Lambda as scene_update_pre handler may crash Blender upon unload #42005

New Issue

inactive account · 2014-09-29T11:48:05+02:00

inactive account commented

2014-09-29 11:48:05 +02:00

System Information
Windows 7 64-bit, running Blender 2.72 RC:

  Blender 2.72 (sub 0)
      build date: 2014-09-23
      build time: 21:13:05
      build commit date: 2014-09-23
      build commit time: 18:40
      build hash: eb464ee
      build platform: Windows:32bit
      build type: Release

Description of error
Blender crashes (without any error) when unloading a Blend file that registered a lambda function. There are a few "requirements" for this issue:

The registered function must live in a file external to Blender.
The function must be called via a lambda expression.

Here is an example:

"""handler_crash.py"""
import bpy

def echo():
    print("echo")
    return 5

bpy.app.handlers.scene_update_pre.append(lambda _: echo())

Then in the script window in Blender:

import bpy
import sys
sys.path.append(bpy.path.abspath('//'))

This imports the above script. If the script is placed here, Blender handles it properly.
However, by importing it, this bug manifests itself.

import handler_crash

This will crash Blender

bpy.ops.wm.read_homefile()

Exact steps for others to reproduce the error

Save the attached Blend file and .py file
Open the Blend file
Press [ALT] + - [x] to run the script
See crash

handler_crash.py

handler_crash.blend

**System Information** Windows 7 64-bit, running Blender 2.72 RC: ``` Blender 2.72 (sub 0) build date: 2014-09-23 build time: 21:13:05 build commit date: 2014-09-23 build commit time: 18:40 build hash: eb464ee build platform: Windows:32bit build type: Release ``` **Description of error** Blender crashes (without any error) when unloading a Blend file that registered a lambda function. There are a few "requirements" for this issue: - The registered function must live in a file external to Blender. - The function must be called via a lambda expression. Here is an example: ``` """handler_crash.py""" import bpy ``` ``` def echo(): print("echo") return 5 ``` ``` bpy.app.handlers.scene_update_pre.append(lambda _: echo()) ``` Then in the script window in Blender: ``` import bpy import sys sys.path.append(bpy.path.abspath('//')) ``` - This imports the above script. If the script is placed here, Blender handles it properly. - However, by importing it, this bug manifests itself. ``` import handler_crash ``` # This will crash Blender ``` bpy.ops.wm.read_homefile() ``` **Exact steps for others to reproduce the error** 1. Save the attached Blend file and .py file 2. Open the Blend file 3. Press [ALT] + - [x] to run the script 4. See crash [handler_crash.py](https://archive.blender.org/developer/F113553/handler_crash.py) [handler_crash.blend](https://archive.blender.org/developer/F113554/handler_crash.blend)

inactive account commented

2014-09-29 11:48:05 +02:00

Changed status to: 'Open'