| # 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 | |
| # | |
| # 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. | |
| # See the License for the specific language governing permissions and | |
| # limitations under the License. | |
| from collections.abc import Iterable, MutableMapping | |
| from torch import Tensor | |
| from torch.optim import Optimizer | |
| from lightning.fabric.utilities.apply_func import apply_to_collection, move_data_to_device | |
| from lightning.fabric.utilities.types import _DEVICE | |
| def _optimizers_to_device(optimizers: Iterable[Optimizer], device: _DEVICE) -> None: | |
| """Moves optimizer states for a sequence of optimizers to the device.""" | |
| for opt in optimizers: | |
| _optimizer_to_device(opt, device) | |
| def _optimizer_to_device(optimizer: Optimizer, device: _DEVICE) -> None: | |
| """Moves the state of a single optimizer to the device.""" | |
| for p, v in optimizer.state.items(): | |
| if not isinstance(v, MutableMapping): | |
| # Support for custom optimizers | |
| optimizer.state[p] = apply_to_collection(v, Tensor, move_data_to_device, device, allow_frozen=True) | |
| continue | |
| for key, val in v.items(): | |
| # The 'step' parameter needs to remain unmoved (possibly on the CPU) since that is where the optimizer | |
| # needs it. See https://github.com/pytorch/pytorch/issues/74424 | |
| if key != "step": | |
| v[key] = move_data_to_device(val, device) | |