[Feature] Publish models after training if published_keys is set in CheckpointHook

docs/en/tutorials/hook.md

@@ -70,6 +70,7 @@ runner.train()
 - Save the most recent checkpoints
 - Save the best checkpoints
 - Specify the path to save the checkpoints
+- Make checkpoints for publish
 
 For more features, please read the [CheckpointHook API documentation](mmengine.hooks.CheckpointHook).
 
@@ -120,6 +121,14 @@ The four features mentioned above are described below.
   default_hooks = dict(checkpoint=dict(type='CheckpointHook', interval=5, out_dir='/path/of/directory'))
   ```
 
+- Make checkpoints for publish
+
+  If you want to automatically generate publishable checkpoints after training (remove unnecessary keys, such as optimizer state), you can set the `published_keys` parameter to choose which information to keep. Note: You need to set the `save_best` or `save_last` parameters accordingly so that the releasable checkpoints will be generated. Setting `save_best` will generate the releasable weights of the optimal checkpoint, and setting `save_last` will generate the releasable final checkpoint. These two parameters can also be set at the same time.
+
+  ```python
+  default_hooks = dict(checkpoint=dict(type='CheckpointHook', interval=1, save_best='accuracy', rule='less', published_keys=['meta', 'state_dict']))
+  ```
+
 [LoggerHook](mmengine.hooks.LoggerHook) collects logs from different components of `Runner` and write them to terminal, JSON file, tensorboard and wandb .etc.
 
 If we want to output (or save) the logs every 20 iterations, we can set the `interval` parameter and configure it as follows.

docs/zh_cn/tutorials/hook.md

@@ -71,6 +71,7 @@ runner.train()
 - 保存最新的多个权重
 - 保存最优权重
 - 指定保存权重的路径
+- 制作发布用的权重
 
 如需了解其他功能，请阅读 [CheckpointHook API 文档](mmengine.hooks.CheckpointHook)。
 
@@ -121,6 +122,14 @@ runner.train()
   default_hooks = dict(checkpoint=dict(type='CheckpointHook', interval=5, out_dir='/path/of/directory'))
   ```
 
+- 制作发布用的权重
+
+  如果你想在训练结束后自动生成可发布的权重（删除不需要的权重，例如优化器状态），你可以设置 `published_keys` 参数，选择需要保留的信息。注意：需要相应设置 `save_best` 或者 `save_last` 参数，这样才会生成可发布的权重，其中设置 `save_best` 会生成最优权重的可发布权重，设置 `save_last` 会生成最后一个权重的可发布权重，这两个参数也可同时设置。
+
+  ```python
+  default_hooks = dict(checkpoint=dict(type='CheckpointHook', interval=1, save_best='accuracy', rule='less', published_keys=['meta', 'state_dict']))
+  ```
+
 ### LoggerHook
 
 [LoggerHook](mmengine.hooks.LoggerHook) 负责收集日志并把日志输出到终端或者输出到文件、TensorBoard 等后端。

mmengine/hooks/checkpoint_hook.py

@@ -1,6 +1,8 @@
 # Copyright (c) OpenMMLab. All rights reserved.
+import hashlib
 import logging
 import os.path as osp
+import pickle
 from math import inf
 from pathlib import Path
 from typing import Callable, Dict, List, Optional, Sequence, Union
@@ -84,7 +86,11 @@ class CheckpointHook(Hook):
         backend_args (dict, optional): Arguments to instantiate the
             prefix of uri corresponding backend. Defaults to None.
             New in v0.2.0.
-
+        published_keys (str, List[str], optional): If ``save_last`` is ``True``
+            or ``save_best`` is not ``None``, it will automatically
+            publish model with keys in the list after training.
+            Defaults to None.
+            `New in version 0.7.1.`
     Examples:
         >>> # Save best based on single metric
         >>> CheckpointHook(interval=2, by_epoch=True, save_best='acc',
@@ -95,6 +101,9 @@ class CheckpointHook(Hook):
         >>> # Save best based on multi metrics with different comparison rule
         >>> CheckpointHook(interval=2, by_epoch=True,
         >>>                save_best=['FID', 'IS'], rule=['less', 'greater'])
+        >>> # Save best based on single metric and publish model after training
+        >>> CheckpointHook(interval=2, by_epoch=True, save_best='acc',
+        >>>                rule='less', published_keys=['meta', 'state_dict'])
     """
     out_dir: str
 
@@ -128,6 +137,7 @@ def __init__(self,
                  file_client_args: Optional[dict] = None,
                  filename_tmpl: Optional[str] = None,
                  backend_args: Optional[dict] = None,
+                 published_keys: Union[str, List[str], None] = None,
                  **kwargs) -> None:
         self.interval = interval
         self.by_epoch = by_epoch
@@ -218,6 +228,20 @@ def __init__(self,
             else:
                 self.best_ckpt_path_dict: Dict = dict()
 
+        # published keys
+        if not (isinstance(published_keys, str)
+                or is_list_of(published_keys, str) or published_keys is None):
+            raise TypeError(
+                '"published_keys" should be a str or list of str or None, '
+                f'but got {type(published_keys)}')
+
+        if isinstance(published_keys, str):
+            published_keys = [published_keys]
+        elif isinstance(published_keys, list):
+            assert len(published_keys) == len(set(published_keys)), (
+                'Find duplicate elements in "published_keys".')
+        self.published_keys = published_keys
+
     def before_train(self, runner) -> None:
         """Finish all operations, related to checkpoint.
 
@@ -304,6 +328,56 @@ def after_val_epoch(self, runner, metrics):
 
         self._save_best_checkpoint(runner, metrics)
 
+    def after_train(self, runner) -> None:
+        """Publish the checkpoint after training.
+
+        Args:
+            runner (Runner): The runner of the training process.
+        """
+        if self.published_keys is None:
+            return
+
+        if self.save_last and 'last_ckpt' in runner.message_hub.runtime_info:
+            last_ckpt = runner.message_hub.get_info('last_ckpt')
+            self._publish_model(runner, last_ckpt)
+
+        if getattr(self, 'best_ckpt_path', None) is not None:
+            self._publish_model(runner, str(self.best_ckpt_path))
+        if getattr(self, 'best_ckpt_path_dict', None) is not None:
+            for key, best_ckpt in self.best_ckpt_path_dict.items():
+                self._publish_model(runner, best_ckpt)
+
+    def _publish_model(self, runner, ckpt_path: str) -> None:
+        """Remove unnecessary keys from ckpt_path and save the new checkpoint.
+
+        Args:
+            runner (Runner): The runner of the training process.
+            ckpt_path (str): The checkpoint path that ought to be published.
+        """
+        from mmengine.runner import save_checkpoint
+        from mmengine.runner.checkpoint import _load_checkpoint
+        checkpoint = _load_checkpoint(ckpt_path)
+        assert self.published_keys is not None
+        removed_keys = []
+        for key in list(checkpoint.keys()):
+            if key not in self.published_keys:
+                removed_keys.append(key)
+                checkpoint.pop(key)
+        if removed_keys:
+            print_log(
+                f'Key {removed_keys} will be removed because they are not '
+                'found in published_keys. If you want to keep them, '
+                f'please set `{removed_keys}` in published_keys',
+                logger='current')
+        checkpoint_data = pickle.dumps(checkpoint)
+        sha = hashlib.sha256(checkpoint_data).hexdigest()
+        final_path = osp.splitext(ckpt_path)[0] + f'-{sha[:8]}.pth'
+        save_checkpoint(checkpoint, final_path)
+        print_log(
+            f'The checkpoint ({ckpt_path}) is published to '
+            f'{final_path}.',
+            logger='current')
+
     def _save_checkpoint(self, runner) -> None:
         """Save the current checkpoint and delete outdated checkpoint.
 

tests/test_hooks/test_checkpoint_hook.py

@@ -465,7 +465,10 @@ def test_with_runner(self, tmp_path):
             type='CheckpointHook',
             interval=save_interval,
             filename_tmpl=tmpl,
-            by_epoch=True)
+            by_epoch=True,
+            save_best='test/acc',
+            rule='less',
+            published_keys=['meta', 'state_dict'])
         runner = Runner(
             model=ToyModel(),
             work_dir=work_dir,