Source code for lightning.fabric.strategies.dp

# Copyright The Lightning AI team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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from typing import Any, Dict, List, Optional, Union

import torch
from torch import Tensor
from torch.nn import DataParallel, Module
from typing_extensions import override

from lightning.fabric.accelerators import Accelerator
from lightning.fabric.plugins.io.checkpoint_io import CheckpointIO
from lightning.fabric.plugins.precision import Precision
from lightning.fabric.strategies.parallel import ParallelStrategy
from lightning.fabric.strategies.registry import _StrategyRegistry
from lightning.fabric.strategies.strategy import TBroadcast, TReduce
from lightning.fabric.utilities.apply_func import apply_to_collection
from lightning.fabric.utilities.distributed import ReduceOp


[docs]class DataParallelStrategy(ParallelStrategy): """Implements data-parallel training in a single process, i.e., the model gets replicated to each device and each gets a split of the data.""" def __init__( self, accelerator: Optional[Accelerator] = None, parallel_devices: Optional[List[torch.device]] = None, checkpoint_io: Optional[CheckpointIO] = None, precision: Optional[Precision] = None, ): super().__init__( accelerator=accelerator, parallel_devices=parallel_devices, cluster_environment=None, checkpoint_io=checkpoint_io, precision=precision, ) @property @override def root_device(self) -> torch.device: assert self.parallel_devices is not None return self.parallel_devices[0] @property @override def distributed_sampler_kwargs(self) -> None: return None
[docs] @override def setup_module(self, module: Module) -> DataParallel: """Wraps the given model into a :class:`~torch.nn.DataParallel` module.""" return DataParallel(module=module, device_ids=self.parallel_devices)
[docs] @override def module_to_device(self, module: Module) -> None: module.to(self.root_device)
[docs] @override def batch_to_device(self, batch: Any, device: Optional[torch.device] = None) -> Any: # DataParallel handles the transfer of batch to the device return batch
[docs] @override def all_reduce( self, collection: TReduce, group: Optional[Any] = None, reduce_op: Optional[Union[ReduceOp, str]] = "mean" ) -> TReduce: def mean(t: Tensor) -> Tensor: original_dtype = t.dtype return t.float().mean().to(original_dtype) return apply_to_collection(collection, Tensor, mean)
[docs] @override def barrier(self, *args: Any, **kwargs: Any) -> None: pass
[docs] @override def broadcast(self, obj: TBroadcast, src: int = 0) -> TBroadcast: return obj
[docs] @override def reduce_boolean_decision(self, decision: bool, all: bool = True) -> bool: return decision
[docs] @override def get_module_state_dict(self, module: Module) -> Dict[str, Union[Any, Tensor]]: if isinstance(module, DataParallel): module = module.module return super().get_module_state_dict(module)
[docs] @override def load_module_state_dict( self, module: Module, state_dict: Dict[str, Union[Any, Tensor]], strict: bool = True ) -> None: if isinstance(module, DataParallel): module = module.module super().load_module_state_dict(module=module, state_dict=state_dict, strict=strict)
@classmethod @override def register_strategies(cls, strategy_registry: _StrategyRegistry) -> None: strategy_registry.register("dp", cls, description=cls.__name__)