Source code for ray.train.data_parallel_trainer

import inspect
import logging
from pathlib import Path
from typing import TYPE_CHECKING, Any, Callable, Dict, Optional, Tuple, Type, Union
from tabulate import tabulate

import ray
from ray import tune
from ray.air import session
from ray.air.checkpoint import Checkpoint
from ray.air._internal.checkpointing import save_preprocessor_to_dir
from ray.air.config import DatasetConfig, RunConfig, ScalingConfig, CheckpointConfig
from ray.air.constants import MODEL_KEY, PREPROCESSOR_KEY
from ray.air._internal.checkpoint_manager import _TrackedCheckpoint
from ray.train import BackendConfig, TrainingIterator
from ray.train._internal.backend_executor import BackendExecutor, TrialInfo
from ray.train._internal.checkpoint import TuneCheckpointManager
from ray.train._internal.dataset_spec import DataParallelIngestSpec
from ray.train._internal.utils import construct_train_func
from ray.train.constants import TRAIN_DATASET_KEY, WILDCARD_KEY
from ray.train.trainer import BaseTrainer, GenDataset
from ray.util.annotations import DeveloperAPI
from ray.widgets import Template
from ray.widgets.util import ensure_notebook_deps

if TYPE_CHECKING:
    from ray.data.preprocessor import Preprocessor

logger = logging.getLogger(__name__)


# TODO(team-ml): Refactor checkpoint management along with Tune.
class _DataParallelCheckpointManager(TuneCheckpointManager):
    def __init__(
        self,
        preprocessor: "Preprocessor",
        run_dir: Optional[Path] = None,
        checkpoint_strategy: Optional[CheckpointConfig] = None,
    ):
        self.preprocessor = preprocessor
        super(_DataParallelCheckpointManager, self).__init__(
            run_dir=run_dir, checkpoint_strategy=checkpoint_strategy
        )

    def _process_persistent_checkpoint(self, checkpoint: _TrackedCheckpoint):
        if isinstance(checkpoint.dir_or_data, dict):
            checkpoint.dir_or_data[PREPROCESSOR_KEY] = self.preprocessor
        else:
            save_preprocessor_to_dir(self.preprocessor, checkpoint.dir_or_data)
        super(_DataParallelCheckpointManager, self)._process_persistent_checkpoint(
            checkpoint=checkpoint
        )


[docs]@DeveloperAPI class DataParallelTrainer(BaseTrainer): """A Trainer for data parallel training. You should subclass this Trainer if your Trainer follows SPMD (single program, multiple data) programming paradigm - you want multiple processes to run the same function, but on different data. This Trainer runs the function ``train_loop_per_worker`` on multiple Ray Actors. The ``train_loop_per_worker`` function is expected to take in either 0 or 1 arguments: .. code-block:: python def train_loop_per_worker(): ... .. code-block:: python def train_loop_per_worker(config: Dict): ... If ``train_loop_per_worker`` accepts an argument, then ``train_loop_config`` will be passed in as the argument. This is useful if you want to tune the values in ``train_loop_config`` as hyperparameters. If the ``datasets`` dict contains a training dataset (denoted by the "train" key), then it will be split into multiple dataset shards that can then be accessed by ``session.get_dataset_shard("train")`` inside ``train_loop_per_worker``. All the other datasets will not be split and ``session.get_dataset_shard(...)`` will return the the entire Dataset. Inside the ``train_loop_per_worker`` function, you can use any of the :ref:`Ray AIR session methods <air-session-ref>`. .. code-block:: python def train_loop_per_worker(): # Report intermediate results for callbacks or logging and # checkpoint data. session.report(...) # Returns dict of last saved checkpoint. session.get_checkpoint() # Returns the Ray Dataset shard for the given key. session.get_dataset_shard("my_dataset") # Returns the total number of workers executing training. session.get_world_size() # Returns the rank of this worker. session.get_world_rank() # Returns the rank of the worker on the current node. session.get_local_rank() Any returns from the ``train_loop_per_worker`` will be discarded and not used or persisted anywhere. **How do I use ``DataParallelTrainer`` or any of its subclasses?** Example: .. code-block:: python import ray from ray.air import session def train_loop_for_worker(): dataset_shard_for_this_worker = session.get_dataset_shard("train") assert len(dataset_shard_for_this_worker) == 1 train_dataset = ray.data.from_items([1, 2, 3]) assert len(train_dataset) == 3 trainer = DataParallelTrainer( ray.air.config.ScalingConfig(num_workers=3), datasets={"train": train_dataset}, ) result = trainer.fit() **How do I develop on top of ``DataParallelTrainer``?** In many cases, using DataParallelTrainer directly is sufficient to execute functions on multiple actors. However, you may want to subclass ``DataParallelTrainer`` and create a custom Trainer for the following 2 use cases: - **Use Case 1:** You want to do data parallel training, but want to have a predefined ``training_loop_per_worker``. - **Use Case 2:** You want to implement a custom :py:class:`~ray.train.backend.Backend` that automatically handles additional setup or teardown logic on each actor, so that the users of this new trainer do not have to implement this logic. For example, a ``TensorflowTrainer`` can be built on top of ``DataParallelTrainer`` that automatically handles setting the proper environment variables for distributed Tensorflow on each actor. For 1, you can set a predefined training loop in __init__ .. code-block:: python from ray.train.data_parallel_trainer import DataParallelTrainer class MyDataParallelTrainer(DataParallelTrainer): def __init__(self, *args, **kwargs): predefined_train_loop_per_worker = lambda: 1 super().__init__(predefined_train_loop_per_worker, *args, **kwargs) For 2, you can implement the ``ray.train.Backend`` and ``ray.train.BackendConfig`` interfaces. .. code-block:: python from dataclasses import dataclass from ray.train.backend import Backend, BackendConfig class MyBackend(Backend): def on_start(self, worker_group, backend_config): def set_env_var(env_var_value): import os os.environ["MY_ENV_VAR"] = env_var_value worker_group.execute(set_env_var, backend_config.env_var) @dataclass class MyBackendConfig(BackendConfig): env_var: str = "default_value" def backend_cls(self): return MyBackend class MyTrainer(DataParallelTrainer): def __init__(self, train_loop_per_worker, my_backend_config: MyBackendConfig, **kwargs): super().__init__( train_loop_per_worker, backend_config=my_backend_config, **kwargs) Args: train_loop_per_worker: The training function to execute. This can either take in no arguments or a ``config`` dict. train_loop_config: Configurations to pass into ``train_loop_per_worker`` if it accepts an argument. backend_config: Configuration for setting up a Backend (e.g. Torch, Tensorflow, Horovod) on each worker to enable distributed communication. If no Backend should be set up, then set this to None. scaling_config: Configuration for how to scale data parallel training. dataset_config: Configuration for dataset ingest. This is merged with the default dataset config for the given trainer (`cls._dataset_config`). run_config: Configuration for the execution of the training run. datasets: Any Ray Datasets to use for training. Use the key "train" to denote which dataset is the training dataset. If a ``preprocessor`` is provided and has not already been fit, it will be fit on the training dataset. All datasets will be transformed by the ``preprocessor`` if one is provided. preprocessor: A ray.data.Preprocessor to preprocess the provided datasets. resume_from_checkpoint: A checkpoint to resume training from. """ _checkpoint_manager_cls: Type[ TuneCheckpointManager ] = _DataParallelCheckpointManager # Exposed here for testing purposes. Should never need # to be overriden. _backend_executor_cls: Type[BackendExecutor] = BackendExecutor _training_iterator_cls: Type[TrainingIterator] = TrainingIterator _scaling_config_allowed_keys = BaseTrainer._scaling_config_allowed_keys + [ "num_workers", "resources_per_worker", "use_gpu", "placement_strategy", ] _dataset_config = { TRAIN_DATASET_KEY: DatasetConfig(fit=True, split=True), WILDCARD_KEY: DatasetConfig(split=False), }
[docs] def __init__( self, train_loop_per_worker: Union[Callable[[], None], Callable[[Dict], None]], *, train_loop_config: Optional[Dict] = None, backend_config: Optional[BackendConfig] = None, scaling_config: Optional[ScalingConfig] = None, dataset_config: Optional[Dict[str, DatasetConfig]] = None, run_config: Optional[RunConfig] = None, datasets: Optional[Dict[str, GenDataset]] = None, preprocessor: Optional["Preprocessor"] = None, resume_from_checkpoint: Optional[Checkpoint] = None, ): if not ray.is_initialized(): ray.init() self._train_loop_per_worker = train_loop_per_worker self._train_loop_config = train_loop_config backend_config = ( backend_config if backend_config is not None else BackendConfig() ) self._backend_config = backend_config self._dataset_config = DatasetConfig.validated( DatasetConfig.merge(self._dataset_config, dataset_config), datasets ) self._ingest_spec = DataParallelIngestSpec( dataset_config=self._dataset_config, ) super(DataParallelTrainer, self).__init__( scaling_config=scaling_config, run_config=run_config, datasets=datasets, preprocessor=preprocessor, resume_from_checkpoint=resume_from_checkpoint, )
def _validate_attributes(self): super()._validate_attributes() if not self.scaling_config.use_gpu and "GPU" in ray.available_resources(): logger.info( "GPUs are detected in your Ray cluster, but GPU " "training is not enabled for this trainer. To enable " "GPU training, make sure to set `use_gpu` to True " "in your scaling config." ) if self.scaling_config.num_workers is None: raise ValueError("You must specify the 'num_workers' in scaling_config.") if self.scaling_config.num_workers <= 0: raise ValueError( "'num_workers' in `scaling_config` must be a positive " f"integer. Received {self.scaling_config.num_workers}" ) self._validate_train_loop_per_worker( self._train_loop_per_worker, "train_loop_per_worker" )
[docs] def preprocess_datasets(self) -> None: # Evaluate all datasets. self.datasets = {k: d() if callable(d) else d for k, d in self.datasets.items()} self.datasets = self._ingest_spec.preprocess_datasets( self.preprocessor, self.datasets )
def _validate_train_loop_per_worker( self, train_loop_per_worker: Callable, fn_name: str ) -> None: num_params = len(inspect.signature(train_loop_per_worker).parameters) if num_params > 1: raise ValueError( f"{fn_name} should take in 0 or 1 arguments, " f"but it accepts {num_params} arguments instead." ) def _report(self, training_iterator: TrainingIterator) -> None: for results in training_iterator: # TODO(ml-team): add ability to report results from multiple workers. first_worker_results = results[0] tune.report(**first_worker_results)
[docs] def training_loop(self) -> None: scaling_config = self._validate_scaling_config(self.scaling_config) train_loop_per_worker = construct_train_func( self._train_loop_per_worker, self._train_loop_config, fn_arg_name="train_loop_per_worker", discard_returns=True, ) additional_resources_per_worker = scaling_config.additional_resources_per_worker trial_info = TrialInfo( name=session.get_trial_name(), id=session.get_trial_id(), resources=session.get_trial_resources(), logdir=session.get_trial_dir(), experiment_name=session.get_experiment_name(), ) backend_executor = self._backend_executor_cls( backend_config=self._backend_config, trial_info=trial_info, num_workers=scaling_config.num_workers, num_cpus_per_worker=scaling_config.num_cpus_per_worker, num_gpus_per_worker=scaling_config.num_gpus_per_worker, additional_resources_per_worker=additional_resources_per_worker, max_retries=0, ) checkpoint_manager = self._checkpoint_manager_cls( preprocessor=self.preprocessor ) # Start the remote actors. backend_executor.start(initialization_hook=None) training_iterator = self._training_iterator_cls( backend_executor=backend_executor, backend_config=self._backend_config, train_func=train_loop_per_worker, dataset_spec=self._ingest_spec, checkpoint_manager=checkpoint_manager, checkpoint=self.resume_from_checkpoint, checkpoint_strategy=None, ) self._report(training_iterator) # Shutdown workers. backend_executor.shutdown()
[docs] def get_dataset_config(self) -> Dict[str, DatasetConfig]: """Return a copy of this Trainer's final dataset configs. Returns: The merged default + user-supplied dataset config. """ return self._dataset_config.copy()
@ensure_notebook_deps( ["tabulate", None], ["ipywidgets", "8"], ) def _ipython_display_(self): from ipywidgets import HTML, VBox, Tab, Layout from IPython.display import display title = HTML(f"<h2>{self.__class__.__name__}</h2>") children = [ self._datasets_repr_() if self.datasets else None, HTML(self._dataset_config_repr_html_()) if self._dataset_config else None, HTML(self._train_loop_config_repr_html_()) if self._train_loop_config else None, HTML(self.scaling_config._repr_html_()) if self.scaling_config else None, HTML(self.run_config._repr_html_()) if self.run_config else None, HTML(self._backend_config._repr_html_()) if self._backend_config else None, ] tab = Tab( children, titles=[ "Datasets", "Dataset Config", "Train Loop Config", "Scaling Config", "Run Config", "Backend Config", ], ) display(VBox([title, tab], layout=Layout(width="100%"))) def _train_loop_config_repr_html_(self) -> str: if self._train_loop_config: table_data = {} for k, v in self._train_loop_config.items(): if isinstance(v, str) or str(v).isnumeric(): table_data[k] = v elif hasattr(v, "_repr_html_"): table_data[k] = v._repr_html_() else: table_data[k] = str(v) return Template("title_data.html.j2").render( title="Train Loop Config", data=Template("scrollableTable.html.j2").render( table=tabulate( table_data.items(), headers=["Setting", "Value"], showindex=False, tablefmt="unsafehtml", ), max_height="none", ), ) else: return "" def _dataset_config_repr_html_(self) -> str: content = [] if self._dataset_config: for name, config in self._dataset_config.items(): content.append( config._repr_html_(title=f"DatasetConfig - <code>{name}</code>") ) return Template("rendered_html_common.html.j2").render(content=content) @ensure_notebook_deps(["ipywidgets", "8"]) def _datasets_repr_(self) -> str: from ipywidgets import HTML, VBox, Layout content = [] if self.datasets: for name, config in self.datasets.items(): tab = config._tab_repr_() if tab: content.append( HTML( Template("title_data.html.j2").render( title=f"Dataset - <code>{name}</code>", data=None ) ) ) content.append(config._tab_repr_()) return VBox(content, layout=Layout(width="100%"))
def _load_checkpoint_dict( checkpoint: Checkpoint, trainer_name: str ) -> Tuple[Any, Optional["Preprocessor"]]: """Load a Ray Train Checkpoint (dict based). This is a private API. Args: checkpoint: The checkpoint to load the weights and preprocessor from. trainer_name: Trainer class name to use in error message. Returns: The model or weights and AIR preprocessor contained within. """ checkpoint_dict = checkpoint.to_dict() preprocessor = checkpoint_dict.get(PREPROCESSOR_KEY, None) if MODEL_KEY not in checkpoint_dict: raise RuntimeError( f"No item with key: {MODEL_KEY} is found in the " f"Checkpoint. Make sure this key exists when saving the " f"checkpoint in ``{trainer_name}``." ) model = checkpoint_dict[MODEL_KEY] return model, preprocessor