Crash! Calling a modal operator from a load_post handler causes a segmentation fault #92258

New Issue

Jeducious · 2021-10-16T04:23:47+02:00

Jeducious commented

2021-10-16 04:23:47 +02:00

System Information
Operating system:MacOS
Graphics card:intel iris graphics
system-info.txt

Blender Version
Broken: 3.0 alpha, 2055ef107a, master, 2021-10-14
Worked: Blender 2.93.4

Short description of error
Our addon Crowdrender uses the bpy.apps.handlers.load_post handler to trigger a modal operator. On Blender 2.93 and below, this has worked since 2.80/2.79. However, in the latest alpha versions of Blender 3.0 this now causes a crash when Blender starts.

If the addon is disabled at startup, however, the crash is avoided and the addon can be enabled successfully without a crash once Blender has started. I can also load a new file and Blender remains stable and running. The problem seems to only occur at startup.

The crash report is here -> Mac crash report.rtf

Exact steps for others to reproduce the error
The scene used is irrelevant since Blender is crashing before the user is able to access the UI.

Please find attached a small addon that reproduces the same issue.
load_post_handler_crash.py
To reproduce the problem,

copy the addon to Blender's addons folder
make sure this addon is enabled in Blender's preferences
then save the preferences to make the addon load when Blender starts
restart Blender

Blender crashes on startup

**System Information** Operating system:MacOS Graphics card:intel iris graphics [system-info.txt](https://archive.blender.org/developer/F11157101/system-info.txt) **Blender Version** Broken: 3.0 alpha, 2055ef107a7c, master, 2021-10-14 Worked: Blender 2.93.4 **Short description of error** Our addon [Crowdrender ](https://www.crowd-render.com) uses the bpy.apps.handlers.load_post handler to trigger a modal operator. On Blender 2.93 and below, this has worked since 2.80/2.79. However, in the latest alpha versions of Blender 3.0 this now causes a crash when Blender starts. If the addon is disabled at startup, however, the crash is avoided and the addon can be enabled successfully without a crash once Blender has started. I can also load a new file and Blender remains stable and running. The problem seems to only occur at startup. The crash report is here -> [Mac crash report.rtf](https://archive.blender.org/developer/F11157189/Mac_crash_report.rtf) **Exact steps for others to reproduce the error** The scene used is irrelevant since Blender is crashing before the user is able to access the UI. Please find attached a small addon that reproduces the same issue. [load_post_handler_crash.py](https://archive.blender.org/developer/F11173310/load_post_handler_crash.py) To reproduce the problem, - copy the addon to Blender's addons folder - make sure this addon is enabled in Blender's preferences - then save the preferences to make the addon load when Blender starts - restart Blender # Blender crashes on startup

Jeducious commented

2021-10-16 04:23:47 +02:00

Added subscriber: @JamesCrowther

Ryan Inch commented

2021-10-16 05:58:39 +02:00

Added subscriber: @Imaginer

Erik Abrahamsson commented

2021-10-16 06:28:49 +02:00

Added subscriber: @erik85

Erik Abrahamsson commented

2021-10-16 06:28:49 +02:00

I tried this on Win10 but can't reproduce the crash. I also had to modify the script with from bpy.app.handlers import persistent and @persistent decorator on the handler function to make it run.

I tried this on Win10 but can't reproduce the crash. I also had to modify the script with `from bpy.app.handlers import persistent` and `@persistent` decorator on the handler function to make it run.

Jeducious commented

2021-10-16 14:03:12 +02:00

In #92258#1236621, @erik85 wrote:
I tried this on Win10 but can't reproduce the crash. I also had to modify the script with from bpy.app.handlers import persistent and @persistent decorator on the handler function to make it run.

Yeah, I am on macOS, haven't tried this on win10 yet. Copy that on the need to add the persistent decorator. Not sure why its not in the code I attached, its in my local copy. Could have been I uploaded an older version. Sorry about that :S

> In #92258#1236621, @erik85 wrote: > I tried this on Win10 but can't reproduce the crash. I also had to modify the script with `from bpy.app.handlers import persistent` and `@persistent` decorator on the handler function to make it run. Yeah, I am on macOS, haven't tried this on win10 yet. Copy that on the need to add the persistent decorator. Not sure why its not in the code I attached, its in my local copy. Could have been I uploaded an older version. Sorry about that :S

Jeducious commented

2021-10-16 14:17:36 +02:00

Just updated the attached addon so it has the @persistent decorator. Looks like I moved the file when I was testing it with Blender 3.0.0 and then uploaded the copy from the old location. I have edited the task above and replaced the addon with the one I was able to reproduce the same crash with.

Pratik Borhade commented

2022-01-21 05:34:30 +01:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2022-01-21 05:34:30 +01:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Pratik Borhade commented

2022-01-21 05:34:30 +01:00

Can not reproduce either, tested on current master and 3.0.0(2055ef107a)
Does this still occur for you on latest builds?: https://builder.blender.org/download/daily/
May be you could also add userprefs.blend file to test the crash

Can not reproduce either, tested on current master and 3.0.0(2055ef107a) Does this still occur for you on latest builds?: https://builder.blender.org/download/daily/ May be you could also add `userprefs.blend` file to test the crash

Pratik Borhade commented

2022-02-07 10:19:29 +01:00

Added subscriber: @mano-wii

Pratik Borhade commented

2022-02-07 10:19:29 +01:00

@mano-wii , can you reproduce? Otherwise we can close the task as report went cold for more than a week

Germano Cavalcante commented

2022-02-09 23:04:34 +01:00

Changed status from 'Needs User Info' to: 'Archived'

Germano Cavalcante closed this issue

2022-02-09 23:04:34 +01:00

Germano Cavalcante commented

2022-02-09 23:04:35 +01:00

I cannot reproduce the problem.
The operator runs normally and intermittently (which is not a good practice as, among other things, it makes Auto Save impossible).

System Information
Operating system: macOS-12.2-arm64-arm-64bit 64 Bits
Graphics card: Apple M1 Apple 4.1 Metal - 76.3

I cannot reproduce the problem. The operator runs normally and intermittently (which is not a good practice as, among other things, it makes Auto Save impossible). --- **System Information** Operating system: `macOS-12.2-arm64-arm-64bit 64 Bits` Graphics card: `Apple M1 Apple 4.1 Metal - 76.3`

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Crash! Calling a modal operator from a load_post handler causes a segmentation fault #92258

Blender crashes on startup