Dependency graph update_post handler trigger maximum recursion depth error #65155

New Issue

domlysz · 2019-05-26T17:37:05+02:00

domlysz commented

2019-05-26 17:37:05 +02:00

System Information
Operating system: Linux Ubuntu 64bits
Graphics card: /

Blender Version
Broken: Blender 2.8, 2019-05-25
Worked: Blender 2.8, 2019-04-30

Short description of error
When multiple addons append their own depsgraph_update_post handler then it causes a maximum recursion depth error

Exact steps for others to reproduce the error
here a simple code that illustrate the issue

import bpy
from bpy.app.handlers import persistent

@persistent
def scene_update(scn):
    obj = bpy.context.view_layer.objects.active
    if obj is not None:
        print(obj.name)

@persistent
def scene_update2(scn):
    pass
        
bpy.app.handlers.depsgraph_update_post.append(scene_update)
bpy.app.handlers.depsgraph_update_post.append(scene_update2)

This code add a new handler that print the active object's name when the selection change. The code works correctly but if another handlers is appended then clicking on the cube of the default scene print it's name dozens of times and sometimes triggering a maximum recursion depth error. Seems there is no issue when selecting the light or the camera.

**System Information** Operating system: Linux Ubuntu 64bits Graphics card: / **Blender Version** Broken: Blender 2.8, 2019-05-25 Worked: Blender 2.8, 2019-04-30 **Short description of error** When multiple addons append their own *depsgraph_update_post* handler then it causes a maximum recursion depth error **Exact steps for others to reproduce the error** here a simple code that illustrate the issue ``` import bpy from bpy.app.handlers import persistent @persistent def scene_update(scn): obj = bpy.context.view_layer.objects.active if obj is not None: print(obj.name) @persistent def scene_update2(scn): pass bpy.app.handlers.depsgraph_update_post.append(scene_update) bpy.app.handlers.depsgraph_update_post.append(scene_update2) ``` This code add a new handler that print the active object's name when the selection change. The code works correctly but if another handlers is appended then clicking on the cube of the default scene print it's name dozens of times and sometimes triggering a maximum recursion depth error. Seems there is no issue when selecting the light or the camera.

domlysz commented

2019-05-26 17:37:05 +02:00

Added subscriber: @domlysz

Ross Edwards commented

2019-05-26 20:50:48 +02:00

Added subscriber: @RossEdwards

Jacques Lucke commented

2019-05-27 12:21:27 +02:00

Added subscriber: @JacquesLucke

Jacques Lucke commented

2019-05-27 12:21:27 +02:00

I cannot reproduce the issue using the given code.

However, in general you should protect yourself against recursions when using these handlers afaik.

I cannot reproduce the issue using the given code. However, in general you should protect yourself against recursions when using these handlers afaik.

Brecht Van Lommel commented

2019-05-29 01:52:21 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2019-05-29 01:52:21 +02:00

I can't reproduce recursion depth errors with this Python script, and it's not clear to me how it could happen here.

What are the exact steps to reproduce this problem? Just run the script and select some objects in the viewport?

I can't reproduce recursion depth errors with this Python script, and it's not clear to me how it could happen here. What are the exact steps to reproduce this problem? Just run the script and select some objects in the viewport?

domlysz commented

2019-05-29 11:56:59 +02:00

Thanks for the feeback.

I can confirm that theses steps are not enough to reproduce this error. The initial issue was raised on my own addon's github and concern a conflict with another addon that also use a depsgraph_update_post handler. My addon works correctly as it but raise a recursion depth error only if the other addon is enabled. I'm trying to isolate the issue because I don't undersand what's wrong in my code, but the proposed snipped above fails only if my addon is still enabled.

So, I propose to close this task because for now I can't determine if there is something wrong in my code or in the depsgraph api.

For reference

the initial issue : https://github.com/domlysz/BlenderGIS/issues/173
the handler callback causing the issue : 77ba35311c/operators/nodes_terrain_analysis_reclassify.py (L147)

Thanks for the feeback. I can confirm that theses steps are not enough to reproduce this error. The initial issue was raised on my own addon's github and concern a conflict with another addon that also use a *depsgraph_update_post* handler. My addon works correctly as it but raise a recursion depth error only if the other addon is enabled. I'm trying to isolate the issue because I don't undersand what's wrong in my code, but the proposed snipped above fails only if my addon is still enabled. So, I propose to close this task because for now I can't determine if there is something wrong in my code or in the depsgraph api. For reference - the initial issue : https://github.com/domlysz/BlenderGIS/issues/173 - the handler callback causing the issue : https://github.com/domlysz/BlenderGIS/blob/77ba35311cde4d17dd276d7badc02389bab767a5/operators/nodes_terrain_analysis_reclassify.py#L147

Brecht Van Lommel commented

2019-05-29 11:59:44 +02:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2019-05-29 11:59:44 +02:00

Brecht Van Lommel self-assigned this 2019-05-29 11:59:44 +02:00

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Dependency graph update_post handler trigger maximum recursion depth error #65155