Files
ray/python/ray/tune/suggest/suggestion.py
T

313 lines
11 KiB
Python

import copy
import glob
import logging
import os
from ray.util.debug import log_once
logger = logging.getLogger(__name__)
class Searcher:
"""Abstract class for wrapping suggesting algorithms.
Custom algorithms can extend this class easily by overriding the
`suggest` method provide generated parameters for the trials.
Any subclass that implements ``__init__`` must also call the
constructor of this class: ``super(Subclass, self).__init__(...)``.
To track suggestions and their corresponding evaluations, the method
`suggest` will be passed a trial_id, which will be used in
subsequent notifications.
Args:
metric (str): The training result objective value attribute.
mode (str): One of {min, max}. Determines whether objective is
minimizing or maximizing the metric attribute.
.. code-block:: python
class ExampleSearch(Searcher):
def __init__(self, metric="mean_loss", mode="min", **kwargs):
super(ExampleSearch, self).__init__(
metric=metric, mode=mode, **kwargs)
self.optimizer = Optimizer()
self.configurations = {}
def suggest(self, trial_id):
configuration = self.optimizer.query()
self.configurations[trial_id] = configuration
def on_trial_complete(self, trial_id, result, **kwargs):
configuration = self.configurations[trial_id]
if result and self.metric in result:
self.optimizer.update(configuration, result[self.metric])
tune.run(trainable_function, search_alg=ExampleSearch())
"""
FINISHED = "FINISHED"
CKPT_FILE_TMPL = "searcher-state-{}.pkl"
def __init__(self,
metric="episode_reward_mean",
mode="max",
max_concurrent=None,
use_early_stopped_trials=None):
if use_early_stopped_trials is False:
raise DeprecationWarning(
"Early stopped trials are now always used. If this is a "
"problem, file an issue: https://github.com/ray-project/ray.")
if max_concurrent is not None:
logger.warning(
"DeprecationWarning: `max_concurrent` is deprecated for this "
"search algorithm. Use tune.suggest.ConcurrencyLimiter() "
"instead. This will raise an error in future versions of Ray.")
assert mode in ["min", "max"], "`mode` must be 'min' or 'max'!"
self._metric = metric
self._mode = mode
def on_trial_result(self, trial_id, result):
"""Optional notification for result during training.
Note that by default, the result dict may include NaNs or
may not include the optimization metric. It is up to the
subclass implementation to preprocess the result to
avoid breaking the optimization process.
Args:
trial_id (str): A unique string ID for the trial.
result (dict): Dictionary of metrics for current training progress.
Note that the result dict may include NaNs or
may not include the optimization metric. It is up to the
subclass implementation to preprocess the result to
avoid breaking the optimization process.
"""
pass
def on_trial_complete(self, trial_id, result=None, error=False):
"""Notification for the completion of trial.
Typically, this method is used for notifying the underlying
optimizer of the result.
Args:
trial_id (str): A unique string ID for the trial.
result (dict): Dictionary of metrics for current training progress.
Note that the result dict may include NaNs or
may not include the optimization metric. It is up to the
subclass implementation to preprocess the result to
avoid breaking the optimization process. Upon errors, this
may also be None.
error (bool): True if the training process raised an error.
"""
raise NotImplementedError
def suggest(self, trial_id):
"""Queries the algorithm to retrieve the next set of parameters.
Arguments:
trial_id (str): Trial ID used for subsequent notifications.
Returns:
dict | FINISHED | None: Configuration for a trial, if possible.
If FINISHED is returned, Tune will be notified that
no more suggestions/configurations will be provided.
If None is returned, Tune will skip the querying of the
searcher for this step.
"""
raise NotImplementedError
def save(self, checkpoint_path):
"""Save state to path for this search algorithm.
Args:
checkpoint_path (str): File where the search algorithm
state is saved. This path should be used later when
restoring from file.
Example:
.. code-block:: python
search_alg = Searcher(...)
analysis = tune.run(
cost,
num_samples=5,
search_alg=search_alg,
name=self.experiment_name,
local_dir=self.tmpdir)
search_alg.save("./my_favorite_path.pkl")
.. versionchanged:: 0.8.7
Save is automatically called by `tune.run`. You can use
`restore_from_dir` to restore from an experiment directory
such as `~/ray_results/trainable`.
"""
raise NotImplementedError
def restore(self, checkpoint_path):
"""Restore state for this search algorithm
Args:
checkpoint_path (str): File where the search algorithm
state is saved. This path should be the same
as the one provided to "save".
Example:
.. code-block:: python
search_alg.save("./my_favorite_path.pkl")
search_alg2 = Searcher(...)
search_alg2 = ConcurrencyLimiter(search_alg2, 1)
search_alg2.restore(checkpoint_path)
tune.run(cost, num_samples=5, search_alg=search_alg2)
"""
raise NotImplementedError
def get_state(self):
raise NotImplementedError
def set_state(self, state):
raise NotImplementedError
def save_to_dir(self, checkpoint_dir, session_str="default"):
"""Automatically saves the given searcher to the checkpoint_dir.
This is automatically used by tune.run during a Tune job.
Args:
checkpoint_dir (str): Filepath to experiment dir.
session_str (str): Unique identifier of the current run
session.
"""
tmp_search_ckpt_path = os.path.join(checkpoint_dir,
".tmp_searcher_ckpt")
success = True
try:
self.save(tmp_search_ckpt_path)
except NotImplementedError:
if log_once("suggest:save_to_dir"):
logger.warning(
"save not implemented for Searcher. Skipping save.")
success = False
if success and os.path.exists(tmp_search_ckpt_path):
os.rename(
tmp_search_ckpt_path,
os.path.join(checkpoint_dir,
self.CKPT_FILE_TMPL.format(session_str)))
def restore_from_dir(self, checkpoint_dir):
"""Restores the state of a searcher from a given checkpoint_dir.
Typically, you should use this function to restore from an
experiment directory such as `~/ray_results/trainable`.
.. code-block:: python
experiment_1 = tune.run(
cost,
num_samples=5,
search_alg=search_alg,
verbose=0,
name=self.experiment_name,
local_dir="~/my_results")
search_alg2 = Searcher()
search_alg2.restore_from_dir(
os.path.join("~/my_results", self.experiment_name)
"""
pattern = self.CKPT_FILE_TMPL.format("*")
full_paths = glob.glob(os.path.join(checkpoint_dir, pattern))
if not full_paths:
raise RuntimeError(
"Searcher unable to find checkpoint in {}".format(
checkpoint_dir)) # TODO
most_recent_checkpoint = max(full_paths)
self.restore(most_recent_checkpoint)
@property
def metric(self):
"""The training result objective value attribute."""
return self._metric
@property
def mode(self):
"""Specifies if minimizing or maximizing the metric."""
return self._mode
class ConcurrencyLimiter(Searcher):
"""A wrapper algorithm for limiting the number of concurrent trials.
Args:
searcher (Searcher): Searcher object that the
ConcurrencyLimiter will manage.
Example:
.. code-block:: python
from ray.tune.suggest import ConcurrencyLimiter
search_alg = HyperOptSearch(metric="accuracy")
search_alg = ConcurrencyLimiter(search_alg, max_concurrent=2)
tune.run(trainable, search_alg=search_alg)
"""
def __init__(self, searcher, max_concurrent):
assert type(max_concurrent) is int and max_concurrent > 0
self.searcher = searcher
self.max_concurrent = max_concurrent
self.live_trials = set()
super(ConcurrencyLimiter, self).__init__(
metric=self.searcher.metric, mode=self.searcher.mode)
def suggest(self, trial_id):
assert trial_id not in self.live_trials, (
f"Trial ID {trial_id} must be unique: already found in set.")
if len(self.live_trials) >= self.max_concurrent:
logger.debug(
f"Not providing a suggestion for {trial_id} due to "
"concurrency limit: %s/%s.", len(self.live_trials),
self.max_concurrent)
return
suggestion = self.searcher.suggest(trial_id)
if suggestion not in (None, Searcher.FINISHED):
self.live_trials.add(trial_id)
return suggestion
def on_trial_complete(self, trial_id, result=None, error=False):
if trial_id not in self.live_trials:
return
else:
self.searcher.on_trial_complete(
trial_id, result=result, error=error)
self.live_trials.remove(trial_id)
def get_state(self):
state = self.__dict__.copy()
del state["searcher"]
return copy.deepcopy(state)
def set_state(self, state):
self.__dict__.update(state)
def on_pause(self, trial_id):
self.searcher.on_pause(trial_id)
def on_unpause(self, trial_id):
self.searcher.on_unpause(trial_id)