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Maniphest T82149

Blender crash when using collection user_id remapping (python)
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Description

System Information
Operating system: Linux-5.8.16-2-MANJARO-x86_64-with-arch-Manjaro-Linux 64 Bits
Graphics card: GeForce GTX 1660 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 440.100

Blender Version
Broken: version: 2.91.0 Beta, branch: master, commit date: 2020-10-23 17:33, hash: `rB70cc0d7121aa;
Wont work in 2.83 and 2.90 too
Worked: 2.82a
Caused by rB37e08e526c6f: Depsgraph: Add IDProperties handling.

Short description of error
Python script from attached blend file crashes Blender with error:

  • /snap/blender/47/./blender-wrapper: linie 19: 37036 Naruszenie ochrony pamięci (somthing about memory override error) (zrzut pamięci) $SNAP/blender "$@"

What the script does is:

  • add and assign custom PropertyGroup property to bpy.types.Collections
  • create new collection that is used for user remapping of existing collection 'cube_coll'.
  • if we assign some parameter to new PropertyGroup Parameter blender will crash

Script wont crash if we comment out new property assignment, or user remapping.

The script:

import bpy

class CollectionsSettings(bpy.types.PropertyGroup):
    parent: bpy.props.PointerProperty(name="parent", type=bpy.types.Collection)
    
bpy.utils.register_class(CollectionsSettings)

bpy.types.Collection.prop = bpy.props.PointerProperty(type=CollectionsSettings)

# 4 lines below gives crash
cube_col = bpy.data.collections['Cube_coll']
new_col = bpy.data.collections.new('new_col')
new_col.prop.parent = cube_col

cube_col.id_data.user_remap(new_col)

Exact steps for others to reproduce the error
Just execute script from text editor to see the crash.

col_pointer_crash.blend134 KBDownload

Revisions and Commits

rB Blender
D9365rB0d772221c641 Fix T82149: Blender crash when using collection user_id remapping (python).

Related Objects

Event Timeline

Jose Conseco (joseconseco) created this task.Oct 27 2020, 3:56 PM
Philipp Oeser (lichtwerk) changed the task status from Needs Triage to Confirmed.Oct 27 2020, 5:02 PM
Philipp Oeser (lichtwerk) changed the subtype of this task from "Report" to "Bug".
Philipp Oeser (lichtwerk) added projects: Pipeline, Assets & I/O, Python API.
Philipp Oeser (lichtwerk) added a subscriber: Philipp Oeser (lichtwerk).

Can confirm, caused by rB37e08e526c6f: Depsgraph: Add IDProperties handling.

This is only the case if you remap to the same id that holds the property -- and in that case, looks like this enters infinite recursion

1   IDP_foreach_property                                       idprop.c                 1145 0x31b3297 
2   blender::deg::DepsgraphRelationBuilder::build_idproperties deg_builder_relations.cc 578  0xa34c6eb 
3   blender::deg::DepsgraphRelationBuilder::build_collection   deg_builder_relations.cc 594  0xa34c751 
4   blender::deg::DepsgraphRelationBuilder::build_id           deg_builder_relations.cc 497  0xa34c35e 
5   blender::deg::build_idproperties_callback                  deg_builder_relations.cc 573  0xa34c6b9 
6   IDP_foreach_property                                       idprop.c                 1151 0x31b32e6 
7   IDP_foreach_property                                       idprop.c                 1158 0x31b3325 
8   IDP_foreach_property                                       idprop.c                 1158 0x31b3325 
9   blender::deg::DepsgraphRelationBuilder::build_idproperties deg_builder_relations.cc 578  0xa34c6eb 
10  blender::deg::DepsgraphRelationBuilder::build_collection   deg_builder_relations.cc 594  0xa34c751 
11  blender::deg::DepsgraphRelationBuilder::build_id           deg_builder_relations.cc 497  0xa34c35e 
12  blender::deg::build_idproperties_callback                  deg_builder_relations.cc 573  0xa34c6b9 
13  IDP_foreach_property                                       idprop.c                 1151 0x31b32e6 
14  IDP_foreach_property                                       idprop.c                 1158 0x31b3325 
15  IDP_foreach_property                                       idprop.c                 1158 0x31b3325 
16  blender::deg::DepsgraphRelationBuilder::build_idproperties deg_builder_relations.cc 578  0xa34c6eb 
17  blender::deg::DepsgraphRelationBuilder::build_collection   deg_builder_relations.cc 594  0xa34c751 
18  blender::deg::DepsgraphRelationBuilder::build_id           deg_builder_relations.cc 497  0xa34c35e 
19  blender::deg::build_idproperties_callback                  deg_builder_relations.cc 573  0xa34c6b9 
20  IDP_foreach_property                                       idprop.c                 1151 0x31b32e6 
... <More>

So if you remap to something else, no crash occurs

import bpy

class CollectionsSettings(bpy.types.PropertyGroup):
    parent: bpy.props.PointerProperty(name="parent", type=bpy.types.Collection)
    
bpy.utils.register_class(CollectionsSettings)

bpy.types.Collection.prop = bpy.props.PointerProperty(type=CollectionsSettings)

# no crash
cube_col = bpy.data.collections['Cube_coll']
new_col = bpy.data.collections.new('new_col')
third_col = bpy.data.collections.new('third_col')
new_col.prop.parent = cube_col

cube_col.id_data.user_remap(third_col)
Philipp Oeser (lichtwerk) updated the task description. (Show Details)Oct 27 2020, 5:04 PM
Jose Conseco (joseconseco) added a comment.Oct 27 2020, 6:09 PM

Thx @Philipp Oeser (lichtwerk) I may simplified the script too much, but you are right. If I remap 'cube_col' first, then point cube_col to new_col we get no crash (no loop pointer to itself)
However in a bit more complicated case it will still crash:

import bpy

class CollectionsSettings(bpy.types.PropertyGroup):
    parent: bpy.props.PointerProperty(name="parent", type=bpy.types.Collection)
bpy.utils.register_class(CollectionsSettings)

bpy.types.Collection.prop = bpy.props.PointerProperty(type=CollectionsSettings)

# 4 lines below gives crash
cube_col = bpy.data.collections['Cube_coll']
new_col = bpy.data.collections.new('new_col')
cube_col.id_data.user_remap(new_col)                              # remap first so no cyclip loop
new_col.prop.parent = cube_col            # A points to B
cube_col.prop.parent = new_col            # B points to A

I guess you may say there is still loop
new_col points to cube_col ; then cube_col points back to new_col; etc
It worked it 2.82 though. IMO blender could/should check for loop like those.

Bastien Montagne (mont29) added a revision: D9365: Fix T82149: Blender crash when using collection user_id remapping (python)..Oct 27 2020, 7:19 PM
Bastien Montagne (mont29) claimed this task.Oct 27 2020, 7:23 PM
Bastien Montagne (mont29) triaged this task as High priority.
Bastien Montagne (mont29) moved this task from Backlog to Blender 2.91 on the Pipeline, Assets & I/O board.
Bastien Montagne (mont29) edited projects, added BF Blender (2.91); removed BF Blender.
Bastien Montagne (mont29) moved this task from Backlog to bcon3: Bugs on the BF Blender (2.91) board.
Bastien Montagne (mont29) closed this task as Resolved by committing rB0d772221c641: Fix T82149: Blender crash when using collection user_id remapping (python)..Oct 28 2020, 11:08 AM
Bastien Montagne (mont29) added a commit: rB0d772221c641: Fix T82149: Blender crash when using collection user_id remapping (python)..