Source code for pytorch_lightning.plugins.precision.apex_amp

# Copyright The PyTorch Lightning 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,
# See the License for the specific language governing permissions and
# limitations under the License.
from typing import Any, Callable, Dict, Optional, Union

from torch import Tensor
from torch.nn import Module
from torch.optim import LBFGS, Optimizer

import pytorch_lightning as pl
from pytorch_lightning.plugins.precision.mixed import MixedPrecisionPlugin
from pytorch_lightning.utilities import _APEX_AVAILABLE, AMPType
from pytorch_lightning.utilities.exceptions import MisconfigurationException
from pytorch_lightning.utilities.types import _PARAMETERS

    from apex import amp

[docs]class ApexMixedPrecisionPlugin(MixedPrecisionPlugin): """Mixed Precision Plugin based on Nvidia/Apex (""" backend = AMPType.APEX def __init__(self, amp_level: str = "O2") -> None: if not _APEX_AVAILABLE: raise MisconfigurationException( "You have asked for Apex AMP but `apex` is not installed." " Install `apex` using this guide:" ) super().__init__() self.amp_level = amp_level self._connected = False
[docs] def main_params(self, optimizer: Optimizer) -> _PARAMETERS: return amp.master_params(optimizer)
[docs] def dispatch(self, trainer: "pl.Trainer") -> None: if not self._connected: strategy = trainer.strategy _, strategy.optimizers = amp.initialize( trainer.lightning_module, strategy.optimizers, opt_level=self.amp_level ) self._connected = True return super().dispatch(trainer)
[docs] def backward( self, model: "pl.LightningModule", closure_loss: Tensor, optimizer: Optional[Optimizer], optimizer_idx: Optional[int], *args: Any, **kwargs: Any, ) -> None: """Run before precision plugin executes backward. Args: model: the model to be optimized closure_loss: the loss value obtained from the closure optimizer: current optimizer being used. ``None`` if using manual optimization """ opt = optimizer or model.trainer.optimizers with amp.scale_loss(closure_loss, opt) as closure_loss: super().backward(model, closure_loss, optimizer, optimizer_idx, *args, **kwargs)
[docs] def optimizer_step( self, model: Optional[Union["pl.LightningModule", Module]], optimizer: Optimizer, optimizer_idx: int, closure: Callable[[], Any], **kwargs: Any, ) -> Any: if isinstance(optimizer, LBFGS): raise MisconfigurationException( f"apex AMP and the LBFGS optimizer are not compatible (optimizer {optimizer_idx})." ) closure_result = closure() self._after_closure(model, optimizer, optimizer_idx) skipped_backward = closure_result is None # in manual optimization, the closure does not return a value if not isinstance(model, pl.LightningModule) or not model.automatic_optimization or not skipped_backward: return optimizer.step(**kwargs) return closure_result
[docs] def state_dict(self) -> Dict[str, Any]: return amp.state_dict()
[docs] def load_state_dict(self, state_dict: Dict[str, Any]) -> None: amp.load_state_dict(state_dict)

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