import collections.abc as collections
import numbers
import os
import tempfile
import warnings
from abc import ABCMeta, abstractmethod
from collections import OrderedDict
from tempfile import _TemporaryFileWrapper # type: ignore[attr-defined]
from typing import Any, Callable, Dict, List, Mapping, NamedTuple, Optional, Tuple, Union
import torch
import torch.nn as nn
import ignite.distributed as idist
from ignite.base import Serializable
from ignite.engine import Engine, Events
__all__ = ["Checkpoint", "DiskSaver", "ModelCheckpoint", "BaseSaveHandler"]
[docs]class BaseSaveHandler(metaclass=ABCMeta):
"""Base class for save handlers
Methods to override:
- :meth:`~ignite.handlers.checkpoint.BaseSaveHandler.__call__`
- :meth:`~ignite.handlers.checkpoint.BaseSaveHandler.remove`
Note:
In derived class, please, make sure that in distributed configuration overridden methods are called by a single
process. Distributed configuration on XLA devices should be treated slightly differently: for saving checkpoint
with `xm.save() <https://pytorch.org/xla/release/1.5/index.html#torch_xla.core.xla_model.save>`_ all processes
should pass into the function. Otherwise, application gets stuck.
"""
[docs] @abstractmethod
def __call__(self, checkpoint: Mapping, filename: str, metadata: Optional[Mapping] = None) -> None:
"""Method to save `checkpoint` with `filename`. Additionally, metadata dictionary is provided.
Metadata contains:
- `basename`: file prefix (if provided) with checkpoint name, e.g. `epoch_checkpoint`.
- `score_name`: score name if provided, e.g `val_acc`.
- `priority`: checkpoint priority value (higher is better), e.g. `12` or `0.6554435`
Args:
checkpoint (Mapping): checkpoint dictionary to save.
filename (str): filename associated with checkpoint.
metadata (Mapping, optional): metadata on checkpoint to save.
"""
pass
[docs] @abstractmethod
def remove(self, filename: str) -> None:
"""Method to remove saved checkpoint.
Args:
filename (str): filename associated with checkpoint.
"""
pass
[docs]class Checkpoint(Serializable):
"""Checkpoint handler can be used to periodically save and load objects which have attribute
``state_dict/load_state_dict``. This class can use specific save handlers to store on the disk or a cloud
storage, etc. The Checkpoint handler (if used with :class:`~ignite.handlers.DiskSaver`) also handles automatically
moving data on TPU to CPU before writing the checkpoint.
Args:
to_save (Mapping): Dictionary with the objects to save. Objects should have implemented ``state_dict`` and
``load_state_dict`` methods. If contains objects of type torch `DistributedDataParallel`_ or
`DataParallel`_, their internal wrapped model is automatically saved (to avoid additional key ``module.`` in
the state dictionary).
save_handler (callable or :class:`~ignite.handlers.checkpoint.BaseSaveHandler`): Method or callable class to
use to save engine and other provided objects. Function receives two objects: checkpoint as a dictionary
and filename. If ``save_handler`` is callable class, it can
inherit of :class:`~ignite.handlers.checkpoint.BaseSaveHandler` and optionally implement ``remove`` method
to keep a fixed number of saved checkpoints. In case if user needs to save engine's checkpoint on a disk,
``save_handler`` can be defined with :class:`~ignite.handlers.DiskSaver`.
filename_prefix (str, optional): Prefix for the file name to which objects will be saved. See Note for details.
score_function (callable, optional): If not None, it should be a function taking a single argument,
:class:`~ignite.engine.engine.Engine` object, and returning a score (`float`). Objects with highest scores
will be retained.
score_name (str, optional): If ``score_function`` not None, it is possible to store its value using
``score_name``. See Notes for more details.
n_saved (int, optional): Number of objects that should be kept on disk. Older files will be removed. If set to
`None`, all objects are kept.
global_step_transform (callable, optional): global step transform function to output a desired global step.
Input of the function is ``(engine, event_name)``. Output of function should be an integer.
Default is None, global_step based on attached engine. If provided, uses function output as global_step.
To setup global step from another engine, please use :meth:`~ignite.handlers.global_step_from_engine`.
archived (bool, optional): Deprecated argument as models saved by ``torch.save`` are already compressed.
filename_pattern (str, optional): If ``filename_pattern`` is provided, this pattern will be used to render
checkpoint filenames. If the pattern is not defined, the default pattern would be used. See Note for
details.
include_self (bool): Whether to include the `state_dict` of this object in the checkpoint. If `True`, then
there must not be another object in ``to_save`` with key ``checkpointer``.
greater_or_equal (bool): if `True`, the latest equally scored model is stored. Otherwise, the first model.
Default, `False`.
.. _DistributedDataParallel: https://pytorch.org/docs/stable/generated/
torch.nn.parallel.DistributedDataParallel.html
.. _DataParallel: https://pytorch.org/docs/stable/generated/torch.nn.DataParallel.html
Note:
This class stores a single file as a dictionary of provided objects to save.
The filename is defined by ``filename_pattern`` and by default has the following
structure: ``{filename_prefix}_{name}_{suffix}.{ext}`` where
- ``filename_prefix`` is the argument passed to the constructor,
- `name` is the key in ``to_save`` if a single object is to store, otherwise `name` is "checkpoint".
- `suffix` is composed as following ``{global_step}_{score_name}={score}``.
+----------------+------------+-----------------------+----------------------------------------------+
| score_function | score_name | global_step_transform | suffix |
+================+============+=======================+==============================================+
| None | None | None | ``{engine.state.iteration}`` |
+----------------+------------+-----------------------+----------------------------------------------+
| X | None | None | ``{score}`` |
+----------------+------------+-----------------------+----------------------------------------------+
| X | None | X | ``{global_step}_{score}`` |
+----------------+------------+-----------------------+----------------------------------------------+
| X | X | X | ``{global_step}_{score_name}={score}`` |
+----------------+------------+-----------------------+----------------------------------------------+
| None | None | X | ``{global_step}`` |
+----------------+------------+-----------------------+----------------------------------------------+
| X | X | None | ``{score_name}={score}`` |
+----------------+------------+-----------------------+----------------------------------------------+
Above `global_step` defined by the output of `global_step_transform` and `score` defined by the output
of `score_function`.
By default, none of ``score_function``, ``score_name``, ``global_step_transform`` is defined, then suffix is
setup by attached engine's current iteration. The filename will be
`{filename_prefix}_{name}_{engine.state.iteration}.{ext}`.
For example, ``score_name="neg_val_loss"`` and ``score_function`` that returns `-loss` (as objects with highest
scores will be retained), then saved filename will be ``{filename_prefix}_{name}_neg_val_loss=-0.1234.pt``.
Note:
If ``filename_pattern`` is given, it will be used to render the filenames. ``filename_pattern`` is a string
that can contain ``{filename_prefix}``, ``{name}``, ``{score}``, ``{score_name}`` and ``{global_step}`` as
templates.
For example, let ``filename_pattern="{global_step}-{name}-{score}.pt"`` then the saved filename will be
``30000-checkpoint-94.pt``
**Warning:** Please, keep in mind that if filename collide with already used one to saved a checkpoint,
new checkpoint will replace the older one. This means that filename like ``checkpoint.pt`` will be saved
every call and will always be overwritten by newer checkpoints.
Note:
To get the last stored filename, handler exposes attribute ``last_checkpoint``:
.. code-block:: python
handler = Checkpoint(...)
...
print(handler.last_checkpoint)
> checkpoint_12345.pt
Note:
This class is distributed configuration-friendly: it is not required to instantiate the class in rank 0 only
process. This class supports automatically distributed configuration and if used with
:class:`~ignite.handlers.DiskSaver`, checkpoint is stored by rank 0 process.
.. warning::
When running on XLA devices, it should be run in all processes, otherwise application can get stuck on
saving the checkpoint.
.. code-block:: python
# Wrong:
# if idist.get_rank() == 0:
# handler = Checkpoint(...)
# trainer.add_event_handler(Events.ITERATION_COMPLETED(every=1000), handler)
# Correct:
handler = Checkpoint(...)
trainer.add_event_handler(Events.ITERATION_COMPLETED(every=1000), handler)
Examples:
Attach the handler to make checkpoints during training:
.. code-block:: python
from ignite.engine import Engine, Events
from ignite.handlers import Checkpoint, DiskSaver
trainer = ...
model = ...
optimizer = ...
lr_scheduler = ...
to_save = {'model': model, 'optimizer': optimizer, 'lr_scheduler': lr_scheduler, 'trainer': trainer}
if (checkpoint_iters):
# A: Output is "checkpoint_<iteration>.pt"
handler = Checkpoint(
to_save, DiskSaver('/tmp/models', create_dir=True), n_saved=2
)
trainer.add_event_handler(Events.ITERATION_COMPLETED(every=1000), handler)
else:
# B:Output is "checkpoint_<epoch>.pt"
gst = lambda *_: trainer.state.epoch
handler = Checkpoint(
to_save, DiskSaver('/tmp/models', create_dir=True), n_saved=2, global_step_transform=gst
)
trainer.add_event_handler(Events.EPOCH_COMPLETED, handler)
trainer.run(data_loader, max_epochs=6)
> A: ["checkpoint_7000.pt", "checkpoint_8000.pt", ]
> B: ["checkpoint_5.pt", "checkpoint_6.pt", ]
Attach the handler to an evaluator to save best model during the training
according to computed validation metric:
.. code-block:: python
from ignite.engine import Engine, Events
from ignite.handlers import Checkpoint, DiskSaver, global_step_from_engine
trainer = ...
evaluator = ...
# Setup Accuracy metric computation on evaluator
# Run evaluation on epoch completed event
# ...
score_function = Checkpoint.get_default_score_fn("accuracy")
to_save = {'model': model}
handler = Checkpoint(
to_save, DiskSaver('/tmp/models', create_dir=True),
n_saved=2, filename_prefix='best',
score_function=score_function, score_name="val_acc",
global_step_transform=global_step_from_engine(trainer)
)
evaluator.add_event_handler(Events.COMPLETED, handler)
trainer.run(data_loader, max_epochs=10)
> ["best_model_9_val_acc=0.77.pt", "best_model_10_val_acc=0.78.pt", ]
.. versionchanged:: 0.4.3
- Checkpoint can save model with same filename.
- Added ``greater_or_equal`` argument.
"""
Item = NamedTuple("Item", [("priority", int), ("filename", str)])
_state_dict_all_req_keys = ("saved",)
def __init__(
self,
to_save: Mapping,
save_handler: Union[Callable, BaseSaveHandler],
filename_prefix: str = "",
score_function: Optional[Callable] = None,
score_name: Optional[str] = None,
n_saved: Optional[int] = 1,
global_step_transform: Optional[Callable] = None,
archived: bool = False,
filename_pattern: Optional[str] = None,
include_self: bool = False,
greater_or_equal: bool = False,
) -> None:
if not isinstance(to_save, collections.Mapping):
raise TypeError(f"Argument `to_save` should be a dictionary, but given {type(to_save)}")
self._check_objects(to_save, "state_dict")
if include_self:
if not isinstance(to_save, collections.MutableMapping):
raise TypeError(
f"If `include_self` is True, then `to_save` must be mutable, but given {type(to_save)}."
)
if "checkpointer" in to_save:
raise ValueError(f"Cannot have key 'checkpointer' if `include_self` is True: {to_save}")
if not (callable(save_handler) or isinstance(save_handler, BaseSaveHandler)):
raise TypeError("Argument `save_handler` should be callable or inherit from BaseSaveHandler")
if score_function is None and score_name is not None:
raise ValueError("If `score_name` is provided, then `score_function` " "should be also provided.")
if global_step_transform is not None and not callable(global_step_transform):
raise TypeError(f"global_step_transform should be a function, got {type(global_step_transform)} instead.")
if archived:
warnings.warn("Argument archived is deprecated and will be removed in 0.5.0")
self.to_save = to_save
self.filename_prefix = filename_prefix
self.save_handler = save_handler
self.score_function = score_function
self.score_name = score_name
self.n_saved = n_saved
self.ext = "pt"
self.global_step_transform = global_step_transform
self.filename_pattern = filename_pattern
self._saved = [] # type: List["Checkpoint.Item"]
self.include_self = include_self
self.greater_or_equal = greater_or_equal
[docs] def reset(self) -> None:
"""Method to reset saved checkpoint names.
Use this method if the engine will independently run multiple times:
.. code-block:: python
from ignite.handlers import Checkpoint
trainer = ...
checkpointer = Checkpoint(...)
trainer.add_event_handler(Events.COMPLETED, checkpointer)
trainer.add_event_handler(Events.STARTED, checkpointer.reset)
# fold 0
trainer.run(data0, max_epochs=max_epochs)
print("Last checkpoint:", checkpointer.last_checkpoint)
# fold 1
trainer.run(data1, max_epochs=max_epochs)
print("Last checkpoint:", checkpointer.last_checkpoint)
.. versionadded:: 0.4.3
"""
self._saved = []
@property
def last_checkpoint(self) -> Optional[str]:
if len(self._saved) < 1:
return None
return self._saved[-1].filename
def _check_lt_n_saved(self, or_equal: bool = False) -> bool:
if self.n_saved is None:
return True
return len(self._saved) < self.n_saved + int(or_equal)
def _compare_fn(self, new: Union[int, float]) -> bool:
if self.greater_or_equal:
return new >= self._saved[0].priority
else:
return new > self._saved[0].priority
def __call__(self, engine: Engine) -> None:
global_step = None
if self.global_step_transform is not None:
global_step = self.global_step_transform(engine, engine.last_event_name)
if self.score_function is not None:
priority = self.score_function(engine)
if not isinstance(priority, numbers.Number):
raise ValueError("Output of score_function should be a number")
else:
if global_step is None:
global_step = engine.state.get_event_attrib_value(Events.ITERATION_COMPLETED)
priority = global_step
if self._check_lt_n_saved() or self._compare_fn(priority):
priority_str = f"{priority}" if isinstance(priority, numbers.Integral) else f"{priority:.4f}"
checkpoint = self._setup_checkpoint()
name = "checkpoint"
if len(checkpoint) == 1:
for k in checkpoint:
name = k
checkpoint = checkpoint[name]
if self.filename_pattern is None:
filename_pattern = self.setup_filename_pattern(
with_prefix=len(self.filename_prefix) > 0,
with_score=self.score_function is not None,
with_score_name=self.score_name is not None,
with_global_step=global_step is not None,
)
else:
filename_pattern = self.filename_pattern
filename_dict = {
"filename_prefix": self.filename_prefix,
"ext": self.ext,
"name": name,
"score_name": self.score_name,
"score": priority_str if (self.score_function is not None) else None,
"global_step": global_step,
}
filename = filename_pattern.format(**filename_dict)
metadata = {
"basename": f"{self.filename_prefix}{'_' * int(len(self.filename_prefix) > 0)}{name}",
"score_name": self.score_name,
"priority": priority,
}
try:
index = list(map(lambda it: it.filename == filename, self._saved)).index(True)
to_remove = True
except ValueError:
index = 0
to_remove = not self._check_lt_n_saved()
if to_remove:
item = self._saved.pop(index)
if isinstance(self.save_handler, BaseSaveHandler):
self.save_handler.remove(item.filename)
self._saved.append(Checkpoint.Item(priority, filename))
self._saved.sort(key=lambda it: it[0])
if self.include_self:
# Now that we've updated _saved, we can add our own state_dict.
checkpoint["checkpointer"] = self.state_dict()
try:
self.save_handler(checkpoint, filename, metadata)
except TypeError:
self.save_handler(checkpoint, filename)
def _setup_checkpoint(self) -> Dict[str, Dict[Any, Any]]:
checkpoint = {}
if self.to_save is not None:
for k, obj in self.to_save.items():
if isinstance(obj, (nn.DataParallel, nn.parallel.DistributedDataParallel)):
obj = obj.module
checkpoint[k] = obj.state_dict()
return checkpoint
[docs] @staticmethod
def setup_filename_pattern(
with_prefix: bool = True, with_score: bool = True, with_score_name: bool = True, with_global_step: bool = True,
) -> str:
"""Helper method to get the default filename pattern for a checkpoint.
Args:
with_prefix (bool): If True, the ``filename_prefix`` is added to the filename pattern:
``{filename_prefix}_{name}...``. Default, True.
with_score (bool): If True, ``score`` is added to the filename pattern: ``..._{score}.{ext}``.
Default, True. At least one of ``with_score`` and ``with_global_step`` should be True.
with_score_name (bool): If True, ``score_name`` is added to the filename pattern:
``..._{score_name}={score}.{ext}``. If activated, argument ``with_score`` should be
also True, otherwise an error is raised. Default, True.
with_global_step (bool): If True, ``{global_step}`` is added to the
filename pattern: ``...{name}_{global_step}...``.
At least one of ``with_score`` and ``with_global_step`` should be True.
Example:
.. code-block:: python
from ignite.handlers import Checkpoint
filename_pattern = Checkpoint.setup_filename_pattern()
print(filename_pattern)
> "{filename_prefix}_{name}_{global_step}_{score_name}={score}.{ext}"
.. versionadded:: 0.4.3
"""
filename_pattern = "{name}"
if not (with_global_step or with_score):
raise ValueError("At least one of with_score and with_global_step should be True.")
if with_global_step:
filename_pattern += "_{global_step}"
if with_score_name and with_score:
filename_pattern += "_{score_name}={score}"
elif with_score:
filename_pattern += "_{score}"
elif with_score_name:
raise ValueError("If with_score_name is True, with_score should be also True")
if with_prefix:
filename_pattern = "{filename_prefix}_" + filename_pattern
filename_pattern += ".{ext}"
return filename_pattern
@staticmethod
def _check_objects(objs: Mapping, attr: str) -> None:
for k, obj in objs.items():
if not hasattr(obj, attr):
raise TypeError(f"Object {type(obj)} should have `{attr}` method")
[docs] @staticmethod
def load_objects(to_load: Mapping, checkpoint: Mapping, **kwargs: Any) -> None:
"""Helper method to apply ``load_state_dict`` on the objects from ``to_load`` using states from ``checkpoint``.
Exemples:
.. code-block:: python
import torch
from ignite.engine import Engine, Events
from ignite.handlers import ModelCheckpoint, Checkpoint
trainer = Engine(lambda engine, batch: None)
handler = ModelCheckpoint('/tmp/models', 'myprefix', n_saved=None, create_dir=True)
model = torch.nn.Linear(3, 3)
optimizer = torch.optim.SGD(model.parameters(), lr=1e-3)
to_save = {"weights": model, "optimizer": optimizer}
trainer.add_event_handler(Events.EPOCH_COMPLETED(every=2), handler, to_save)
trainer.run(torch.randn(10, 1), 5)
to_load = to_save
checkpoint_fp = "/tmp/models/myprefix_checkpoint_40.pth"
checkpoint = torch.load(checkpoint_fp)
Checkpoint.load_objects(to_load=to_load, checkpoint=checkpoint)
Note:
If ``to_load`` contains objects of type torch `DistributedDataParallel`_ or
`DataParallel`_, method ``load_state_dict`` will applied to their internal wrapped model (``obj.module``).
Args:
to_load (Mapping): a dictionary with objects, e.g. `{"model": model, "optimizer": optimizer, ...}`
checkpoint (Mapping): a dictionary with state_dicts to load, e.g. `{"model": model_state_dict,
"optimizer": opt_state_dict}`. If `to_load` contains a single key, then checkpoint can contain directly
corresponding state_dict.
**kwargs: Keyword arguments accepted for `nn.Module.load_state_dict()`. Passing `strict=False` enables
the user to load part of the pretrained model (useful for example, in Transfer Learning)
.. _DistributedDataParallel: https://pytorch.org/docs/stable/generated/
torch.nn.parallel.DistributedDataParallel.html
.. _DataParallel: https://pytorch.org/docs/stable/generated/torch.nn.DataParallel.html
"""
Checkpoint._check_objects(to_load, "load_state_dict")
if not isinstance(checkpoint, collections.Mapping):
raise TypeError(f"Argument checkpoint should be a dictionary, but given {type(checkpoint)}")
if len(kwargs) > 1 or any(k for k in kwargs.keys() if k not in ["strict"]):
warnings.warn("kwargs contains keys other than strict and these will be ignored")
is_state_dict_strict = kwargs.get("strict", True)
if len(to_load) == 1:
# single object and checkpoint is directly a state_dict
key, obj = list(to_load.items())[0]
if key not in checkpoint:
if isinstance(obj, (nn.DataParallel, nn.parallel.DistributedDataParallel)):
obj = obj.module
obj.load_state_dict(checkpoint, strict=is_state_dict_strict)
return
# multiple objects to load
for k, obj in to_load.items():
if k not in checkpoint:
raise ValueError(f"Object labeled by '{k}' from `to_load` is not found in the checkpoint")
if isinstance(obj, (nn.DataParallel, nn.parallel.DistributedDataParallel)):
obj = obj.module
if isinstance(obj, torch.nn.Module):
obj.load_state_dict(checkpoint[k], strict=is_state_dict_strict)
else:
obj.load_state_dict(checkpoint[k])
[docs] def state_dict(self) -> "OrderedDict[str, List[Tuple[int, str]]]":
"""Method returns state dict with saved items: list of ``(priority, filename)`` pairs.
Can be used to save internal state of the class.
"""
return OrderedDict([("saved", [(p, f) for p, f in self._saved])])
[docs] def load_state_dict(self, state_dict: Mapping) -> None:
"""Method replace internal state of the class with provided state dict data.
Args:
state_dict (Mapping): a dict with "saved" key and list of ``(priority, filename)`` pairs as values.
"""
super().load_state_dict(state_dict)
self._saved = [Checkpoint.Item(p, f) for p, f in state_dict["saved"]]
[docs] @staticmethod
def get_default_score_fn(metric_name: str, score_sign: float = 1.0) -> Callable:
"""Helper method to get default score function based on the metric name.
Args:
metric_name (str): metric name to get the value from ``engine.state.metrics``.
Engine is the one to which :class:`~ignite.handlers.checkpoint.Checkpoint` handler is added.
score_sign (float): sign of the score: 1.0 or -1.0. For error-like metrics, e.g. smaller is better,
a negative score sign should be used (objects with larger score are retained). Default, 1.0.
Exemples:
.. code-block:: python
from ignite.handlers import Checkpoint
best_acc_score = Checkpoint.get_default_score_fn("accuracy")
best_model_handler = Checkpoint(
to_save, save_handler, score_name="val_accuracy", score_function=best_acc_score
)
evaluator.add_event_handler(Events.COMPLETED, best_model_handler)
Usage with error-like metric:
.. code-block:: python
from ignite.handlers import Checkpoint
neg_loss_score = Checkpoint.get_default_score_fn("loss", -1.0)
best_model_handler = Checkpoint(
to_save, save_handler, score_name="val_neg_loss", score_function=neg_loss_score
)
evaluator.add_event_handler(Events.COMPLETED, best_model_handler)
.. versionadded:: 0.4.3
"""
if score_sign not in (1.0, -1.0):
raise ValueError("Argument score_sign should be 1 or -1")
def wrapper(engine: Engine) -> float:
return score_sign * engine.state.metrics[metric_name]
return wrapper
[docs]class DiskSaver(BaseSaveHandler):
"""Handler that saves input checkpoint on a disk.
Args:
dirname (str): Directory path where the checkpoint will be saved
atomic (bool, optional): if True, checkpoint is serialized to a temporary file, and then
moved to final destination, so that files are guaranteed to not be damaged
(for example if exception occurs during saving).
create_dir (bool, optional): if True, will create directory ``dirname`` if it doesnt exist.
require_empty (bool, optional): If True, will raise exception if there are any files in the
directory ``dirname``.
**kwargs: Accepted keyword arguments for `torch.save` or `xm.save`.
.. versionchanged:: 0.4.2
Accept ``kwargs`` for `torch.save` or `xm.save`.
"""
def __init__(
self, dirname: str, atomic: bool = True, create_dir: bool = True, require_empty: bool = True, **kwargs: Any
) -> None:
self.dirname = os.path.expanduser(dirname)
self._atomic = atomic
self._check_and_setup(dirname, create_dir, require_empty)
self.kwargs = kwargs
@staticmethod
@idist.one_rank_only()
def _check_and_setup(dirname: str, create_dir: bool, require_empty: bool) -> None:
if create_dir:
if not os.path.exists(dirname):
os.makedirs(dirname)
# Ensure that dirname exists
if not os.path.exists(dirname):
raise ValueError(f"Directory path '{dirname}' is not found")
if require_empty:
matched = [fname for fname in os.listdir(dirname) if fname.endswith(".pt")]
if len(matched) > 0:
raise ValueError(
f"Files {matched} with extension '.pt' are already present "
f"in the directory {dirname}. If you want to use this "
"directory anyway, pass `require_empty=False`."
""
)
def __call__(self, checkpoint: Mapping, filename: str, metadata: Optional[Mapping] = None) -> None:
path = os.path.join(self.dirname, filename)
if idist.has_xla_support:
self._save_xla(checkpoint, path)
else:
self._save_native(checkpoint, path)
@idist.one_rank_only()
def _save_native(self, checkpoint: Mapping, path: str) -> None:
self._save_func(checkpoint, path, torch.save)
def _save_xla(self, checkpoint: Mapping, path: str) -> None:
import torch_xla.core.xla_model as xm
# all tpu procs should enter here as internally performs sync across device
self._save_func(checkpoint, path, xm.save, rank=idist.get_rank())
def _save_func(self, checkpoint: Mapping, path: str, func: Callable, rank: int = 0) -> None:
if not self._atomic:
func(checkpoint, path, **self.kwargs)
else:
tmp_file = None
tmp_name = ""
tmp = None # type: _TemporaryFileWrapper
if rank == 0:
tmp = tempfile.NamedTemporaryFile(delete=False, dir=self.dirname)
tmp_file = tmp.file
tmp_name = tmp.name
try:
func(checkpoint, tmp_file, **self.kwargs)
except BaseException:
if tmp is not None:
tmp.close()
os.remove(tmp_name)
raise
else:
if tmp is not None:
tmp.close()
os.rename(tmp.name, path)
@idist.one_rank_only()
def remove(self, filename: str) -> None:
path = os.path.join(self.dirname, filename)
os.remove(path)
[docs]class ModelCheckpoint(Checkpoint):
"""ModelCheckpoint handler can be used to periodically save objects to disk only. If needed to store checkpoints to
another storage type, please consider :class:`~ignite.handlers.checkpoint.Checkpoint`.
This handler expects two arguments:
- an :class:`~ignite.engine.engine.Engine` object
- a `dict` mapping names (`str`) to objects that should be saved to disk.
See Examples for further details.
.. warning::
Behaviour of this class has been changed since v0.3.0.
Argument ``save_as_state_dict`` is deprecated and should not be used. It is considered as True.
Argument ``save_interval`` is deprecated and should not be used. Please, use events filtering instead, e.g.
:attr:`~ignite.engine.events.Events.ITERATION_STARTED(every=1000)`
There is no more internal counter that has been used to indicate the number of save actions. User could
see its value `step_number` in the filename, e.g. `{filename_prefix}_{name}_{step_number}.pt`. Actually,
`step_number` is replaced by current engine's epoch if `score_function` is specified and current iteration
otherwise.
A single `pt` file is created instead of multiple files.
Args:
dirname (str): Directory path where objects will be saved.
filename_prefix (str): Prefix for the file names to which objects will be saved. See Notes of
:class:`~ignite.handlers.Checkpoint` for more details.
score_function (callable, optional): if not None, it should be a function taking a single argument, an
:class:`~ignite.engine.engine.Engine` object, and return a score (`float`). Objects with highest scores
will be retained.
score_name (str, optional): if ``score_function`` not None, it is possible to store its value using
`score_name`. See Notes for more details.
n_saved (int, optional): Number of objects that should be kept on disk. Older files will be removed. If set to
`None`, all objects are kept.
atomic (bool, optional): If True, objects are serialized to a temporary file, and then moved to final
destination, so that files are guaranteed to not be damaged (for example if exception
occurs during saving).
require_empty (bool, optional): If True, will raise exception if there are any files starting with
``filename_prefix`` in the directory ``dirname``.
create_dir (bool, optional): If True, will create directory ``dirname`` if it does not exist.
global_step_transform (callable, optional): global step transform function to output a desired global step.
Input of the function is `(engine, event_name)`. Output of function should be an integer.
Default is None, global_step based on attached engine. If provided, uses function output as global_step.
To setup global step from another engine, please use :meth:`~ignite.handlers.global_step_from_engine`.
archived (bool, optional): Deprecated argument as models saved by `torch.save` are already compressed.
include_self (bool): Whether to include the `state_dict` of this object in the checkpoint. If `True`, then
there must not be another object in ``to_save`` with key ``checkpointer``.
**kwargs: Accepted keyword arguments for `torch.save` or `xm.save` in `DiskSaver`.
.. versionchanged:: 0.4.2
Accept ``kwargs`` for `torch.save` or `xm.save`
Examples:
>>> import os
>>> from ignite.engine import Engine, Events
>>> from ignite.handlers import ModelCheckpoint
>>> from torch import nn
>>> trainer = Engine(lambda engine, batch: None)
>>> handler = ModelCheckpoint('/tmp/models', 'myprefix', n_saved=2, create_dir=True)
>>> model = nn.Linear(3, 3)
>>> trainer.add_event_handler(Events.EPOCH_COMPLETED(every=2), handler, {'mymodel': model})
>>> trainer.run([0, 1, 2, 3, 4], max_epochs=6)
>>> os.listdir('/tmp/models')
['myprefix_mymodel_20.pt', 'myprefix_mymodel_30.pt']
>>> handler.last_checkpoint
['/tmp/models/myprefix_mymodel_30.pt']
"""
def __init__(
self,
dirname: str,
filename_prefix: str,
save_interval: Optional[int] = None,
score_function: Optional[Callable] = None,
score_name: Optional[str] = None,
n_saved: Union[int, None] = 1,
atomic: bool = True,
require_empty: bool = True,
create_dir: bool = True,
save_as_state_dict: bool = True,
global_step_transform: Optional[Callable] = None,
archived: bool = False,
include_self: bool = False,
**kwargs: Any,
) -> None:
if not save_as_state_dict:
raise ValueError(
"Argument save_as_state_dict is deprecated and should be True."
"This argument will be removed in 0.5.0."
)
if save_interval is not None:
msg = (
"Argument save_interval is deprecated and should be None. This argument will be removed in 0.5.0."
"Please, use events filtering instead, e.g. Events.ITERATION_STARTED(every=1000)"
)
if save_interval == 1:
# Do not break for old version who used `save_interval=1`
warnings.warn(msg)
else:
# No choice
raise ValueError(msg)
disk_saver = DiskSaver(dirname, atomic=atomic, create_dir=create_dir, require_empty=require_empty, **kwargs)
super(ModelCheckpoint, self).__init__(
to_save={},
save_handler=disk_saver,
filename_prefix=filename_prefix,
score_function=score_function,
score_name=score_name,
n_saved=n_saved,
global_step_transform=global_step_transform,
archived=archived,
include_self=include_self,
)
@property
def last_checkpoint(self) -> Union[str, None]:
if len(self._saved) < 1:
return None
if not isinstance(self.save_handler, DiskSaver):
raise RuntimeError(
f"Unable to save checkpoint, save_handler should be DiskSaver, got {type(self.save_handler)}."
)
return os.path.join(self.save_handler.dirname, self._saved[-1].filename)
def __call__(self, engine: Engine, to_save: Mapping) -> None: # type: ignore
if len(to_save) == 0:
raise RuntimeError("No objects to checkpoint found.")
self._check_objects(to_save, "state_dict")
self.to_save = to_save
super(ModelCheckpoint, self).__call__(engine)