk this often
+        :param row_log_interval: int. How often to add logging rows
+        :param add_row_log_interval: int. How often to add logging rows. Deprecated.
+        :param distributed_backend: str. Options: 'dp', 'ddp', 'ddp2'.
+        :param use_amp: Bool. If true uses apex for 16bit precision
+        :param print_nan_grads: Bool. Prints nan gradients
+        :param weights_summary: str. Options: 'full', 'top', None to not print.
+        :param weights_save_path: Bool. Where to save weights if on cluster
+        :param amp_level: str. Check nvidia docs for level
+        :param nb_sanity_val_steps: int. How many val steps before a full train loop.
+        :param truncated_bptt_steps: int. Enables multiple backward passes for each batch.
+        """
+        # Transfer params
+        self.nb_gpu_nodes = nb_gpu_nodes
+        self.log_gpu_memory = log_gpu_memory
+        if not (gradient_clip is None):
+            # Backward compatibility
+            warnings.warn("gradient_clip has renamed to gradient_clip_val since v0.5.0",
+                          DeprecationWarning)
+            gradient_clip_val = gradient_clip
+        self.gradient_clip_val = gradient_clip_val
+        self.check_val_every_n_epoch = check_val_every_n_epoch
+        self.track_grad_norm = track_grad_norm
+        self.on_gpu = gpus is not None and torch.cuda.is_available()
+        self.process_position = process_position
+        self.weights_summary = weights_summary
+        self.max_nb_epochs = max_nb_epochs
+        self.min_nb_epochs = min_nb_epochs
+        self.nb_sanity_val_steps = nb_sanity_val_steps
+        self.print_nan_grads = print_nan_grads
+        self.truncated_bptt_steps = truncated_bptt_steps
+        self.shown_warnings = set()
+
+        self.fast_dev_run = fast_dev_run
+        if self.fast_dev_run:
+            self.nb_sanity_val_steps = 1
+            self.max_nb_epochs = 1
+            m = '''
+            Running in fast_dev_run mode: will run a full train,
+            val loop using a single batch
+            '''
+            logging.info(m)
+
+        # set default save path if user didn't provide one
+        self.default_save_path = default_save_path
+        if self.default_save_path is None:
+            self.default_save_path = os.getcwd()
+
+        # training bookeeping
+        self.total_batch_nb = 0
+        self.running_loss = []
+        self.avg_loss = 0
+        self.batch_nb = 0
+        self.tqdm_metrics = {}
+        self.callback_metrics = {}
+        self.nb_val_batches = 0
+        self.nb_training_batches = 0
+        self.nb_test_batches = 0
+        self.get_train_dataloader = None
+        self.get_test_dataloaders = None
+        self.get_val_dataloaders = None
+        self.is_iterable_train_dataloader = False
+
+        # training state
+        self.model = None
+        self.testing = False
+        self.lr_schedulers = []
+        self.optimizers = None
+        self.global_step = 0
+        self.current_epoch = 0
+        self.total_batches = 0
+
+        # configure early stop callback
+        # creates a default one if none passed in
+        self.early_stop_callback = None
+        self.configure_early_stopping(early_stop_callback, logger)
+
+        # configure checkpoint callback
+        self.checkpoint_callback = checkpoint_callback
+        self.weights_save_path = weights_save_path
+
+        # accumulated grads
+        self.configure_accumulated_gradients(accumulate_grad_batches)
+
+        # allow int, string and gpu list
+        self.data_parallel_device_ids = parse_gpu_ids(gpus)
+        self.root_gpu = determine_root_gpu_device(self.data_parallel_device_ids)
+
+        # distributed backend choice
+        self.use_ddp = False
+        self.use_ddp2 = False
+        self.use_dp = False
+        self.single_gpu = False
+        self.distributed_backend = distributed_backend
+        self.set_distributed_mode(distributed_backend, nb_gpu_nodes)
+
+        # init flags for SLURM+ddp to work
+        self.proc_rank = 0
+        self.world_size = 1
+        self.node_rank = 0
+        self.configure_slurm_ddp(nb_gpu_nodes)
+
+        # nvidia setup
+        self.set_nvidia_flags(self.is_slurm_managing_tasks, self.data_parallel_device_ids)
+
+        # can't init progress bar here because starting a new process
+        # means the progress_bar won't survive pickling
+        self.show_progress_bar = show_progress_bar
+
+        # logging
+        self.log_save_interval = log_save_interval
+        self.val_check_interval = val_check_interval
+        if not (add_row_log_interval is None):
+            # backward compatibility
+            warnings.warn("gradient_clip has renamed to gradient_clip_val since v0.5.0",
+                          DeprecationWarning)
+            row_log_interval = add_row_log_interval
+        self.row_log_interval = row_log_interval
+
+        # how much of the data to use
+        self.determine_data_use_amount(train_percent_check, val_percent_check,
+                                       test_percent_check, overfit_pct)
+
+        # 16 bit mixed precision training using apex
+        self.amp_level = amp_level
+        self.init_amp(use_amp)
+
+        # set logging options
+        logging.basicConfig(level=logging.INFO)
+
+    @property
+    def slurm_job_id(self):
+        try:
+            job_id = os.environ['SLURM_JOB_ID']
+            job_id = int(job_id)
+        except Exception as e:
+            job_id = None
+        return job_id
+
+    def __parse_gpu_ids(self, gpus):
+        """
+        :param gpus: Int, string or list of ids
+        :return:
+        """
+        # if gpus = -1 then use all available devices
+        # otherwise, split the string using commas
+        if gpus is not None:
+            if type(gpus) is list:
+                gpus = gpus
+            elif type(gpus) is str:
+                if gpus == '-1':
+                    gpus = list(range(0, torch.cuda.device_count()))
+                else:
+                    gpus = [int(x.strip()) for x in gpus.split(',')]
+            elif type(gpus) is int:
+                gpus = gpus
+            else:
+                raise Exception('gpus has to be a string, int or list of ints')
+
+        return gpus
+
+    def __set_root_gpu(self, gpus):
+        if gpus is None:
+            return None
+
+        # set root gpu
+        root_gpu = 0
+        if type(gpus) is list:
+            root_gpu = gpus[0]
+
+        return root_gpu
+
+    @property
+    def num_gpus(self):
+        gpus = self.data_parallel_device_ids
+        if gpus is None:
+            return 0
+        else:
+            return len(gpus)
+
+    @property
+    def data_parallel(self):
+        return self.use_dp or self.use_ddp or self.use_ddp2
+
+    @property
+    def training_tqdm_dict(self):
+        """
+        Read-only for tqdm metrics
+        :return:
+        """
+        tqdm_dict = {
+            'loss': '{0:.3f}'.format(self.avg_loss),
+            'batch_nb': '{}'.format(self.batch_nb),
+        }
+
+        if self.truncated_bptt_steps is not None:
+            tqdm_dict['split_nb'] = self.split_nb
+
+        if self.logger is not None and self.logger.version is not None:
+            tqdm_dict['v_nb'] = self.logger.version
+
+        tqdm_dict.update(self.tqdm_metrics)
+
+        if self.on_gpu:
+            tqdm_dict['gpu'] = '{}'.format(torch.cuda.current_device())
+
+        return tqdm_dict
+
+    @property
+    def tng_tqdm_dic(self):
+        """
+        * Deprecated in v0.5.0. use training_tqdm_dict instead. *
+        :return:
+        """
+        warnings.warn("tng_tqdm_dict has renamed to training_tqdm_dict since v0.5.0",
+                      DeprecationWarning)
+        return self.training_tqdm_dict
+
+    # -----------------------------
+    # MODEL TRAINING
+    # -----------------------------
+    def fit(self, model):
+        # when using multi-node or DDP within a node start each module in a separate process
+        if self.use_ddp2:
+            task = int(os.environ['SLURM_LOCALID'])
+            self.ddp_train(task, model)
+
+        elif self.use_ddp:
+            if self.is_slurm_managing_tasks:
+                task = int(os.environ['SLURM_LOCALID'])
+                self.ddp_train(task, model)
+            else:
+                mp.spawn(self.ddp_train, nprocs=self.num_gpus, args=(model,))
+
+        # 1 gpu or dp option triggers training using DP module
+        # easier to avoid NCCL issues
+        elif self.use_dp:
+            self.dp_train(model)
+
+        elif self.single_gpu:
+            self.single_gpu_train(model)
+
+        # ON CPU
+        else:
+            # run through amp wrapper
+            if self.use_amp:
+                raise MisconfigurationException('amp + cpu is not supported.'
+                                                ' Please use a GPU option')
+
+            # CHOOSE OPTIMIZER
+            # allow for lr schedulers as well
+            self.optimizers, self.lr_schedulers = self.init_optimizers(model.configure_optimizers())
+
+            self.run_pretrain_routine(model)
+
+        # return 1 when finished
+        # used for testing or when we need to know that training succeeded
+        return 1
+
+    def init_optimizers(self, optimizers):
+
+        # single optimizer
+        if isinstance(optimizers, Optimizer):
+            return [optimizers], []
+
+        # two lists
+        elif len(optimizers) == 2 and isinstance(optimizers[0], list):
+            optimizers, lr_schedulers = optimizers
+            return optimizers, lr_schedulers
+
+        # single list or tuple
+        elif isinstance(optimizers, list) or isinstance(optimizers, tuple):
+            return optimizers, []
+
+    def run_pretrain_routine(self, model):
+        """
+        Sanity check a few things before starting actual training
+        :param model:
+        :return:
+        """
+        ref_model = model
+        if self.data_parallel:
+            ref_model = model.module
+
+        # give model convenience properties
+        ref_model.trainer = self
+
+        # set local properties on the model
+        self.copy_trainer_model_properties(ref_model)
+
+        # link up experiment object
+        if self.logger is not None:
+            ref_model.logger = self.logger
+
+            # save exp to get started
+            if hasattr(ref_model, "hparams"):
+                self.logger.log_hyperparams(ref_model.hparams)
+
+            self.logger.save()
+
+        if self.use_ddp or self.use_ddp2:
+            dist.barrier()
+
+        # set up checkpoint callback
+        self.configure_checkpoint_callback()
+
+        # register auto-resubmit when on SLURM
+        self.register_slurm_signal_handlers()
+
+        # transfer data loaders from model
+        self.get_dataloaders(ref_model)
+
+        # print model summary
+        if self.proc_rank == 0 and self.weights_summary is not None:
+            if self.weights_summary in ['full', 'top']:
+                ref_model.summarize(mode=self.weights_summary)
+            else:
+                m = "weights_summary can be None, 'full' or 'top'"
+                raise MisconfigurationException(m)
+
+        # track model now.
+        # if cluster resets state, the model will update with the saved weights
+        self.model = model
+
+        # restore training and model before hpc call
+        self.restore_weights(model)
+
+        # when testing requested only run test and return
+        if self.testing:
+            self.run_evaluation(test=True)
+            return
+
+        # run tiny validation (if validation defined)
+        # to make sure program won't crash during val
+        ref_model.on_sanity_check_start()
+        if self.get_val_dataloaders() is not None and self.nb_sanity_val_steps > 0:
+            # init progress bars for validation sanity check
+            pbar = tqdm.tqdm(desc='Validation sanity check', total=self.nb_sanity_val_steps,
+                             leave=False, position=2 * self.process_position,
+                             disable=not self.show_progress_bar, dynamic_ncols=True, unit='batch')
+            self.main_progress_bar = pbar
+            # dummy validation progress bar
+            self.val_progress_bar = tqdm.tqdm(disable=True)
+
+            self.evaluate(model, self.get_val_dataloaders(), self.nb_sanity_val_steps, self.testing)
+
+            # close progress bars
+            self.main_progress_bar.close()
+            self.val_progress_bar.close()
+
+        # init progress bar
+        pbar = tqdm.tqdm(leave=True, position=2 * self.process_position,
+                         disable=not self.show_progress_bar, dynamic_ncols=True, unit='batch')
+        self.main_progress_bar = pbar
+
+        # clear cache before training
+        if self.on_gpu:
+            torch.cuda.empty_cache()
+
+        # CORE TRAINING LOOP
+        self.train()
+
+    def test(self, model=None):
+        self.testing = True
+        if model is not None:
+            self.fit(model)
+        else:
+            self.run_evaluation(test=True)

pytorch_lightning/trainer/trainer_io.py

@@ -0,0 +1,376 @@
+import os
+import re
+import signal
+import warnings
+from subprocess import call
+import logging
+
+import torch
+import torch.distributed as dist
+
+from pytorch_lightning.pt_overrides.override_data_parallel import (
+    LightningDistributedDataParallel, LightningDataParallel)
+
+
+class TrainerIOMixin(object):
+
+    def get_model(self):
+        is_dp_module = isinstance(self.model, (LightningDistributedDataParallel,
+                                               LightningDataParallel))
+        model = self.model.module if is_dp_module else self.model
+        return model
+
+    # --------------------
+    # CHECK-POINTING
+    # --------------------
+    def restore_weights(self, model):
+        """
+        To restore weights we have two cases.
+        First, attempt to restore hpc weights. If successful, don't restore
+        other weights.
+
+        Otherwise, try to restore actual weights
+        :param model:
+        :return:
+        """
+        # clear cache before restore
+        if self.on_gpu:
+            torch.cuda.empty_cache()
+
+        # if script called from hpc resubmit, load weights
+        did_restore_hpc_weights = self.restore_hpc_weights_if_needed(model)
+
+        # clear cache after restore
+        if self.on_gpu:
+            torch.cuda.empty_cache()
+
+        if not did_restore_hpc_weights:
+            # restore weights if same exp version
+            self.restore_state_if_checkpoint_exists(model)
+
+        # wait for all models to restore weights
+        if self.use_ddp or self.use_ddp2:
+            # wait for all processes to catch up
+            dist.barrier()
+
+        # clear cache after restore
+        if self.on_gpu:
+            torch.cuda.empty_cache()
+
+    def restore_state_if_checkpoint_exists(self, model):
+        did_restore = False
+
+        # do nothing if there's not dir or callback
+        no_ckpt_callback = (self.checkpoint_callback is None) or (not self.checkpoint_callback)
+        if no_ckpt_callback or not os.path.exists(self.checkpoint_callback.filepath):
+            return did_restore
+
+        # restore trainer state and model if there is a weight for this experiment
+        last_epoch = -1
+        last_ckpt_name = None
+
+        # find last epoch
+        checkpoints = os.listdir(self.checkpoint_callback.filepath)
+        for name in checkpoints:
+            # ignore hpc ckpts
+            if 'hpc_' in name:
+                continue
+
+            if '.ckpt' in name:
+                epoch = name.split('epoch_')[1]
+                epoch = int(re.sub('[^0-9]', '', epoch))
+
+                if epoch > last_epoch:
+                    last_epoch = epoch
+                    last_ckpt_name = name
+
+        # restore last checkpoint
+        if last_ckpt_name is not None:
+            last_ckpt_path = os.path.join(self.checkpoint_callback.filepath, last_ckpt_name)
+            self.restore(last_ckpt_path, self.on_gpu)
+            logging.info(f'model and trainer restored from checkpoint: {last_ckpt_path}')
+            did_restore = True
+
+        return did_restore
+
+    # --------------------
+    # HPC SIGNAL HANDLING
+    # --------------------
+    def register_slurm_signal_handlers(self):
+        # see if we're using slurm (not interactive)
+        on_slurm = False
+        try:
+            job_name = os.environ['SLURM_JOB_NAME']
+            if job_name != 'bash':
+                on_slurm = True
+        except Exception as e:
+            pass
+
+        if on_slurm:
+            logging.info('set slurm handle signals')
+            signal.signal(signal.SIGUSR1, self.sig_handler)
+            signal.signal(signal.SIGTERM, self.term_handler)
+
+    def sig_handler(self, signum, frame):
+        if self.proc_rank == 0:
+            # save weights
+            logging.info('handling SIGUSR1')
+            self.hpc_save(self.weights_save_path, self.logger)
+
+            # find job id
+            job_id = os.environ['SLURM_JOB_ID']
+            cmd = 'scontrol requeue {}'.format(job_id)
+
+            # requeue job
+            logging.info('\nrequeing job {job_id}...')
+            result = call(cmd, shell=True)
+
+            # print result text
+            if result == 0:
+                logging.info('requeued exp {job_id}')
+            else:
+                logging.info('requeue failed...')
+
+            # close experiment to avoid issues
+            self.logger.close()
+
+    def term_handler(self, signum, frame):
+        # save
+        logging.info("bypassing sigterm")
+
+    # --------------------
+    # MODEL SAVE CHECKPOINT
+    # --------------------
+    def save_checkpoint(self, filepath):
+        checkpoint = self.dump_checkpoint()
+
+        # do the actual save
+        try:
+            torch.save(checkpoint, filepath)
+        except AttributeError:
+            if 'hparams' in checkpoint:
+                del checkpoint['hparams']
+
+            torch.save(checkpoint, filepath)
+
+    def restore(self, checkpoint_path, on_gpu):
+
+        # if on_gpu:
+        #     checkpoint = torch.load(checkpoint_path)
+        # else:
+        # load on CPU first
+        checkpoint = torch.load(checkpoint_path, map_location=lambda storage, loc: storage)
+
+        # load model state
+        model = self.get_model()
+
+        # load the state_dict on the model automatically
+        model.load_state_dict(checkpoint['state_dict'])
+        if on_gpu:
+            model.cuda(self.root_gpu)
+
+        # load training state (affects trainer only)
+        self.restore_training_state(checkpoint)
+
+    def dump_checkpoint(self):
+
+        checkpoint = {
+            'epoch': self.current_epoch,
+            'global_step': self.global_step
+        }
+
+        if self.checkpoint_callback is not None and self.checkpoint_callback is not False:
+            checkpoint['checkpoint_callback_best'] = self.checkpoint_callback.best
+
+        if self.early_stop_callback is not None and self.checkpoint_callback is not False:
+            checkpoint['early_stop_callback_wait'] = self.early_stop_callback.wait
+            checkpoint['early_stop_callback_patience'] = self.early_stop_callback.patience
+
+        # save optimizers
+        optimizer_states = []
+        for i, optimizer in enumerate(self.optimizers):
+            optimizer_states.append(optimizer.state_dict())
+
+        checkpoint['optimizer_states'] = optimizer_states
+
+        # save lr schedulers
+        lr_schedulers = []
+        for i, scheduler in enumerate(self.lr_schedulers):
+            lr_schedulers.append(scheduler.state_dict())
+
+        checkpoint['lr_schedulers'] = lr_schedulers
+
+        # add the hparams and state_dict from the model
+        model = self.get_model()
+        checkpoint['state_dict'] = model.state_dict()
+        if hasattr(model, "hparams"):
+            checkpoint['hparams'] = vars(model.hparams)
+        else:
+            warnings.warn(
+                "Did not find hyperparameters at model.hparams. Saving checkpoint without"
+                " hyperparameters"
+            )
+
+        # give the model a chance to add a few things
+        model.on_save_checkpoint(checkpoint)
+
+        return checkpoint
+
+    # --------------------
+    # HPC IO
+    # --------------------
+    def restore_hpc_weights_if_needed(self, model):
+        """
+        If there is a set of hpc weights, use as signal to restore model
+        :param model:
+        :return:
+        """
+        did_restore = False
+
+        # look for hpc weights
+        folderpath = self.weights_save_path
+        if os.path.exists(folderpath):
+            files = os.listdir(folderpath)
+            hpc_weight_paths = [x for x in files if 'hpc_ckpt' in x]
+
+            # if hpc weights exist restore model
+            if len(hpc_weight_paths) > 0:
+                self.hpc_load(folderpath, self.on_gpu)
+                did_restore = True
+        return did_restore
+
+    def restore_training_state(self, checkpoint):
+        """
+        Restore trainer state.
+        Model will get its change to update
+        :param checkpoint:
+        :return:
+        """
+        if self.checkpoint_callback is not None and self.checkpoint_callback is not False:
+            self.checkpoint_callback.best = checkpoint['checkpoint_callback_best']
+
+        if self.early_stop_callback is not None and self.early_stop_callback is not False:
+            self.early_stop_callback.wait = checkpoint['early_stop_callback_wait']
+            self.early_stop_callback.patience = checkpoint['early_stop_callback_patience']
+
+        self.global_step = checkpoint['global_step']
+        self.current_epoch = checkpoint['epoch']
+
+        # restore the optimizers
+        optimizer_states = checkpoint['optimizer_states']
+        for optimizer, opt_state in zip(self.optimizers, optimizer_states):
+            optimizer.load_state_dict(opt_state)
+
+            # move optimizer to GPU 1 weight at a time
+            # avoids OOM
+            if self.root_gpu is not None:
+                for state in optimizer.state.values():
+                    for k, v in state.items():
+                        if isinstance(v, torch.Tensor):
+                            state[k] = v.cuda(self.root_gpu)
+
+        # restore the lr schedulers
+        lr_schedulers = checkpoint['lr_schedulers']
+        for scheduler, lrs_state in zip(self.lr_schedulers, lr_schedulers):
+            scheduler.load_state_dict(lrs_state)
+
+    # ----------------------------------
+    # PRIVATE OPS
+    # ----------------------------------
+    def hpc_save(self, folderpath, logger):
+        # make sure the checkpoint folder exists
+        os.makedirs(folderpath, exist_ok=True)
+
+        # save logger to make sure we get all the metrics
+        logger.save()
+
+        ckpt_number = self.max_ckpt_in_folder(folderpath) + 1
+
+        if not os.path.exists(folderpath):
+            os.makedirs(folderpath, exist_ok=True)
+        filepath = '{}/hpc_ckpt_{}.ckpt'.format(folderpath, ckpt_number)
+
+        # give model a chance to do something on hpc_save
+        model = self.get_model()
+        checkpoint = self.dump_checkpoint()
+
+        model.on_hpc_save(checkpoint)
+
+        # do the actual save
+        # TODO: fix for anything with multiprocess DP, DDP, DDP2
+        try:
+            torch.save(checkpoint, filepath)
+        except AttributeError:
+            if 'hparams' in checkpoint:
+                del checkpoint['hparams']
+
+            torch.save(checkpoint, filepath)
+
+        return filepath
+
+    def hpc_load(self, folderpath, on_gpu):
+        filepath = '{}/hpc_ckpt_{}.ckpt'.format(folderpath, self.max_ckpt_in_folder(folderpath))
+
+        # load on CPU first
+        checkpoint = torch.load(filepath, map_location=lambda storage, loc: storage)
+
+        # load model state
+        model = self.get_model()
+
+        # load the state_dict on the model automatically
+        model.load_state_dict(checkpoint['state_dict'])
+
+        if self.root_gpu is not None:
+            model.cuda(self.root_gpu)
+
+        # load training state (affects trainer only)
+        self.restore_training_state(checkpoint)
+
+        # call model hook
+        model.on_hpc_load(checkpoint)
+
+        logging.info(f'restored hpc model from: {filepath}')
+
+    def max_ckpt_in_folder(self, path, name_key='ckpt_'):
+        files = os.listdir(path)
+        files = [x for x in files if name_key in x]
+        if len(files) == 0:
+            return 0
+
+        ckpt_vs = []
+        for name in files:
+            name = name.split(name_key)[-1]
+            name = re.sub('[^0-9]', '', name)
+            ckpt_vs.append(int(name))
+
+        return max(ckpt_vs)
+
+
+def load_hparams_from_tags_csv(tags_csv):
+    from argparse import Namespace
+    import pandas as pd
+
+    tags_df = pd.read_csv(tags_csv)
+    dic = tags_df.to_dict(orient='records')
+
+    ns_dict = {row['key']: convert(row['value']) for row in dic}
+
+    ns = Namespace(**ns_dict)
+    return ns
+
+
+def convert(val):
+    constructors = [int, float, str]
+
+    if type(val) is str:
+        if val.lower() == 'true':
+            return True
+        if val.lower() == 'false':
+            return False
+
+    for c in constructors:
+        try:
+            return c(val)
+        except ValueError:
+            pass
+    return val

pytorch_lightning/trainer/training_tricks_mixin.py

@@ -0,0 +1,28 @@
+import torch
+import logging
+from pytorch_lightning.callbacks import GradientAccumulationScheduler
+
+
+class TrainerTrainingTricksMixin(object):
+
+    def clip_gradients(self):
+        if self.gradient_clip_val > 0:
+            model = self.get_model()
+            torch.nn.utils.clip_grad_norm_(model.parameters(), self.gradient_clip_val)
+
+    def print_nan_gradients(self):
+        model = self.get_model()
+        for param in model.parameters():
+            if torch.isnan(param.grad.float()).any():
+                logging.info(param, param.grad)
+
+    def configure_accumulated_gradients(self, accumulate_grad_batches):
+        self.accumulate_grad_batches = None
+
+        if isinstance(accumulate_grad_batches, dict):
+            self.accumulation_scheduler = GradientAccumulationScheduler(accumulate_grad_batches)
+        elif isinstance(accumulate_grad_batches, int):
+            schedule = {1: accumulate_grad_batches}
+            self.accumulation_scheduler = GradientAccumulationScheduler(schedule)
+        else:
+            raise TypeError("Gradient accumulation supports only int and dict types")

pytorch_lightning/trainer_main.py

@@ -1,210 +0,0 @@
-import os
-import sys
-
-import torch
-import numpy as np
-from test_tube import HyperOptArgumentParser, Experiment, SlurmCluster
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.utils.arg_parse import add_default_args
-from time import sleep
-
-from pytorch_lightning.callbacks.pt_callbacks import EarlyStopping, ModelCheckpoint
-SEED = 2334
-torch.manual_seed(SEED)
-np.random.seed(SEED)
-
-# ---------------------
-# DEFINE MODEL HERE
-# ---------------------
-from pytorch_lightning.models.sample_model_template.model_template import ExampleModel1
-# ---------------------
-
-AVAILABLE_MODELS = {
-    'model_1': ExampleModel1
-}
-
-
-"""
-Allows training by using command line arguments
-
-Run by: 
-# TYPE YOUR RUN COMMAND HERE
-"""
-
-
-def main_local(hparams):
-    main(hparams, None, None)
-
-
-def main(hparams, cluster, results_dict):
-    """
-    Main training routine specific for this project
-    :param hparams:
-    :return:
-    """
-    on_gpu = torch.cuda.is_available()
-    if hparams.disable_cuda:
-        on_gpu = False
-
-    device = 'cuda' if on_gpu else 'cpu'
-    hparams.__setattr__('device', device)
-    hparams.__setattr__('on_gpu', on_gpu)
-    hparams.__setattr__('nb_gpus', torch.cuda.device_count())
-    hparams.__setattr__('inference_mode', hparams.model_load_weights_path is not None)
-
-    # init experiment
-    exp = Experiment(
-        name=hparams.tt_name,
-        debug=hparams.debug,
-        save_dir=hparams.tt_save_path,
-        version=hparams.hpc_exp_number,
-        autosave=False,
-        description=hparams.tt_description
-    )
-
-    exp.argparse(hparams)
-    exp.save()
-
-    # build model
-    print('loading model...')
-    model = TRAINING_MODEL(hparams)
-    print('model built')
-
-    # callbacks
-    early_stop = EarlyStopping(
-        monitor=hparams.early_stop_metric,
-        patience=hparams.early_stop_patience,
-        verbose=True,
-        mode=hparams.early_stop_mode
-    )
-
-    model_save_path = '{}/{}/{}'.format(hparams.model_save_path, exp.name, exp.version)
-    checkpoint = ModelCheckpoint(
-        filepath=model_save_path,
-        save_function=None,
-        save_best_only=True,
-        verbose=True,
-        monitor=hparams.model_save_monitor_value,
-        mode=hparams.model_save_monitor_mode
-    )
-
-    # configure trainer
-    trainer = Trainer(
-        experiment=exp,
-        on_gpu=on_gpu,
-        cluster=cluster,
-        progress_bar=hparams.enable_tqdm,
-        overfit_pct=hparams.overfit,
-        track_grad_norm=hparams.track_grad_norm,
-        fast_dev_run=hparams.fast_dev_run,
-        check_val_every_n_epoch=hparams.check_val_every_n_epoch,
-        accumulate_grad_batches=hparams.accumulate_grad_batches,
-        process_position=process_position,
-        current_gpu_name=current_gpu,
-        checkpoint_callback=checkpoint,
-        early_stop_callback=early_stop,
-        enable_early_stop=hparams.enable_early_stop,
-        max_nb_epochs=hparams.max_nb_epochs,
-        min_nb_epochs=hparams.min_nb_epochs,
-        train_percent_check=hparams.train_percent_check,
-        val_percent_check=hparams.val_percent_check,
-        test_percent_check=hparams.test_percent_check,
-        val_check_interval=hparams.val_check_interval,
-        log_save_interval=hparams.log_save_interval,
-        add_log_row_interval=hparams.add_log_row_interval,
-        lr_scheduler_milestones=hparams.lr_scheduler_milestones
-    )
-
-    # train model
-    trainer.fit(model)
-
-
-def get_default_parser(strategy, root_dir):
-
-    possible_model_names = list(AVAILABLE_MODELS.keys())
-    parser = HyperOptArgumentParser(strategy=strategy, add_help=False)
-    add_default_args(parser, root_dir, possible_model_names, SEED)
-    return parser
-
-
-def get_model_name(args):
-    for i, arg in enumerate(args):
-        if 'model_name' in arg:
-            return args[i+1]
-
-
-def optimize_on_cluster(hyperparams):
-    # enable cluster training
-    cluster = SlurmCluster(
-        hyperparam_optimizer=hyperparams,
-        log_path=hyperparams.tt_save_path,
-        test_tube_exp_name=hyperparams.tt_name
-    )
-
-    # email for cluster coms
-    cluster.notify_job_status(email='add_email_here', on_done=True, on_fail=True)
-
-    # configure cluster
-    cluster.per_experiment_nb_gpus = hyperparams.per_experiment_nb_gpus
-    cluster.job_time = '48:00:00'
-    cluster.gpu_type = '1080ti'
-    cluster.memory_mb_per_node = 48000
-
-    # any modules for code to run in env
-    cluster.add_command('source activate pytorch_lightning')
-
-    # name of exp
-    job_display_name = hyperparams.tt_name.split('_')[0]
-    job_display_name = job_display_name[0:3]
-
-    # run hopt
-    print('submitting jobs...')
-    cluster.optimize_parallel_cluster_gpu(
-        main,
-        nb_trials=hyperparams.nb_hopt_trials,
-        job_name=job_display_name
-    )
-
-
-if __name__ == '__main__':
-
-    model_name = get_model_name(sys.argv)
-
-    # use default args
-    root_dir = os.path.split(os.path.dirname(sys.modules['__main__'].__file__))[0]
-    parent_parser = get_default_parser(strategy='random_search', root_dir=root_dir)
-
-    # allow model to overwrite or extend args
-    TRAINING_MODEL = AVAILABLE_MODELS[model_name]
-    parser = TRAINING_MODEL.add_model_specific_args(parent_parser)
-    parser.json_config('-c', '--config', default=root_dir + '/run_configs/local.json')
-    hyperparams = parser.parse_args()
-
-    # format GPU layout
-    os.environ["CUDA_DEVICE_ORDER"] = "PCI_BUS_ID"
-    gpu_ids = hyperparams.gpus.split(';')
-
-    # RUN TRAINING
-    if hyperparams.on_cluster:
-        print('RUNNING ON SLURM CLUSTER')
-        os.environ["CUDA_VISIBLE_DEVICES"] = ','.join(gpu_ids)
-        optimize_on_cluster(hyperparams)
-
-    elif hyperparams.single_run_gpu:
-        print(f'RUNNING 1 TRIAL ON GPU. gpu: {gpu_ids[0]}')
-        os.environ["CUDA_VISIBLE_DEVICES"] = gpu_ids[0]
-        main(hyperparams, None, None)
-
-    elif hyperparams.local or hyperparams.single_run:
-        os.environ["CUDA_VISIBLE_DEVICES"] = '0'
-        print('RUNNING LOCALLY')
-        main(hyperparams, None, None)
-
-    else:
-        print(f'RUNNING MULTI GPU. GPU ids: {gpu_ids}')
-        hyperparams.optimize_parallel_gpu(
-            main_local,
-            gpu_ids=gpu_ids,
-            nb_trials=hyperparams.nb_hopt_trials,
-            nb_workers=len(gpu_ids)
-        )

pytorch_lightning/utilities/arg_parse.py

@@ -1,31 +1,47 @@
-import pdb
+"""
+List of default args which mught be useful for all the available flags
+Might need to update with the new flags
+"""
+
+import os
+
 
 def add_default_args(parser, root_dir, rand_seed=None, possible_model_names=None):
-
-    # tng, test, val check intervals
-    parser.add_argument('--eval_test_set', dest='eval_test_set', action='store_true', help='true = run test set also')
-    parser.add_argument('--check_val_every_n_epoch', default=1, type=int, help='check val every n epochs')
+    # training, test, val check intervals
+    parser.add_argument('--eval_test_set', dest='eval_test_set', action='store_true',
+                        help='true = run test set also')
+    parser.add_argument('--check_val_every_n_epoch', default=1, type=int,
+                        help='check val every n epochs')
     parser.opt_list('--accumulate_grad_batches', default=1, type=int, tunable=False,
-                    help='accumulates gradients k times before applying update. Simulates huge batch size')
+                    help='accumulates gradients k times before applying update.'
+                         ' Simulates huge batch size')
     parser.add_argument('--max_nb_epochs', default=200, type=int, help='cap epochs')
     parser.add_argument('--min_nb_epochs', default=2, type=int, help='min epochs')
-    parser.add_argument('--train_percent_check', default=1.0, type=float, help='how much of tng set to check')
-    parser.add_argument('--val_percent_check', default=1.0, type=float, help='how much of val set to check')
-    parser.add_argument('--test_percent_check', default=1.0, type=float, help='how much of test set to check')
+    parser.add_argument('--train_percent_check', default=1.0, type=float,
+                        help='how much of training set to check')
+    parser.add_argument('--val_percent_check', default=1.0, type=float,
+                        help='how much of val set to check')
+    parser.add_argument('--test_percent_check', default=1.0, type=float,
+                        help='how much of test set to check')
 
-    parser.add_argument('--val_check_interval', default=0.95, type=float, help='how much within 1 epoch to check val')
-    parser.add_argument('--log_save_interval', default=100, type=int, help='how many batches between log saves')
-    parser.add_argument('--add_log_row_interval', default=100, type=int, help='add log every k batches')
+    parser.add_argument('--val_check_interval', default=0.95, type=float,
+                        help='how much within 1 epoch to check val')
+    parser.add_argument('--log_save_interval', default=100, type=int,
+                        help='how many batches between log saves')
+    parser.add_argument('--row_log_interval', default=100, type=int,
+                        help='add log every k batches')
 
     # early stopping
     parser.add_argument('--disable_early_stop', dest='enable_early_stop', action='store_false')
     parser.add_argument('--early_stop_metric', default='val_acc', type=str)
     parser.add_argument('--early_stop_mode', default='min', type=str)
-    parser.add_argument('--early_stop_patience', default=3, type=int, help='number of epochs until stop')
+    parser.add_argument('--early_stop_patience', default=3, type=int,
+                        help='number of epochs until stop')
 
     # gradient handling
-    parser.add_argument('--gradient_clip', default=-1, type=int)
-    parser.add_argument('--track_grad_norm', default=-1, type=int, help='if > 0, will track this grad norm')
+    parser.add_argument('--gradient_clip_val', default=-1, type=int)
+    parser.add_argument('--track_grad_norm', default=-1, type=int,
+                        help='if > 0, will track this grad norm')
 
     # model saving
     parser.add_argument('--model_save_path', default=root_dir + '/model_weights')
@@ -41,7 +57,8 @@ def add_default_args(parser, root_dir, rand_seed=None, possible_model_names=None
     # test_tube settings
     parser.add_argument('-en', '--tt_name', default='pt_test')
     parser.add_argument('-td', '--tt_description', default='pytorch lightning test')
-    parser.add_argument('--tt_save_path', default=root_dir + '/test_tube_logs', help='logging dir')
+    parser.add_argument('--tt_save_path', default=os.path.join(root_dir, 'test_tube_logs'),
+                        help='logging dir')
     parser.add_argument('--enable_single_run', dest='single_run', action='store_true')
     parser.add_argument('--nb_hopt_trials', default=1, type=int)
     parser.add_argument('--log_stdout', dest='log_stdout', action='store_true')
@@ -52,25 +69,30 @@ def add_default_args(parser, root_dir, rand_seed=None, possible_model_names=None
     parser.add_argument('--default_tensor_type', default='torch.cuda.FloatTensor', type=str)
     parser.add_argument('--use_amp', dest='use_amp', action='store_true')
     parser.add_argument('--check_grad_nans', dest='check_grad_nans', action='store_true')
-    parser.add_argument('--amp_level', default='O2',type=str)
-
+    parser.add_argument('--amp_level', default='O2', type=str)
 
     # run on hpc
     parser.add_argument('--on_cluster', dest='on_cluster', action='store_true')
 
     # FAST training
     # use these settings to make sure network has no bugs without running a full dataset
-    parser.add_argument('--fast_dev_run', dest='fast_dev_run', default=False, action='store_true', help='runs validation after 1 tng step')
-    parser.add_argument('--enable_tqdm', dest='enable_tqdm', default=False, action='store_true', help='false removes the prog bar')
-    parser.add_argument('--overfit', default=-1, type=float, help='% of dataset to use with this option. float, or -1 for none')
+    parser.add_argument('--fast_dev_run', dest='fast_dev_run', default=False, action='store_true',
+                        help='runs validation after 1 training step')
+    parser.add_argument('--enable_tqdm', dest='enable_tqdm', default=False, action='store_true',
+                        help='false removes the progress bar')
+    parser.add_argument('--overfit', default=-1, type=float,
+                        help='% of dataset to use with this option. float, or -1 for none')
 
     # debug args
     if rand_seed is not None:
         parser.add_argument('--random_seed', default=rand_seed, type=int)
 
-    parser.add_argument('--interactive', dest='interactive', action='store_true', help='runs on gpu without cluster')
-    parser.add_argument('--debug', dest='debug', action='store_true', help='enables/disables test tube')
-    parser.add_argument('--local', dest='local', action='store_true', help='enables local tng')
+    parser.add_argument('--interactive', dest='interactive', action='store_true',
+                        help='runs on gpu without cluster')
+    parser.add_argument('--debug', dest='debug', action='store_true',
+                        help='enables/disables test tube')
+    parser.add_argument('--local', dest='local', action='store_true',
+                        help='enables local training')
 
     # optimizer
-    parser.add_argument('--lr_scheduler_milestones', default=None, type=str)
+    parser.add_argument('--lr_scheduler_milestones', default=None, type=str)