[Enhance] Support skipping initialization in BaseModule (#1263)

mmengine/model/base_module.py

@@ -59,6 +59,10 @@ def __init__(self, init_cfg: Union[dict, List[dict], None] = None):
     def is_init(self):
         return self._is_init
 
+    @is_init.setter
+    def is_init(self, value):
+        self._is_init = value
+
     def init_weights(self):
         """Initialize the weights."""
 
@@ -127,7 +131,8 @@ def init_weights(self):
             for m in self.children():
                 if is_model_wrapper(m) and not hasattr(m, 'init_weights'):
                     m = m.module
-                if hasattr(m, 'init_weights'):
+                if hasattr(m, 'init_weights') and not getattr(
+                        m, 'is_init', False):
                     m.init_weights()
                     # users may overload the `init_weights`
                     update_init_info(

tests/test_model/test_base_module.py

@@ -4,7 +4,7 @@
 import os.path as osp
 import tempfile
 from unittest import TestCase
-from unittest.mock import patch
+from unittest.mock import Mock, patch
 
 import torch
 from torch import nn
@@ -238,6 +238,30 @@ def __init__(self, module) -> None:
             self.assertTrue((model.ddp.module.linear.weight == 1).all())
             self.assertTrue((model.ddp.module.linear.bias == 2).all())
 
+        # Test submodule.init_weights will be skipped if `is_init` is set
+        # to True in root model
+        model: FooModel = FOOMODELS.build(copy.deepcopy(self.model_cfg))
+        for child in model.children():
+            child.init_weights = Mock()
+        model.is_init = True
+        model.init_weights()
+        for child in model.children():
+            child.init_weights.assert_not_called()
+
+        # Test submodule.init_weights will be skipped if submodule's `is_init`
+        # is set to True
+        model: FooModel = FOOMODELS.build(copy.deepcopy(self.model_cfg))
+        for child in model.children():
+            child.init_weights = Mock()
+        model.component1.is_init = True
+        model.reg.is_init = True
+        model.init_weights()
+        model.component1.init_weights.assert_not_called()
+        model.component2.init_weights.assert_called_once()
+        model.component3.init_weights.assert_called_once()
+        model.component4.init_weights.assert_called_once()
+        model.reg.init_weights.assert_not_called()
+
     def test_dump_init_info(self):
         import os
         import shutil