CheckpointHook¶

class mmengine.hooks.CheckpointHook(interval=- 1, by_epoch=True, save_optimizer=True, save_param_scheduler=True, out_dir=None, max_keep_ckpts=- 1, save_last=True, save_best=None, rule=None, greater_keys=None, less_keys=None, file_client_args=None, filename_tmpl=None, backend_args=None, **kwargs)[source]¶

Save checkpoints periodically.

Parameters

interval (int) – The saving period. If by_epoch=True, interval indicates epochs, otherwise it indicates iterations. Defaults to -1, which means “never”.
by_epoch (bool) – Saving checkpoints by epoch or by iteration. Defaults to True.
save_optimizer (bool) – Whether to save optimizer state_dict in the checkpoint. It is usually used for resuming experiments. Defaults to True.
save_param_scheduler (bool) – Whether to save param_scheduler state_dict in the checkpoint. It is usually used for resuming experiments. Defaults to True.
out_dir (str, Path, Optional) – The root directory to save checkpoints. If not specified, runner.work_dir will be used by default. If specified, the out_dir will be the concatenation of out_dir and the last level directory of runner.work_dir. For example, if the input our_dir is ./tmp and runner.work_dir is ./work_dir/cur_exp, then the ckpt will be saved in ./tmp/cur_exp. Defaults to None.
max_keep_ckpts (int) – The maximum checkpoints to keep. In some cases we want only the latest few checkpoints and would like to delete old ones to save the disk space. Defaults to -1, which means unlimited.
save_last (bool) – Whether to force the last checkpoint to be saved regardless of interval. Defaults to True.
save_best (str, List[str], optional) – If a metric is specified, it would measure the best checkpoint during evaluation. If a list of metrics is passed, it would measure a group of best checkpoints corresponding to the passed metrics. The information about best checkpoint(s) would be saved in runner.message_hub to keep best score value and best checkpoint path, which will be also loaded when resuming checkpoint. Options are the evaluation metrics on the test dataset. e.g., bbox_mAP, segm_mAP for bbox detection and instance segmentation. AR@100 for proposal recall. If save_best is auto, the first key of the returned OrderedDict result will be used. Defaults to None.
rule (str, List[str], optional) – Comparison rule for best score. If set to None, it will infer a reasonable rule. Keys such as ‘acc’, ‘top’ .etc will be inferred by ‘greater’ rule. Keys contain ‘loss’ will be inferred by ‘less’ rule. If save_best is a list of metrics and rule is a str, all metrics in save_best will share the comparison rule. If save_best and rule are both lists, their length must be the same, and metrics in save_best will use the corresponding comparison rule in rule. Options are ‘greater’, ‘less’, None and list which contains ‘greater’ and ‘less’. Defaults to None.
greater_keys (List[str], optional) – Metric keys that will be inferred by ‘greater’ comparison rule. If None, _default_greater_keys will be used. Defaults to None.
less_keys (List[str], optional) – Metric keys that will be inferred by ‘less’ comparison rule. If None, _default_less_keys will be used. Defaults to None.
file_client_args (dict, optional) – Arguments to instantiate a FileClient. See mmengine.fileio.FileClient for details. Defaults to None. It will be deprecated in future. Please use backend_args instead.
filename_tmpl (str, optional) – String template to indicate checkpoint name. If specified, must contain one and only one “{}”, which will be replaced with epoch + 1 if by_epoch=True else iteration + 1. Defaults to None, which means “epoch_{}.pth” or “iter_{}.pth” accordingly.
backend_args (dict, optional) – Arguments to instantiate the preifx of uri corresponding backend. Defaults to None. New in v0.2.0.

Return type

None

Examples

>>> # Save best based on single metric
>>> CheckpointHook(interval=2, by_epoch=True, save_best='acc',
>>>                rule='less')
>>> # Save best based on multi metrics with the same comparison rule
>>> CheckpointHook(interval=2, by_epoch=True,
>>>                save_best=['acc', 'mIoU'], rule='greater')
>>> # Save best based on multi metrics with different comparison rule
>>> CheckpointHook(interval=2, by_epoch=True,
>>>                save_best=['FID', 'IS'], rule=['less', 'greater'])

after_train_epoch(runner)[source]¶

Save the checkpoint and synchronize buffers after each epoch.

Parameters: runner (Runner) – The runner of the training process.
Return type: None

after_train_iter(runner, batch_idx, data_batch=None, outputs=typing.Union[dict, NoneType])[source]¶

Save the checkpoint and synchronize buffers after each iteration.

Parameters

runner (Runner) – The runner of the training process.
batch_idx (int) – The index of the current batch in the train loop.
data_batch (dict or tuple or list, optional) – Data from dataloader.
outputs (dict, optional) – Outputs from model.

Return type

None

after_val_epoch(runner, metrics)[source]¶

Save the checkpoint and synchronize buffers after each evaluation epoch.

Parameters

runner (Runner) – The runner of the training process.
metrics (dict) – Evaluation results of all metrics

before_train(runner)[source]¶

Finish all operations, related to checkpoint.

This function will get the appropriate file client, and the directory to save these checkpoints of the model.

Parameters: runner (Runner) – The runner of the training process.
Return type: None