97 lines
3.1 KiB
ReStructuredText
97 lines
3.1 KiB
ReStructuredText
:orphan:
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.. _checkpointing_expert:
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######################
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Checkpointing (expert)
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######################
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*********************************
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Writing your own Checkpoint class
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*********************************
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We provide ``Checkpoint`` class, for easier subclassing. Users may want to subclass this class in case of writing custom ``ModelCheckpoint`` callback, so that the ``Trainer`` recognizes the custom class as a checkpointing callback.
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***********************
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Customize Checkpointing
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***********************
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.. warning::
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The Checkpoint IO API is experimental and subject to change.
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Lightning supports modifying the checkpointing save/load functionality through the ``CheckpointIO``. This encapsulates the save/load logic
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that is managed by the ``Strategy``. ``CheckpointIO`` is different from :meth:`~pytorch_lightning.core.hooks.CheckpointHooks.on_save_checkpoint`
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and :meth:`~pytorch_lightning.core.hooks.CheckpointHooks.on_load_checkpoint` methods as it determines how the checkpoint is saved/loaded to storage rather than
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what's saved in the checkpoint.
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TODO: I don't understand this...
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******************************
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Built-in Checkpoint IO Plugins
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******************************
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.. list-table:: Built-in Checkpoint IO Plugins
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:widths: 25 75
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:header-rows: 1
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* - Plugin
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- Description
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* - :class:`~pytorch_lightning.plugins.io.TorchCheckpointIO`
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- CheckpointIO that utilizes :func:`torch.save` and :func:`torch.load` to save and load checkpoints
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respectively, common for most use cases.
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* - :class:`~pytorch_lightning.plugins.io.XLACheckpointIO`
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- CheckpointIO that utilizes :func:`xm.save` to save checkpoints for TPU training strategies.
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***************************
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Custom Checkpoint IO Plugin
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***************************
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``CheckpointIO`` can be extended to include your custom save/load functionality to and from a path. The ``CheckpointIO`` object can be passed to either a ``Trainer`` directly or a ``Strategy`` as shown below:
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.. code-block:: python
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from pytorch_lightning import Trainer
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from pytorch_lightning.callbacks import ModelCheckpoint
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from pytorch_lightning.plugins import CheckpointIO
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from pytorch_lightning.strategies import SingleDeviceStrategy
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class CustomCheckpointIO(CheckpointIO):
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def save_checkpoint(self, checkpoint, path, storage_options=None):
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...
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def load_checkpoint(self, path, storage_options=None):
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...
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def remove_checkpoint(self, path):
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...
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custom_checkpoint_io = CustomCheckpointIO()
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# Either pass into the Trainer object
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model = MyModel()
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trainer = Trainer(
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plugins=[custom_checkpoint_io],
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callbacks=ModelCheckpoint(save_last=True),
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)
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trainer.fit(model)
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# or pass into Strategy
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model = MyModel()
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device = torch.device("cpu")
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trainer = Trainer(
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strategy=SingleDeviceStrategy(device, checkpoint_io=custom_checkpoint_io),
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callbacks=ModelCheckpoint(save_last=True),
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)
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trainer.fit(model)
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.. note::
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Some ``TrainingTypePlugins`` like ``DeepSpeedStrategy`` do not support custom ``CheckpointIO`` as checkpointing logic is not modifiable.
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