Merge branch 'blender-v3.3-release'

doc/python_api/examples/bpy.props.4.py

@@ -6,6 +6,10 @@ It can be useful to perform an action when a property is changed and can be
 used to update other properties or synchronize with external data.
 
 All properties define update functions except for CollectionProperty.
+
+.. warning::
+   Remember that these callbacks may be executed in threaded context.
+
 """
 
 import bpy

doc/python_api/examples/bpy.props.5.py

@@ -6,6 +6,10 @@ Getter/setter functions can be used for boolean, int, float, string and enum pro
 If these callbacks are defined the property will not be stored in the ID properties
 automatically. Instead, the `get` and `set` functions will be called when the property
 is respectively read or written from the API.
+
+.. warning::
+   Remember that these callbacks may be executed in threaded context.
+
 """
 import bpy
 

doc/python_api/examples/bpy.props.py

@@ -7,6 +7,15 @@ Custom properties can be added to any subclass of an :class:`ID`,
 
 These properties can be animated, accessed by the user interface and python
 like Blender's existing properties.
+
+.. warning::
+
+   Access to these properties might happen in threaded context, on a per-data-block level.
+   This has to be carefully considered when using accessors or update callbacks.
+
+   Typically, these callbacks should not affect any other data that the one owned by their data-block.
+   When accessing external non-Blender data, thread safety mechanisms should be considered.
+
 """
 
 import bpy

source/blender/makesrna/intern/rna_ID.c

@@ -234,6 +234,10 @@ const struct IDFilterEnumPropertyItem rna_enum_id_type_filter_items[] = {
 
 #  include "WM_api.h"
 
+#  ifdef WITH_PYTHON
+#    include "BPY_extern.h"
+#  endif
+
 void rna_ID_override_library_property_operation_refname_get(PointerRNA *ptr, char *value)
 {
   IDOverrideLibraryPropertyOperation *opop = ptr->data;
@@ -695,7 +699,16 @@ static ID *rna_ID_override_create(ID *id, Main *bmain, bool remap_local_usages)
     BKE_main_id_tag_all(bmain, LIB_TAG_DOIT, true);
   }
 
-  ID *local_id = BKE_lib_override_library_create_from_id(bmain, id, remap_local_usages);
+  ID *local_id = NULL;
+#  ifdef WITH_PYTHON
+  BPy_BEGIN_ALLOW_THREADS;
+#  endif
+
+  local_id = BKE_lib_override_library_create_from_id(bmain, id, remap_local_usages);
+
+#  ifdef WITH_PYTHON
+  BPy_END_ALLOW_THREADS;
+#  endif
 
   if (remap_local_usages) {
     BKE_main_id_tag_all(bmain, LIB_TAG_DOIT, false);
@@ -717,9 +730,18 @@ static ID *rna_ID_override_hierarchy_create(
   BKE_main_id_tag_all(bmain, LIB_TAG_DOIT, false);
 
   ID *id_root_override = NULL;
+
+#  ifdef WITH_PYTHON
+  BPy_BEGIN_ALLOW_THREADS;
+#  endif
+
   BKE_lib_override_library_create(
       bmain, scene, view_layer, NULL, id, id, id_instance_hint, &id_root_override, false);
 
+#  ifdef WITH_PYTHON
+  BPy_END_ALLOW_THREADS;
+#  endif
+
   WM_main_add_notifier(NC_ID | NA_ADDED, NULL);
   WM_main_add_notifier(NC_WM | ND_LIB_OVERRIDE_CHANGED, NULL);