Source code for pytorch_lightning.strategies.single_device

# 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
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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from __future__ import annotations

from typing import Any

import torch
from torch import Tensor

import pytorch_lightning as pl
from lightning_fabric.plugins import CheckpointIO
from lightning_fabric.utilities.types import _DEVICE
from pytorch_lightning.plugins.precision import PrecisionPlugin
from pytorch_lightning.strategies.strategy import Strategy, TBroadcast

[docs]class SingleDeviceStrategy(Strategy): """Strategy that handles communication on a single device.""" strategy_name = "single_device" def __init__( self, device: _DEVICE = "cpu", accelerator: pl.accelerators.accelerator.Accelerator | None = None, checkpoint_io: CheckpointIO | None = None, precision_plugin: PrecisionPlugin | None = None, ): super().__init__(accelerator=accelerator, checkpoint_io=checkpoint_io, precision_plugin=precision_plugin) self._root_device = torch.device(device) self.global_rank = 0 self.local_rank = 0 self.world_size = 1
[docs] def reduce(self, tensor: Any | Tensor, *args: Any, **kwargs: Any) -> Any | Tensor: """Reduces a tensor from several distributed processes to one aggregated tensor. As this plugin only operates with a single device, the reduction is simply the identity. Args: tensor: the tensor to sync and reduce *args: ignored **kwargs: ignored Return: the unmodified input as reduction is not needed for single process operation """ return tensor
[docs] def all_gather(self, tensor: Tensor, group: Any | None = None, sync_grads: bool = False) -> Tensor: """Perform a all_gather on all processes.""" return tensor
@property def root_device(self) -> torch.device: return self._root_device
[docs] def model_to_device(self) -> None: assert self.model is not None, "self.model must be set before"
[docs] def setup(self, trainer: pl.Trainer) -> None: self.model_to_device() super().setup(trainer)
@property def is_global_zero(self) -> bool: return True
[docs] def barrier(self, *args: Any, **kwargs: Any) -> None: pass
[docs] def broadcast(self, obj: TBroadcast, src: int = 0) -> TBroadcast: return obj
@classmethod def register_strategies(cls, strategy_registry: dict) -> None: strategy_registry.register( cls.strategy_name, cls, description=f"{cls.__class__.__name__}", )

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