release v0.5.1.3

Fixes lack of logging in logger (#319 )
* changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * changed rank 0 * models wait to restore weights * models wait to restore weights
2026-09-12 12:40:20 +08:00 · 2019-10-06 17:59:16 -04:00 · 2019-10-06 17:57:23 -04:00 · 2019-10-06 12:20:13 -04:00 · 2019-10-05 23:52:32 -04:00 · 2019-10-05 17:37:17 -04:00
79 changed files with 5887 additions and 3025 deletions
@@ -1,4 +1,7 @@
-#see https://github.com/codecov/support/wiki/Codecov-Yaml
+# 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
@@ -41,4 +44,3 @@ comment:
  behavior: default  # update if exists else create new
  # branches: *

-
@@ -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
@@ -1,5 +1,10 @@
 # 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!  
+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!   
+
+## 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.    
@@ -7,6 +7,10 @@ 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.

@@ -28,11 +32,5 @@ If applicable, add screenshots to help explain your problem.
 - Browser [e.g. chrome, safari]
 - Version [e.g. 22]

-**Smartphone (please complete the following information):**
- - Device: [e.g. iPhone6]
- - OS: [e.g. iOS8.1]
- - Browser [e.g. stock browser, safari]
- - Version [e.g. 22]
-
 **Additional context**
 Add any other context about the problem here.
@@ -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
@@ -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 🙃
@@ -11,6 +11,7 @@ pip-wheel-metadata/
 test_tube_exp/
 tests/tests_tt_dir/
 tests/save_dir
+default/

 # Byte-compiled / optimized / DLL files
 __pycache__/
@@ -0,0 +1,5 @@
+# use this to run tests
+rm -rf tests/save_dir*
+rm -rf tests/mlruns_*
+coverage run --source pytorch_lightning -m py.test pytorch_lightning tests examples -v --doctest-modules   
+coverage report -m
@@ -8,8 +8,6 @@
 # this file is *not* meant to cover or endorse the use of travis, but rather to
 # help confirm pull requests to this project.

-dist: xenial  # Ubuntu 16.04
-
 env:
  global:
    - DISPLAY=""
@@ -18,10 +16,36 @@ language: python

 matrix:
  include:
-    - python: 3.6
+    - os: linux
+      dist: xenial  # Ubuntu 16.04
+      python: 3.6
      env: TOXENV=py36
-    - python: 3.7
+    - 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
+      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
@@ -13,11 +13,16 @@ include LICENSE
 exclude *.sh
 exclude *.toml
 exclude *.svg    
-recursive-include examples *.py
 recursive-include pytorch_lightning *.py

+# include examples
+recursive-include examples *.py
+recursive-include examples *.md
+recursive-include examples *.sh
+
 # exclude tests from package
 recursive-exclude tests *
+recursive-exclude site *
 exclude tests

 # Exclude the documentation files
@@ -4,23 +4,25 @@

 # PyTorch Lightning

-**The PyTorch Keras for ML researchers. More control. Less boilerplate.**
+**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)
-<!-- 
-removed until windows install issues resolved.
-[![Build status](https://ci.appveyor.com/api/projects/status/rum89d7hq8l1kfye?svg=true)](https://ci.appveyor.com/project/Borda/pytorch-lightning) -->
+[![Build status](https://ci.appveyor.com/api/projects/status/rum89d7hq8l1kfye?svg=true)](https://ci.appveyor.com/project/Borda/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)
 -->
-[![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)
-[![license](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://github.com/williamFalcon/pytorch-lightning/blob/master/LICENSE)

 </div>

@@ -33,34 +35,42 @@ pip install pytorch-lightning
 **[View the docs here](https://williamfalcon.github.io/pytorch-lightning/)**

 ## What is it?  
-Lightning is a very lightweight wrapper on PyTorch. This means you don't have to learn a new library. It defers core training and validation logic to you and automates the rest. It guarantees tested, correct, modern best practices for the automated parts.
+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, multi-cluster training, 16-bit precision, early-stopping, model loading/saving, 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: The data and the training/validation loop logic. 
+Lightning sets up all the boilerplate state-of-the-art training for you so you can focus on the research.   

-Don't worry about training on multiple gpus or speeding up your code, lightning will do that for you!
-
---   
+---
+ 
 ## 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)    
- [Demos](https://github.com/williamFalcon/pytorch-lightning#demo)    
+- [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/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)
+- [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 os
 import torch
@@ -71,104 +81,117 @@ import torchvision.transforms as transforms

 import pytorch_lightning as pl

-class CoolModel(pl.LightningModule):
+class CoolSystem(pl.LightningModule):

    def __init__(self):
-        super(CoolModel, self).__init__()
+        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.view(x.size(0), -1)))

-    def my_loss(self, y_hat, y):
-        return F.cross_entropy(y_hat, y)
-
    def training_step(self, batch, batch_nb):
+        # REQUIRED
        x, y = batch
        y_hat = self.forward(x)
-        return {'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):
+        # OPTIONAL
        avg_loss = torch.stack([x['val_loss'] for x in outputs]).mean()
-        return {'avg_val_loss': avg_loss}
+        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)

    @pl.data_loader
-    def tng_dataloader(self):
+    def train_dataloader(self):
+        # REQUIRED
        return DataLoader(MNIST(os.getcwd(), train=True, download=True, transform=transforms.ToTensor()), batch_size=32)

    @pl.data_loader
    def val_dataloader(self):
+        # OPTIONAL
        return DataLoader(MNIST(os.getcwd(), train=True, download=True, transform=transforms.ToTensor()), batch_size=32)

    @pl.data_loader
    def test_dataloader(self):
+        # OPTIONAL
        return DataLoader(MNIST(os.getcwd(), train=True, 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

-model = CoolModel()
+model = CoolSystem()

 # most basic trainer, uses good defaults
 trainer = Trainer()    
 trainer.fit(model)   
 ```     

-Or with tensorboard logger and some options turned on such as multi-gpu, etc...    
+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   
-from test_tube import Experiment    
-
-# PyTorch summarywriter with a few bells and whistles    
-exp = Experiment(save_dir=os.getcwd())
-
 # train on cpu using only 10% of the data (for demo purposes)
-# pass in experi
-trainer = Trainer(experiment=exp, max_nb_epochs=1, train_percent_check=0.1)
+trainer = Trainer(max_nb_epochs=1, train_percent_check=0.1)

-# train on 4 gpus
-# trainer = Trainer(experiment=exp, max_nb_epochs=1, gpus=[0, 1, 2, 3])
+# train on 4 gpus (lightning chooses GPUs for you)
+# trainer = Trainer(max_nb_epochs=1, gpus=4)  
+
+# train on 4 gpus (you choose GPUs)
+# trainer = Trainer(max_nb_epochs=1, gpus=[0, 1, 3, 7])   

 # train on 32 gpus across 4 nodes (make sure to submit appropriate SLURM job)
-# trainer = Trainer(experiment=exp, max_nb_epochs=1, gpus=[0, 1, 2, 3, 4, 5, 6, 7], nb_gpu_nodes=4)
+# trainer = Trainer(max_nb_epochs=1, gpus=8, nb_gpu_nodes=4)

 # train (1 epoch only here for demo)
 trainer.fit(model)

-# view tensorflow logs 
+# view tensorboard logs 
 print('View tensorboard logs by running\ntensorboard --logdir %s' % os.getcwd())
 print('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?   

 Everything in gray!    
 You define the blue parts using the LightningModule interface:  

-![Ouverview](./docs/source/_static/overview_flat.jpg)
+![Overview](./docs/source/_static/overview_flat.jpg)

-```{.python}
+```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():
 ```
@@ -177,8 +200,8 @@ 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)
@@ -204,8 +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)
@@ -230,12 +253,13 @@ 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.   

 ![tensorboard-support](./docs/source/_static/tf_loss.png)

@@ -243,36 +267,21 @@ Lightning also adds a text column with all the hyperparameters for this experime

 ![tensorboard-support](./docs/source/_static/tf_tags.png)

-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     
-```    
-
 ## 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)
@@ -283,7 +292,7 @@ tensorboard --logdir /some/path
 - [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    

 - [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)
@@ -292,7 +301,7 @@ 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 metric row every k batches](https://williamfalcon.github.io/pytorch-lightning/Trainer/Logging/#log-metric-row-every-k-batches)
@@ -302,18 +311,20 @@ tensorboard --logdir /some/path
 - [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)
 - [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)

-###### 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/)
@@ -322,36 +333,38 @@ tensorboard --logdir /some/path
 - [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
-```bash
-# install lightning
-pip install pytorch-lightning
-
-# clone lightning for the demo
-git clone https://github.com/williamFalcon/pytorch-lightning.git
-cd pytorch-lightning
-cd 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'
-```
+## Examples   
+- [GAN](https://github.com/williamFalcon/pytorch-lightning/tree/master/examples/domain_templates/gan.py)    
+- [MNIST](https://github.com/williamFalcon/pytorch-lightning/tree/master/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/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.   
@@ -370,8 +383,37 @@ Nope.
 **Are there plans to support virtualenv?**    
 Nope. Please use anaconda or miniconda.    

-## Bleeding edge
-If you can't wait for the next release, install the most up to date code with:  
+**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**
+    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
-pip install git+https://github.com/williamFalcon/pytorch-lightning.git@master --upgrade
+pip install https://github.com/williamFalcon/pytorch-lightning/archive/0.4.4.zip --upgrade
 ```
@@ -45,9 +45,7 @@ install:
  # directly to master instead of just PR builds (or the converse).
  - SET PATH=%PYTHON%;%PYTHON%\\Scripts;%path%
  - pip install -U --user pip
-  - pip install "https://download.pytorch.org/whl/cu90/torch-1.1.0-cp%PIP_PYVER%-cp%PIP_PYVER%m-win_amd%PYTHON_ARCH%.whl"
-    pip install "https://download.pytorch.org/whl/cu90/torchvision-0.3.0-cp%PIP_PYVER%-cp%PIP_PYVER%m-win_amd%PYTHON_ARCH%.whl"
-  - pip install -r requirements.txt
+  - 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")
@@ -9,22 +9,21 @@ 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)
-
- [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**:   

- [on_save_checkpoint](RequiredTrainerInterface.md#on_save_checkpoint)
- [on_load_checkpoint](RequiredTrainerInterface.md#on_load_checkpoint)
- [update_tng_log_metrics](RequiredTrainerInterface.md#update_tng_log_metrics)
- [add_model_specific_args](RequiredTrainerInterface.md#add_model_specific_args)
+- [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   
@@ -48,37 +47,53 @@ class CoolModel(pl.LightningModule):
    def forward(self, x):
        return torch.relu(self.l1(x.view(x.size(0), -1)))

-    def my_loss(self, y_hat, y):
-        return F.cross_entropy(y_hat, y)
-
    def training_step(self, batch, batch_nb):
+        # REQUIRED
        x, y = batch
        y_hat = self.forward(x)
-        return {'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):
+        # 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)

    @pl.data_loader
-    def tng_dataloader(self):
+    def train_dataloader(self):
        return DataLoader(MNIST(os.getcwd(), train=True, download=True, transform=transforms.ToTensor()), batch_size=32)

    @pl.data_loader
    def val_dataloader(self):
+        # OPTIONAL
+        # can also return a list of val dataloaders
        return DataLoader(MNIST(os.getcwd(), train=True, download=True, transform=transforms.ToTensor()), batch_size=32)

    @pl.data_loader
    def test_dataloader(self):
-        return DataLoader(MNIST(os.getcwd(), train=True, download=True, transform=transforms.ToTensor()), 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?     
@@ -90,12 +105,12 @@ The LightningModule interface is on the right. Each method corresponds to a part
  </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.
@@ -104,7 +119,7 @@ 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**   
@@ -114,14 +129,15 @@ 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)
@@ -129,46 +145,147 @@ def training_step(self, data_batch, batch_nb):
    
    output = {
        'loss': loss, # required
-        'prog': {'tng_loss': loss, 'batch_nb': batch_nb} # optional
+        'progress_bar': {'training_loss': loss}, # optional (MUST ALL BE TENSORS)
+        'log': {'training_loss': loss} # optional (MUST ALL BE TENSORS)
    }
    
    # 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    
+```    
+
+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)
@@ -183,31 +300,49 @@ 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)
-```
+```   
+If you didn't define a validation_step, this won't be called.       

-Called at the end of the validation loop with the output of each validation_step.
+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.    

 **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):
    """
@@ -223,38 +358,197 @@ 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
+
+    val_loss_mean /= i
+    val_acc_mean /= i
+    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
 ```

-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.
+### test_step

+``` {.python}
+# if you have one test dataloader:
+def test_step(self, batch, batch_nb)   

-##### Return
-List or Tuple - List of optimizers with an optional second list of learning-rate schedulers
+# 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}
-# most cases
-def configure_optimizers(self):
-    opt = Adam(self.parameters(), lr=0.01)
-    return [opt]
+# CASE 1: A single test dataset
+def test_step(self, batch, batch_nb):
+    x, y = batch
    
-# gan example, with scheduler for discriminator
-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]
+    # 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
 ```

 --- 
@@ -299,44 +593,21 @@ def on_load_checkpoint(self, checkpoint):
    self.something_cool_i_want_to_save = checkpoint['something_cool_i_want_to_save']
 ```

--- 
-### tng_dataloader 
-
-``` {.python}
-@pl.data_loader
-def tng_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.
-
-##### Return
-PyTorch DataLoader
-
-**Example**
-
-``` {.python}
-@pl.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
-```
-
 --- 
 ### val_dataloader 

 ``` {.python}
@pl.data_loader
-def tng_dataloader(self)
+def val_dataloader(self)
 ```
-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.
+**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**

@@ -352,8 +623,16 @@ 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 

@@ -361,7 +640,11 @@ def val_dataloader(self):
@pl.data_loader
 def test_dataloader(self)
 ```
+**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
@@ -382,26 +665,6 @@ 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 

@@ -424,7 +687,7 @@ 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)
@@ -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    

 ---
@@ -2,17 +2,25 @@ 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)
@@ -38,6 +46,7 @@ trainer.fit(model)
 ```

 The trainer restores:  
+
 - global_step    
 - current_epoch    
 - All optimizers    
@@ -65,4 +74,4 @@ for scheduler, lrs_state in zip(self.lr_schedulers, lr_schedulers):

 # uses the model you passed into trainer        
 model.load_state_dict(checkpoint['state_dict'])
-```    
+```    
@@ -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.
@@ -32,12 +49,24 @@ Below are the possible configurations we support.

 | 1 GPU  | 1+ GPUs  | DP  | DDP  | 16-bit  | command |
 |---|---|---|---|---|---|
-| Y  |   |   |   |  | ```Trainer(gpus=[0])``` |
-| Y  |   |   |   | Y | ```Trainer(gpus=[0], use_amp=True)``` |
-|   | Y | Y |   |   | ```Trainer(gpus=[0, ...])``` |
-|   | Y |  | Y  |  | ```Trainer(gpus=[0, ...], distributed_backend='ddp')``` |
-|   | Y |  | Y  | Y | ```Trainer(gpus=[0, ...], distributed_backend='ddp', use_amp=True)``` |
+| 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)
+Trainer(gpus=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')
+```

 ---
 #### CUDA flags   
@@ -49,6 +78,9 @@ Lightning sets these for you automatically, there's NO NEED to do this yourself.
 # 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.    
@@ -56,6 +88,21 @@ 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" ./
 ```

@@ -70,7 +117,7 @@ trainer = Trainer(amp_level='O2', use_amp=False)
 Make sure you're on a GPU machine. 
 ```python
 # DEFAULT
-trainer = Trainer(gpus=[0])
+trainer = Trainer(gpus=1)
 ```

 ---
@@ -78,50 +125,63 @@ 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
-# 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('export MASTER_PORT=%r' % 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).   

@@ -136,6 +196,58 @@ 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/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.   
@@ -1,11 +1,117 @@
-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/).
+
+```{.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)
+```
+
+---
+#### 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)
+```
+
+---
+#### 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
+self.logger
+
+# add an image if using TestTubeLogger
+self.logger.experiment.add_image(...)
+```
+
+
 #### Display metrics in progress bar 
 ``` {.python}
 # DEFAULT
-trainer = Trainer(progress_bar=True)
+trainer = Trainer(show_progress_bar=True)
 ```

 ---
@@ -13,7 +119,21 @@ 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')
 ```

 ---
@@ -30,61 +150,21 @@ 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

---
-#### 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)
-```
+args = parser.parse_args()
+model = MyModel(args)

---
-### Tensorboard support   
-In the LightningModule you can access the experiment logger by doing:
-```python
-self.experiment
-
-# add image
-# Look at PyTorch SummaryWriter docs for what you can do.   
-self.experiment.add_image(...)
-```
-
-The experiment object is a strict subclass of PyTorch SummaryWriter. However, this class
-also snapshots every detail about the experiment (data folder paths, code, hyperparams),
-and allows you to visualize it using tensorboard.
-``` {.python}
-from test_tube import Experiment, HyperOptArgumentParser
-
-# exp hyperparams
-args = HyperOptArgumentParser()
-hparams = args.parse_args()
-
-# this is a summaryWriter with nicer logging structure
-exp = Experiment(save_dir='/some/path', create_git_tag=True)
-
-# track experiment details (must be ArgumentParser or HyperOptArgumentParser).
-# each option in the parser is tracked
-exp.argparse(hparams)
-exp.tag({'description': 'running demo'})
-
-# trainer uses the exp object to log exp data
-trainer = Trainer(experiment=exp)
+logger = TestTubeLogger(...)
+t = Trainer(logger=logger)
 trainer.fit(model)
-
-# view logs at:
-# tensorboard --logdir /some/path   
 ```

 ---
@@ -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

@@ -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...)  
+ 
@@ -19,6 +19,25 @@ It can be useful to force training for a minimum number of epochs or limit to a
 trainer = Trainer(min_nb_epochs=1, max_nb_epochs=1000)
 ```

+---
+#### Early stopping
+The trainer already sets up default early stopping for you. 
+To modify this behavior, pass in your own EarlyStopping callback.
+``` {.python}
+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'
+)
+
+trainer = Trainer(early_stop_callback=early_stop_callback)
+```
+
 ---
 #### 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)
@@ -28,15 +47,18 @@ trainer = Trainer(enable_early_stop=True)
 ```

 ---
-#### Gradient Clipping 
-Use this to turn off early stopping and run training to the [max_epoch](#force-training-for-min-or-max-epochs)
+#### 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=0)
+trainer = Trainer(gradient_clip_val=0)
+
+# clip gradients with norm above 0.5
+trainer = Trainer(gradient_clip_val=0.5)
 ```

-
-
 ---
 #### Inspect gradient norms
 Looking at grad norms can help you figure out where training might be going wrong.
@@ -51,7 +73,10 @@ 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)
@@ -5,8 +5,6 @@ Below are all the things lightning automates for you in the validation loop.
 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)
@@ -54,4 +58,6 @@ 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.
@@ -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)
@@ -58,15 +58,52 @@ def on_post_performance_check(self):
 ```

 ---
-#### on_tng_metrics
-Called in the training loop, right before metrics are logged.
-Although you can log at any time by using self.experiment, you can use
-this callback to modify what will be logged.
+#### 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
-def on_tng_metrics(self, metrics):
-    # do something before validation end
+# 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.
@@ -90,5 +127,5 @@ def on_after_backward(self):
        for k, v in params.items():
            grads = v
            name = k
-            self.experiment.add_histogram(tag=name, values=grads, global_step=self.trainer.global_step)
+            self.logger.experiment.add_histogram(tag=name, values=grads, global_step=self.trainer.global_step)
 ```
@@ -19,6 +19,7 @@ But of course the fun is in all the advanced things it can do:

 **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)
@@ -35,7 +36,7 @@ But of course the fun is in all the advanced things it can do:
 - [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)


@@ -60,14 +61,16 @@ But of course the fun is in all the advanced things it can do:

 **Training loop**    

- [Accumulate gradients](https://williamfalcon.github.io/pytorch-lightning/Trainer/Training%20Loop/#accumulated-gradients)
+- [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)

 **Validation loop**    

@@ -77,3 +80,8 @@ But of course the fun is in all the advanced things it can do:
 - [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/)  
@@ -3,7 +3,7 @@ In 99% of cases you want to just copy [this template](https://github.com/william

 ```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/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.
@@ -1,17 +1,67 @@
 ###### New project Quick Start    
-To start a new project you define two files, a LightningModule and a Trainer file.    
+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.    

-A separate trainer file allows to run many LightningModules. Each LightningModule has the core
-logic to a particular research project.    
+###### 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
+```   

-For example, one lightningModule could be an image classifier, the other
-one could be a seq-2-seq model, both (optionally) ran by the same trainer file.
+###### 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 Trainer Template](https://github.com/williamFalcon/pytorch-lightning/blob/master/examples/new_project_templates/single_cpu_template.py) 
-    - [Multi-GPU Trainer Template](https://github.com/williamFalcon/pytorch-lightning/blob/master/examples/new_project_templates/single_gpu_node_template.py)
-    - [GPU cluster Trainer Template](https://github.com/williamFalcon/pytorch-lightning/blob/master/examples/new_project_templates/multi_node_cluster_template.py)
+    - [Basic CPU, GPU Trainer Template](https://github.com/williamFalcon/pytorch-lightning/tree/master/examples/basic_examples) 
+    - [GPU cluster Trainer Template](https://github.com/williamFalcon/pytorch-lightning/tree/master/examples/multi_node_examples)

 ###### Docs shortcuts
 - [LightningModule](LightningModule/RequiredTrainerInterface/)  
@@ -26,6 +76,7 @@ one could be a seq-2-seq model, both (optionally) ran by the same trainer file.

 ###### 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)
@@ -69,12 +120,14 @@ one could be a seq-2-seq model, both (optionally) ran by the same trainer file.

 - [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)

 ###### Validation loop    

@@ -85,3 +138,5 @@ one could be a seq-2-seq model, both (optionally) ran by the same trainer file.
 - [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/)  
@@ -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.
@@ -1,4 +1,4 @@
-from .new_project_templates.lightning_module_template import LightningTemplateModel
+from .basic_examples.lightning_module_template import LightningTemplateModel

 __all__ = [
    'LightningTemplateModel'
@@ -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
+```
@@ -0,0 +1,53 @@
+"""
+Runs a model on a single node across N-gpus.
+"""
+import os
+import numpy as np
+import torch
+
+from argparse import ArgumentParser
+from pytorch_lightning import Trainer
+from examples.basic_examples.lightning_module_template import LightningTemplateModel
+
+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)
@@ -0,0 +1,78 @@
+"""
+Runs a model on a single node across N-gpus.
+"""
+import os
+import numpy as np
+import torch
+
+from argparse import ArgumentParser
+from pytorch_lightning import Trainer
+from examples.basic_examples.lightning_module_template import LightningTemplateModel
+
+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)
@@ -8,7 +8,7 @@ from torchvision.datasets import MNIST
 import torchvision.transforms as transforms
 import torch
 import torch.nn.functional as F
-from test_tube import HyperOptArgumentParser
+from argparse import ArgumentParser
 from torch import optim
 from torch.utils.data import DataLoader
 from torch.utils.data.distributed import DistributedSampler
@@ -79,14 +79,14 @@ 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)
@@ -95,7 +95,7 @@ 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)

        output = OrderedDict({
@@ -105,13 +105,13 @@ class LightningTemplateModel(LightningModule):
        # 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)

@@ -126,7 +126,7 @@ 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)

@@ -160,15 +160,16 @@ class LightningTemplateModel(LightningModule):

            # reduce manually when using dp
            val_acc = output['val_acc']
-            if self.trainer.use_dp:
-                val_acc_mean = torch.mean(val_acc)
+            if self.trainer.use_dp or self.trainer.use_ddp2:
+                val_acc = torch.mean(val_acc)

-            val_acc_mean += val_acc_mean
+            val_acc_mean += val_acc

        val_loss_mean /= len(outputs)
        val_acc_mean /= len(outputs)
-        tqdm_dic = {'val_loss': val_loss_mean, 'val_acc': val_acc_mean}
-        return tqdm_dic
+        tqdm_dict = {'val_loss': val_loss_mean, 'val_acc': val_acc_mean}
+        result = {'progress_bar': tqdm_dict, 'logs': tqdm_dict}
+        return result

    # ---------------------
    # TRAINING SETUP
@@ -189,30 +190,27 @@ class LightningTemplateModel(LightningModule):
        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:
-            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

    @pl.data_loader
-    def tng_dataloader(self):
-        print('tng data loader called')
+    def train_dataloader(self):
+        print('training data loader called')
        return self.__dataloader(train=True)

    @pl.data_loader
@@ -233,31 +231,23 @@ class LightningTemplateModel(LightningModule):
        :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.add_argument('--in_features', default=28 * 28, type=int)
        parser.add_argument('--out_features', default=10, type=int)
        # use 500 for CPU, 50000 for GPU to see speed difference
        parser.add_argument('--hidden_dim', default=50000, type=int)
-        parser.opt_list('--drop_prob', default=0.2, options=[0.2, 0.5], type=float, tunable=False)
+        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 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
@@ -0,0 +1,178 @@
+"""
+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
+"""
+from argparse import ArgumentParser
+import os
+import numpy as np
+
+import torchvision
+import torchvision.transforms as transforms
+from torchvision.datasets import MNIST
+
+from torch.utils.data import DataLoader
+
+import torch.nn as nn
+import torch.nn.functional as F
+import torch
+
+import pytorch_lightning as pl
+from test_tube import Experiment
+
+
+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
+
+    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
+
+        # 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)
+
+            return g_loss
+
+        # 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
+
+            return d_loss
+
+    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 main(hparams):
+    # save tensorboard logs
+    exp = Experiment(save_dir=os.getcwd())
+
+    # init model
+    model = GAN(hparams)
+
+    # fit trainer on CPU
+    trainer = pl.Trainer(experiment=exp, max_nb_epochs=200)
+    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)
@@ -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
+```
@@ -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
@@ -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
@@ -0,0 +1,55 @@
+"""
+Multi-node example (GPU)
+"""
+import os
+import numpy as np
+import torch
+
+from argparse import ArgumentParser
+from pytorch_lightning import Trainer
+from examples.basic_examples.lightning_module_template import LightningTemplateModel
+
+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)
@@ -0,0 +1,55 @@
+"""
+Multi-node example (GPU)
+"""
+import os
+import numpy as np
+import torch
+
+from argparse import ArgumentParser
+from pytorch_lightning import Trainer
+from examples.basic_examples.lightning_module_template import LightningTemplateModel
+
+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)
@@ -1,172 +0,0 @@
-"""
-Multi-node example (GPU)
-"""
-import os
-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.callbacks import EarlyStopping, ModelCheckpoint
-
-from examples.new_project_templates.lightning_module_template import LightningTemplateModel
-
-SEED = 2334
-torch.manual_seed(SEED)
-np.random.seed(SEED)
-
-
-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)
@@ -1,109 +0,0 @@
-"""
-Runs a model on a single node on CPU only..
-"""
-import os
-import numpy as np
-import torch
-
-from test_tube import HyperOptArgumentParser, Experiment
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint
-
-from examples.new_project_templates.lightning_module_template import LightningTemplateModel
-
-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
-    # ------------------------
-    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('RUNNING ON CPU')
-    main(hyperparams)
@@ -1,114 +0,0 @@
-"""
-16-bit single node, CPU example
-"""
-import os
-import numpy as np
-import torch
-
-from test_tube import HyperOptArgumentParser, Experiment
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint
-
-from examples.new_project_templates.lightning_module_template import LightningTemplateModel
-
-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
-    # ------------------------
-    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.'
-                                    'value -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('RUNNING INTERACTIVE MODE ON GPUS. gpu ids: %i' % hyperparams.gpus)
-    main(hyperparams)
@@ -1,114 +0,0 @@
-"""
-Runs a model on a single node across N-gpus.
-"""
-import os
-import numpy as np
-import torch
-
-from test_tube import HyperOptArgumentParser, Experiment
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint
-
-from examples.new_project_templates.lightning_module_template import LightningTemplateModel
-
-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
-    # ------------------------
-    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,
-        distributed_backend='ddp'
-    )
-
-    # ------------------------
-    # 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.'
-                                    ' value -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('RUNNING INTERACTIVE MODE ON GPUS. gpu ids: %i' % hyperparams.gpus)
-    main(hyperparams)
@@ -1,113 +0,0 @@
-"""
-Runs a model on a single node across N-gpus using dataParallel
-"""
-import os
-import numpy as np
-import torch
-
-from test_tube import HyperOptArgumentParser, Experiment
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.callbacks import EarlyStopping, ModelCheckpoint
-
-from examples.new_project_templates.lightning_module_template import LightningTemplateModel
-
-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
-    # ------------------------
-    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.'
-                                    ' value -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('RUNNING INTERACTIVE MODE ON GPUS. gpu ids: %i' % hyperparams.gpus)
-    main(hyperparams)
@@ -1,74 +0,0 @@
-import os
-import sys
-
-from test_tube import HyperOptArgumentParser, Experiment
-from pytorch_lightning.models.trainer import Trainer
-from pytorch_lightning.utilities.arg_parse import add_default_args
-from pytorch_lightning.callbacks.pt_callbacks import EarlyStopping, ModelCheckpoint
-
-from examples.new_project_templates.lightning_module_template import LightningTemplateModel
-
-
-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 = LightningTemplateModel(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 = LightningTemplateModel.add_model_specific_args(parent_parser)
-    hyperparams = parser.parse_args()
-
-    # train model
-    main(hyperparams)
@@ -2,9 +2,15 @@ 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.'

 dev_addr: '0.0.0.0:8000'
 #google_analytics: ['UA-aasd', 'sitename']
+
+markdown_extensions:
+  - codehilite:
+      guess_lang: false
+      linenums: true
@@ -1,4 +1,4 @@
-from .models.trainer import Trainer
+from .trainer.trainer import Trainer
 from .root_module.root_module import LightningModule
 from .root_module.decorators import data_loader

@@ -1,6 +1,7 @@
-from .pt_callbacks import EarlyStopping, ModelCheckpoint
+from .pt_callbacks import EarlyStopping, ModelCheckpoint, GradientAccumulationScheduler

 __all__ = [
    'EarlyStopping',
    'ModelCheckpoint',
+    'GradientAccumulationScheduler',
 ]
@@ -1,5 +1,6 @@
 import os
 import shutil
+import warnings

 import numpy as np

@@ -11,7 +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
@@ -254,6 +254,37 @@ class ModelCheckpoint(Callback):
                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]
@@ -0,0 +1,10 @@
+from .base import LightningLoggerBase, rank_zero_only
+
+try:
+    from .test_tube_logger import TestTubeLogger
+except ModuleNotFoundError:
+    pass
+try:
+    from .mlflow_logger import MLFlowLogger
+except ModuleNotFoundError:
+    pass
@@ -0,0 +1,71 @@
+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 version(self):
+        """Return the experiment version"""
+        return None
@@ -0,0 +1,56 @@
+from time import time
+from logging import getLogger
+
+import mlflow
+
+from .base import LightningLoggerBase, rank_zero_only
+
+logger = getLogger(__name__)
+
+
+class MLFlowLogger(LightningLoggerBase):
+    def __init__(self, experiment_name, tracking_uri=None):
+        super().__init__()
+        self.client = mlflow.tracking.MlflowClient(tracking_uri)
+        self.experiment_name = experiment_name
+        self._run_id = None
+
+    @property
+    def run_id(self):
+        if self._run_id is not None:
+            return self._run_id
+
+        experiment = self.client.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.client.create_experiment(self.experiment_name)
+            experiment = self.client.get_experiment_by_name(self.experiment_name)
+
+        run = self.client.create_run(experiment.experiment_id)
+        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.client.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.client.log_metric(self.run_id, k, v, timestamp_ms, step_num)
+
+    def save(self):
+        pass
+
+    @rank_zero_only
+    def finalize(self, status="FINISHED"):
+        self.client.set_terminated(self.run_id, status)
@@ -0,0 +1,93 @@
+import os.path
+from copy import copy
+
+from .base import LightningLoggerBase, rank_zero_only
+
+from test_tube import Experiment
+
+
+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):
+        self.experiment.argparse(params)
+
+    @rank_zero_only
+    def log_metrics(self, metrics, step_num=None):
+        self.experiment.log(metrics, global_step=step_num)
+
+    @rank_zero_only
+    def save(self):
+        self.experiment.save()
+
+    @rank_zero_only
+    def finalize(self, status):
+        self.save()
+        self.close()
+
+    def close(self):
+        self.experiment.close()
+
+    @property
+    def rank(self):
+        if self._experiment is None:
+            return self._rank
+        else:
+            return self.experiment.rank
+
+    @rank.setter
+    def rank(self, value):
+        if self._experiment is None:
+            self._rank = value
+        else:
+            return self.experiment.rank
+
+    @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)
@@ -56,6 +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])

@@ -85,16 +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():
@@ -153,6 +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)
                # ---------------
@@ -163,6 +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))
@@ -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
@@ -5,12 +5,12 @@ class ModelHooks(torch.nn.Module):

    def on_sanity_check_start(self):
        """
-        Called before starting validate
+        Called before starting evaluate
        :return:
        """
        pass

-    def on_batch_start(self, data_batch):
+    def on_batch_start(self, batch):
        pass

    def on_batch_end(self):
@@ -28,9 +28,6 @@ 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()
@@ -178,6 +178,33 @@ def count_mem_items():  # pragma: no cover
    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_mem = 1000000
+        min_k = None
+        max_mem = 0
+        max_k = None
+        for k, v in memory_map:
+            if v > max_mem:
+                max_mem = v
+                max_k = k
+            if v < min_mem:
+                min_mem = v
+                min_k = k
+
+        memory_map = {min_k: min_mem, max_k: max_mem}
+
+    return memory_map
+
+
 def get_gpu_memory_map():
    """Get the current gpu usage.

@@ -196,6 +223,6 @@ def get_gpu_memory_map():
    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 = 'gpu_%i' % k
+        k = f'gpu_{k}'
        gpu_memory_map[k] = v
    return gpu_memory_map
@@ -1,12 +1,3 @@
-import os
-import re
-
-import torch
-
-from pytorch_lightning.pt_overrides.override_data_parallel import (
-    LightningDistributedDataParallel, LightningDataParallel)
-
-
 class ModelIO(object):

    def on_load_checkpoint(self, checkpoint):
@@ -41,221 +32,3 @@ class ModelIO(object):
        :return:
        """
        pass
-
-
-class TrainerIO(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
-
-    # --------------------
-    # MODEL SAVE CHECKPOINT
-    # --------------------
-    def save_checkpoint(self, filepath):
-        checkpoint = self.dump_checkpoint()
-
-        # do the actual save
-        torch.save(checkpoint, filepath)
-
-    def restore(self, checkpoint_path, on_gpu):
-
-        if on_gpu:
-            checkpoint = torch.load(checkpoint_path)
-        else:
-            checkpoint = torch.load(checkpoint_path, 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'])
-
-    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
-
-        # 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 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
-        # only if proc 0 so we don't trigger world_size resubmits
-        if self.proc_rank == 0:
-            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)
-
-        # 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, 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, 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
@@ -2,7 +2,8 @@ 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.trainer.trainer_io import load_hparams_from_tags_csv
+from pytorch_lightning.root_module.model_saving import ModelIO
 from pytorch_lightning.root_module.hooks import ModelHooks
 from pytorch_lightning.root_module.decorators import data_loader

@@ -18,11 +19,15 @@ 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):
        """
@@ -33,29 +38,52 @@ 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 loss, dict with metrics for tqdm
+        :param called with batch, batch_nb
+        additional: optimizer_i if multiple optimizers used
        :return:
        """
        raise NotImplementedError

+    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_optimizers(self):
        """
@@ -64,10 +92,28 @@ class LightningModule(GradInformation, ModelIO, ModelHooks):
        """
        raise NotImplementedError

-    @data_loader
-    def tng_dataloader(self):
+    def optimizer_step(self, epoch_nb, batch_nb, optimizer, optimizer_i, second_order_closure=None):
        """
-        Implement a function to load an h5py of this data
+        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()
+
+    @data_loader
+    def train_dataloader(self):
+        """
+        Implement a PyTorch DataLoader
        :return:
        """
        raise NotImplementedError
@@ -75,39 +121,34 @@ class LightningModule(GradInformation, ModelIO, ModelHooks):
    @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)
@@ -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,
+)
@@ -14,256 +14,14 @@ from test_tube import HyperOptArgumentParser
 from pytorch_lightning.root_module.root_module import LightningModule
 from pytorch_lightning import data_loader

+from .lm_test_module_base import LightningTestModelBase
+from .lm_test_module_mixins import LightningValidationMixin, LightningTestMixin

-class LightningTestModel(LightningModule):
+
+class LightningTestModel(LightningValidationMixin, LightningTestMixin, LightningTestModelBase):
    """
-    Sample model to show how to define a template
+    Most common test case. Validation and test dataloaders
    """

-    def __init__(self, hparams, force_remove_distributed_sampler=False):
-        """
-        Pass in parsed HyperOptArgumentParser to the model
-        :param hparams:
-        """
-        # init superclass
-        super(LightningTestModel, self).__init__()
-        self.hparams = hparams
-
-        self.batch_size = hparams.batch_size
-
-        # if you specify an example input, the summary will show input/output for each layer
-        self.example_input_array = torch.rand(5, 28 * 28)
-
-        # remove to test warning for dist sampler
-        self.force_remove_distributed_sampler = force_remove_distributed_sampler
-
-        # build model
-        self.__build_model()
-
-    # ---------------------
-    # MODEL SETUP
-    # ---------------------
-    def __build_model(self):
-        """
-        Layout model
-        :return:
-        """
-        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)
-
-    # ---------------------
-    # TRAINING
-    # ---------------------
-    def forward(self, x):
-        """
-        No special modification required for lightning, define as you normally would
-        :param x:
-        :return:
-        """
-
-        x = self.c_d1(x)
-        x = torch.tanh(x)
-        x = self.c_d1_bn(x)
-        x = self.c_d1_drop(x)
-
-        x = self.c_d2(x)
-        logits = F.log_softmax(x, dim=1)
-
-        return logits
-
-    def loss(self, labels, logits):
-        nll = F.nll_loss(logits, labels)
-        return nll
-
-    def training_step(self, data_batch, batch_i):
-        """
-        Lightning calls this inside the training loop
-        :param data_batch:
-        :return:
-        """
-        # forward pass
-        x, y = data_batch
-        x = x.view(x.size(0), -1)
-
-        y_hat = self.forward(x)
-
-        # calculate loss
-        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:
-            loss_val = loss_val.unsqueeze(0)
-
-        # alternate possible outputs to test
-        if self.trainer.batch_nb % 1 == 0:
-            output = OrderedDict({
-                'loss': loss_val,
-                'prog': {'some_val': loss_val * loss_val}
-            })
-            return output
-        if self.trainer.batch_nb % 2 == 0:
-            return loss_val
-
-    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 batch_i % 1 == 0:
-            output = OrderedDict({
-                'val_loss': loss_val,
-                'val_acc': val_acc,
-            })
-            return output
-        if batch_i % 2 == 0:
-            return val_acc
-
-        if batch_i % 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):
+    def on_training_metrics(self, logs):
        logs['some_tensor_to_test'] = torch.rand(1)
-
-    # ---------------------
-    # TRAINING SETUP
-    # ---------------------
-    def configure_optimizers(self):
-        """
-        return whatever optimizers we want here
-        :return: list of optimizers
-        """
-        # try no scheduler for this model (testing purposes)
-        optimizer = optim.Adam(self.parameters(), lr=self.hparams.learning_rate)
-
-        # 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)
-
-        # 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:
-                train_sampler = DistributedSampler(dataset, rank=self.trainer.proc_rank)
-                batch_size = batch_size // self.trainer.world_size  # scale batch size
-        except Exception:
-            pass
-
-        should_shuffle = train_sampler is None
-        loader = DataLoader(
-            dataset=dataset,
-            batch_size=batch_size,
-            shuffle=should_shuffle,
-            sampler=train_sampler
-        )
-
-        return loader
-
-    @data_loader
-    def tng_dataloader(self):
-        return self.__dataloader(train=True)
-
-    @data_loader
-    def val_dataloader(self):
-        return self.__dataloader(train=False)
-
-    @data_loader
-    def test_dataloader(self):
-        return self.__dataloader(train=False)
-
-    @staticmethod
-    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])
-
-        # param overwrites
-        # parser.set_defaults(gradient_clip=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('--out_features', default=10, type=int)
-        # 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],
-                        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 gpus being used across all nodes')
-        return parser
@@ -0,0 +1,199 @@
+import os
+from collections import OrderedDict
+
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from torch import optim
+from torch.utils.data import DataLoader
+from torch.utils.data.distributed import DistributedSampler
+from torchvision.datasets import MNIST
+from torchvision import transforms
+from test_tube import HyperOptArgumentParser
+
+from pytorch_lightning.root_module.root_module import LightningModule
+from pytorch_lightning import data_loader
+
+
+class LightningTestModelBase(LightningModule):
+    """
+    Base LightningModule for testing. Implements only the required
+    interface
+    """
+
+    def __init__(self, hparams, force_remove_distributed_sampler=False):
+        """
+        Pass in parsed HyperOptArgumentParser to the model
+        :param hparams:
+        """
+        # init superclass
+        super(LightningTestModelBase, self).__init__()
+        self.hparams = hparams
+
+        self.batch_size = hparams.batch_size
+
+        # if you specify an example input, the summary will show input/output for each layer
+        self.example_input_array = torch.rand(5, 28 * 28)
+
+        # remove to test warning for dist sampler
+        self.force_remove_distributed_sampler = force_remove_distributed_sampler
+
+        # build model
+        self.__build_model()
+
+    # ---------------------
+    # MODEL SETUP
+    # ---------------------
+    def __build_model(self):
+        """
+        Layout model
+        :return:
+        """
+        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)
+
+    # ---------------------
+    # TRAINING
+    # ---------------------
+    def forward(self, x):
+        """
+        No special modification required for lightning, define as you normally would
+        :param x:
+        :return:
+        """
+
+        x = self.c_d1(x)
+        x = torch.tanh(x)
+        x = self.c_d1_bn(x)
+        x = self.c_d1_drop(x)
+
+        x = self.c_d2(x)
+        logits = F.log_softmax(x, dim=1)
+
+        return logits
+
+    def loss(self, labels, logits):
+        nll = F.nll_loss(logits, labels)
+        return nll
+
+    def training_step(self, batch, batch_idx):
+        """
+        Lightning calls this inside the training loop
+        :param batch:
+        :return:
+        """
+        # forward pass
+        x, y = batch
+        x = x.view(x.size(0), -1)
+
+        y_hat = self.forward(x)
+
+        # calculate loss
+        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:
+            loss_val = loss_val.unsqueeze(0)
+
+        # alternate possible outputs to test
+        if self.trainer.batch_nb % 1 == 0:
+            output = OrderedDict({
+                '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 loss_val
+
+    # ---------------------
+    # TRAINING SETUP
+    # ---------------------
+    def configure_optimizers(self):
+        """
+        return whatever optimizers we want here.
+        :return: list of optimizers
+        """
+        # 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)
+
+        # 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)
+
+        # when using multi-node we need to add the datasampler
+        train_sampler = None
+        batch_size = self.hparams.batch_size
+
+        try:
+            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:
+            pass
+
+        should_shuffle = train_sampler is None
+        loader = DataLoader(
+            dataset=dataset,
+            batch_size=batch_size,
+            shuffle=should_shuffle,
+            sampler=train_sampler
+        )
+
+        return loader
+
+    @data_loader
+    def train_dataloader(self):
+        return self._dataloader(train=True)
+
+    @staticmethod
+    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])
+
+        # param overwrites
+        # 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('--out_features', default=10, type=int)
+        # 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],
+                        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 gpus being used across all nodes')
+        return parser
@@ -0,0 +1,391 @@
+import os
+from collections import OrderedDict
+
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from torch import optim
+from torch.utils.data import DataLoader
+from torch.utils.data.distributed import DistributedSampler
+from torchvision.datasets import MNIST
+from torchvision import transforms
+from test_tube import HyperOptArgumentParser
+
+from pytorch_lightning.root_module.root_module import LightningModule
+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:
+                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
+
+        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
@@ -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()
@@ -0,0 +1,330 @@
+import os
+import re
+import signal
+import pdb
+from subprocess import call
+
+import torch
+import torch.distributed as dist
+from pytorch_lightning.pt_overrides.override_data_parallel import (
+    LightningDistributedDataParallel, LightningDataParallel)
+
+
+class TrainerIO(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, if we use the same experiment version, then restore the latest ckpt.
+        AFTER that, if we find weights from hpc checkpoint, then restore that.
+        :param model:
+        :return:
+        """
+        # restore weights if same exp version
+        self.restore_state_if_checkpoint_exists(model)
+
+        # if script called from hpc resubmit, load weights
+        self.restore_hpc_weights_if_needed(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()
+
+    def restore_state_if_checkpoint_exists(self, model):
+        # do nothing if there's not dir or callback
+        no_ckpt_callback = self.checkpoint_callback is None
+        if no_ckpt_callback or not os.path.exists(self.checkpoint_callback.filepath):
+            return
+
+        # 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)
+            print(f'model and trainer restored from checkpoint: {last_ckpt_path}')
+
+    # --------------------
+    # 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:
+            print('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
+            print('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
+            print('\nrequeing job {}...'.format(job_id))
+            result = call(cmd, shell=True)
+
+            # print result text
+            if result == 0:
+                print('requeued exp ', job_id)
+            else:
+                print('requeue failed...')
+
+            # close experiment to avoid issues
+            self.logger.close()
+
+    def term_handler(self, signum, frame):
+        # save
+        print("bypassing sigterm")
+
+    # --------------------
+    # MODEL SAVE CHECKPOINT
+    # --------------------
+    def save_checkpoint(self, filepath):
+        checkpoint = self.dump_checkpoint()
+
+        # do the actual save
+        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:
+            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
+
+        # 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 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 restore_hpc_weights_if_needed(self, model):
+        """
+        If there is a set of hpc weights, use as signal to restore model
+        :param model:
+        :return:
+        """
+        # 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)
+
+    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)
+
+            # 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
+        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)
+
+        print(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
@@ -8,7 +8,7 @@ import os

 def add_default_args(parser, root_dir, rand_seed=None, possible_model_names=None):

-    # tng, test, val check intervals
+    # 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,
@@ -19,7 +19,7 @@ def add_default_args(parser, root_dir, rand_seed=None, possible_model_names=None
    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')
+                        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,
@@ -29,7 +29,7 @@ def add_default_args(parser, root_dir, rand_seed=None, possible_model_names=None
                        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,
+    parser.add_argument('--row_log_interval', default=100, type=int,
                        help='add log every k batches')

    # early stopping
@@ -40,7 +40,7 @@ def add_default_args(parser, root_dir, rand_seed=None, possible_model_names=None
                        help='number of epochs until stop')

    # gradient handling
-    parser.add_argument('--gradient_clip', default=-1, type=int)
+    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')

@@ -78,9 +78,9 @@ def add_default_args(parser, root_dir, rand_seed=None, possible_model_names=None
    # 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')
+                        help='runs validation after 1 training step')
    parser.add_argument('--enable_tqdm', dest='enable_tqdm', default=False, action='store_true',
-                        help='false removes the prog bar')
+                        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')

@@ -93,7 +93,7 @@ def add_default_args(parser, root_dir, rand_seed=None, possible_model_names=None
    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')
+                        help='enables local training')

    # optimizer
    parser.add_argument('--lr_scheduler_milestones', default=None, type=str)
@@ -1,7 +1,7 @@
 scikit-learn==0.20.2
-tqdm==4.32.1
+tqdm==4.35.0
 twine==1.13.0
 numpy==1.16.4
-torch>=1.1.0
+torch>=1.2.0
 torchvision>=0.3.0
-pandas
+pandas
@@ -45,6 +45,7 @@ omit =
    tests/test_models.py
    pytorch_lightning/testing_models/lm_test_module.py
    pytorch_lightning/utilities/arg_parse.py
+    examples/templates

 [flake8]
 ignore = E731,W504,F401,F841
@@ -14,7 +14,7 @@ from setuptools import setup, find_packages
 # engineer specific practices
 setup(
    name='pytorch-lightning',
-    version='0.4.2',
+    version='0.5.1.3',
    description='The Keras for ML researchers using PyTorch',
    author='William Falcon',
    author_email='waf2107@columbia.edu',
@@ -29,9 +29,9 @@ setup(
    keywords=['deep learning', 'pytorch', 'AI'],
    python_requires='>=3.6',
    install_requires=[
-        'torch==1.2.0',
-        'tqdm',
-        'test-tube==0.6.8',
+        'torch>=1.2.0',
+        'tqdm>=4.35.0',
+        'test-tube>=0.6.9',
        'pandas>=0.20.3',
    ],
    classifiers=[
@@ -51,7 +51,6 @@ setup(
        # Specify the Python versions you support here. In particular, ensure
        # that you indicate whether you support Python 2, Python 3 or both.
        'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.5',
        'Programming Language :: Python :: 3.6',
        'Programming Language :: Python :: 3.7',
    ],
@@ -1,5 +1,6 @@
 from pytorch_lightning import Trainer
 from examples import LightningTemplateModel
+from pytorch_lightning.testing import LightningTestModel
 from argparse import Namespace
 from test_tube import Experiment
 from pytorch_lightning.callbacks import ModelCheckpoint
@@ -11,6 +12,10 @@ import torch
 from torch.nn import functional as F
 from torch.utils.data import DataLoader
 from torchvision.datasets import MNIST
+import numpy as np
+import pdb
+# from test_models import assert_ok_test_acc, load_model, \
+#     clear_save_dir, get_test_tube_logger, get_hparams, init_save_dir


 class CoolModel(pl.LightningModule):
@@ -29,7 +34,7 @@ class CoolModel(pl.LightningModule):
    def training_step(self, batch, batch_nb):
        x, y = batch
        y_hat = self.forward(x)
-        return {'tng_loss': self.my_loss(y_hat, y)}
+        return {'training_loss': self.my_loss(y_hat, y)}

    def validation_step(self, batch, batch_nb):
        x, y = batch
@@ -44,7 +49,7 @@ class CoolModel(pl.LightningModule):
        return [torch.optim.Adam(self.parameters(), lr=0.02)]

    @pl.data_loader
-    def tng_dataloader(self):
+    def train_dataloader(self):
        return DataLoader(MNIST('path/to/save', train=True), batch_size=32)

    @pl.data_loader
@@ -54,123 +59,55 @@ class CoolModel(pl.LightningModule):
    @pl.data_loader
    def test_dataloader(self):
        return DataLoader(MNIST('path/to/save', train=False), batch_size=32)
+#
+#
+# def main():
+#     """
+#     Make sure DDP + AMP continue training correctly
+#     :return:
+#     """
+#     """
+#     Make sure DDP2 works
+#     :return:
+#     """
+#     hparams = get_hparams()
+#     model = LightningTestModel(hparams)
+#
+#     save_dir = init_save_dir()
+#
+#     # logger file to get meta
+#     logger = get_test_tube_logger(False)
+#     logger.log_hyperparams(hparams)
+#     logger.save()
+#
+#     # logger file to get weights
+#     checkpoint = ModelCheckpoint(save_dir)
+#
+#     trainer_options = dict(
+#         show_progress_bar=True,
+#         max_nb_epochs=1,
+#         train_percent_check=0.4,
+#         val_percent_check=0.2,
+#         checkpoint_callback=checkpoint,
+#         logger=logger,
+#         gpus=[0, 1],
+#         distributed_backend='dp'
+#     )
+#
+#     # fit model
+#     trainer = Trainer(**trainer_options)
+#     result = trainer.fit(model)
+#
+#     # correct result and ok accuracy
+#     assert result == 1, 'training failed to complete'
+#     pretrained_model = load_model(logger.experiment, save_dir, module_class=LightningTestModel)
+#
+#     new_trainer = Trainer(**trainer_options)
+#     new_trainer.test(pretrained_model)
+#
+#     # test we have good test accuracy
+#     assert_ok_test_acc(new_trainer)
+#     clear_save_dir()

-
-def get_model():
-    # set up model with these hyperparams
-    root_dir = os.path.dirname(os.path.realpath(__file__))
-    hparams = Namespace(**{'drop_prob': 0.2,
-                           'batch_size': 32,
-                           'in_features': 28 * 28,
-                           'learning_rate': 0.001 * 8,
-                           'optimizer_name': 'adam',
-                           'data_root': os.path.join(root_dir, 'mnist'),
-                           'out_features': 10,
-                           'hidden_dim': 1000})
-    model = LightningTemplateModel(hparams)
-
-    return model, hparams
-
-
-def get_exp(debug=True):
-    # set up exp object without actually saving logs
-    root_dir = os.path.dirname(os.path.realpath(__file__))
-    exp = Experiment(debug=debug, save_dir=root_dir, name='tests_tt_dir')
-    return exp
-
-
-def init_save_dir():
-    root_dir = os.path.dirname(os.path.realpath(__file__))
-    save_dir = os.path.join(root_dir, 'save_dir')
-
-    if os.path.exists(save_dir):
-        shutil.rmtree(save_dir)
-
-    os.makedirs(save_dir, exist_ok=True)
-
-    return save_dir
-
-
-def clear_save_dir():
-    root_dir = os.path.dirname(os.path.realpath(__file__))
-    save_dir = os.path.join(root_dir, 'save_dir')
-    if os.path.exists(save_dir):
-        shutil.rmtree(save_dir)
-
-
-def load_model(exp, save_dir):
-
-    # load trained model
-    tags_path = exp.get_data_path(exp.name, exp.version)
-    tags_path = os.path.join(tags_path, 'meta_tags.csv')
-
-    checkpoints = [x for x in os.listdir(save_dir) if '.ckpt' in x]
-    weights_dir = os.path.join(save_dir, checkpoints[0])
-
-    trained_model = LightningTemplateModel.load_from_metrics(weights_path=weights_dir,
-                                                             tags_csv=tags_path, on_gpu=True)
-
-    assert trained_model is not None, 'loading model failed'
-
-    return trained_model
-
-
-def run_prediction(dataloader, trained_model):
-    # run prediction on 1 batch
-    for batch in dataloader:
-        break
-
-    x, y = batch
-    x = x.view(x.size(0), -1)
-
-    y_hat = trained_model(x)
-
-    # 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)
-    val_acc = val_acc.item()
-
-    print(val_acc)
-
-    assert val_acc > 0.70, 'this model is expected to get > 0.7 in test set (it got %f)' % val_acc
-
-
-def main():
-
-    save_dir = init_save_dir()
-
-    # exp file to get meta
-    exp = get_exp(False)
-    exp.save()
-
-    # exp file to get weights
-    checkpoint = ModelCheckpoint(save_dir)
-
-    trainer = Trainer(
-        experiment=exp,
-        checkpoint_callback=checkpoint,
-        progress_bar=True,
-        max_nb_epochs=1,
-        gpus=[0, 1],
-        distributed_backend='dp',
-    )
-
-    model = CoolModel()
-
-    result = trainer.fit(model)
-
-    # correct result and ok accuracy
-    assert result == 1, 'amp + ddp model failed to complete'
-
-    # test model loading
-    pretrained_model = load_model(exp, save_dir)
-
-    # test model preds
-    run_prediction(model.test_dataloader, pretrained_model)
-
-    clear_save_dir()
-
-
-if __name__ == '__main__':
-    main()
+# if __name__ == '__main__':
+#     main()
@@ -5,4 +5,5 @@ pytest>=3.0.5
 pytest-cov
 flake8
 check-manifest
-test_tube
+test_tube
+mlflow
@@ -0,0 +1,140 @@
+import os.path
+import pickle
+import shutil
+
+import numpy as np
+import torch
+from pytorch_lightning import Trainer
+
+from pytorch_lightning.testing import LightningTestModel
+from .test_models import get_hparams, get_test_tube_logger, init_save_dir, clear_save_dir
+
+RANDOM_SEEDS = list(np.random.randint(0, 10000, 1000))
+
+
+def test_testtube_logger():
+    """
+    verify that basic functionality of test tube logger works
+    """
+    reset_seed()
+
+    hparams = get_hparams()
+    model = LightningTestModel(hparams)
+
+    save_dir = init_save_dir()
+
+    logger = get_test_tube_logger(False)
+
+    trainer_options = dict(
+        max_nb_epochs=1,
+        train_percent_check=0.01,
+        logger=logger
+    )
+
+    trainer = Trainer(**trainer_options)
+    result = trainer.fit(model)
+
+    assert result == 1, "Training failed"
+
+    clear_save_dir()
+
+
+def test_testtube_pickle():
+    """
+    Verify that pickling a trainer containing a test tube logger works
+    """
+    reset_seed()
+
+    hparams = get_hparams()
+    model = LightningTestModel(hparams)
+
+    save_dir = init_save_dir()
+
+    logger = get_test_tube_logger(False)
+    logger.log_hyperparams(hparams)
+    logger.save()
+
+    trainer_options = dict(
+        max_nb_epochs=1,
+        train_percent_check=0.01,
+        logger=logger
+    )
+
+    trainer = Trainer(**trainer_options)
+    pkl_bytes = pickle.dumps(trainer)
+    trainer2 = pickle.loads(pkl_bytes)
+    trainer2.logger.log_metrics({"acc": 1.0})
+
+
+def test_mlflow_logger():
+    """
+    verify that basic functionality of mlflow logger works
+    """
+    reset_seed()
+
+    try:
+        from pytorch_lightning.logging import MLFlowLogger
+    except ModuleNotFoundError:
+        return
+
+    hparams = get_hparams()
+    model = LightningTestModel(hparams)
+
+    root_dir = os.path.dirname(os.path.realpath(__file__))
+    mlflow_dir = os.path.join(root_dir, "mlruns")
+
+    logger = MLFlowLogger("test", f"file://{mlflow_dir}")
+    logger.log_hyperparams(hparams)
+    logger.save()
+
+    trainer_options = dict(
+        max_nb_epochs=1,
+        train_percent_check=0.01,
+        logger=logger
+    )
+
+    trainer = Trainer(**trainer_options)
+    result = trainer.fit(model)
+
+    assert result == 1, "Training failed"
+
+    n = np.random.randint(0, 10000000, 1)[0]
+    shutil.move(mlflow_dir, mlflow_dir + f'_{n}')
+
+
+def test_mlflow_pickle():
+    """
+    verify that pickling trainer with mlflow logger works
+    """
+    reset_seed()
+
+    try:
+        from pytorch_lightning.logging import MLFlowLogger
+    except ModuleNotFoundError:
+        return
+
+    hparams = get_hparams()
+    model = LightningTestModel(hparams)
+
+    root_dir = os.path.dirname(os.path.realpath(__file__))
+    mlflow_dir = os.path.join(root_dir, "mlruns")
+
+    logger = MLFlowLogger("test", f"file://{mlflow_dir}")
+    logger.log_hyperparams(hparams)
+    logger.save()
+
+    trainer_options = dict(
+        max_nb_epochs=1,
+        logger=logger
+    )
+
+    trainer = Trainer(**trainer_options)
+    pkl_bytes = pickle.dumps(trainer)
+    trainer2 = pickle.loads(pkl_bytes)
+    trainer2.logger.log_metrics({"acc": 1.0})
+
+
+def reset_seed():
+    SEED = RANDOM_SEEDS.pop()
+    torch.manual_seed(SEED)
+    np.random.seed(SEED)
@@ -34,11 +34,11 @@ deps =
 commands =
    check-manifest --ignore tox.ini
    python setup.py check -m -s
-    coverage run --source pytorch_lightning -m py.test pytorch_lightning tests examples -v --doctest-modules
    flake8 .
+    coverage run --source pytorch_lightning -m py.test pytorch_lightning tests examples -v --doctest-modules

 [flake8]
-exclude = .tox,*.egg,build,temp
+exclude = .tox,*.egg,build,temp,examples/*
 select = E,W,F
 doctests = True
 verbose = 2