Source code for ray.train.horovod.horovod_trainer

from typing import Dict, Callable, Optional, Union, TYPE_CHECKING

from ray.air.config import ScalingConfig, RunConfig, DatasetConfig
from ray.train.trainer import GenDataset
from ray.air.checkpoint import Checkpoint


from ray.train.data_parallel_trainer import DataParallelTrainer
from ray.train.horovod.config import HorovodConfig
from ray.util.annotations import PublicAPI

if TYPE_CHECKING:
    from ray.data.preprocessor import Preprocessor


[docs]@PublicAPI(stability="beta") class HorovodTrainer(DataParallelTrainer): """A Trainer for data parallel Horovod training. This Trainer runs the function ``train_loop_per_worker`` on multiple Ray Actors. These actors already have the necessary Horovod setup already configured for distributed Horovod training. 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. You could use ``TensorflowPredictor`` or ``TorchPredictor`` in conjunction with HorovodTrainer. You must save the model under the "model" kwarg in the ``Checkpoint`` passed to ``session.report()``, so that it can be used by corresponding predictors. Example: .. code-block:: python import ray import ray.train as train import ray.train.torch. # Need this to use `train.torch.get_device()` import horovod.torch as hvd import torch import torch.nn as nn from ray.air import session from ray.train.horovod import HorovodTrainer from ray.train.torch import TorchCheckpoint from ray.air.config import ScalingConfig input_size = 1 layer_size = 15 output_size = 1 num_epochs = 3 class NeuralNetwork(nn.Module): def __init__(self): super(NeuralNetwork, self).__init__() self.layer1 = nn.Linear(input_size, layer_size) self.relu = nn.ReLU() self.layer2 = nn.Linear(layer_size, output_size) def forward(self, input): return self.layer2(self.relu(self.layer1(input))) def train_loop_per_worker(): hvd.init() dataset_shard = session.get_dataset_shard("train") model = NeuralNetwork() device = train.torch.get_device() model.to(device) loss_fn = nn.MSELoss() lr_scaler = 1 optimizer = torch.optim.SGD(model.parameters(), lr=0.1 * lr_scaler) # Horovod: wrap optimizer with DistributedOptimizer. optimizer = hvd.DistributedOptimizer( optimizer, named_parameters=model.named_parameters(), op=hvd.Average, ) for epoch in range(num_epochs): model.train() for batch in dataset_shard.iter_torch_batches( batch_size=32, dtypes=torch.float ): inputs, labels = torch.unsqueeze(batch["x"], 1), batch["y"] inputs.to(device) labels.to(device) outputs = model(inputs) loss = loss_fn(outputs, labels) optimizer.zero_grad() loss.backward() optimizer.step() print(f"epoch: {epoch}, loss: {loss.item()}") session.report( {}, checkpoint=TorchCheckpoint.from_state_dict( model.state_dict() ), ) train_dataset = ray.data.from_items([{"x": x, "y": x + 1} for x in range(32)]) scaling_config = ScalingConfig(num_workers=3) # If using GPUs, use the below scaling config instead. # scaling_config = ScalingConfig(num_workers=3, use_gpu=True) trainer = HorovodTrainer( train_loop_per_worker=train_loop_per_worker, scaling_config=scaling_config, datasets={"train": train_dataset}, ) result = trainer.fit() 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. horovod_config: Configuration for setting up the Horovod backend. If set to None, use the default configuration. This replaces the ``backend_config`` arg of ``DataParallelTrainer``. scaling_config: Configuration for how to scale data parallel training. dataset_config: Configuration for dataset ingest. 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. """
[docs] def __init__( self, train_loop_per_worker: Union[Callable[[], None], Callable[[Dict], None]], *, train_loop_config: Optional[Dict] = None, horovod_config: Optional[HorovodConfig] = 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, ): super().__init__( train_loop_per_worker=train_loop_per_worker, train_loop_config=train_loop_config, backend_config=horovod_config or HorovodConfig(), scaling_config=scaling_config, dataset_config=dataset_config, run_config=run_config, datasets=datasets, preprocessor=preprocessor, resume_from_checkpoint=resume_from_checkpoint, )