Crash on rendering when a python function with GPUOffScreen objects is attached to a frame change handler #77032

New Issue

Paul Jadoul · 2020-05-24T20:41:59+02:00

Paul Jadoul commented

2020-05-24 20:41:59 +02:00

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.74

Blender Version
Broken: version: 2.90 (sub 3), branch: master, commit date: 2020-05-23 21:58, hash: 525fc36a80

Short description of error
When a script with a GPUOffScreen objects is running on a frame change handler, everething is working fine until we render an image. That crashes Blender with that log :

Error : EXCEPTION_ACCESS_VIOLATION
Address : 0x00007FFB44A59248
Module : MSVCP140.dll
Thread : 00001124

Exact steps for others to reproduce the error
Run this script (reduced to the essential to reproduce the crash), than hit F12

  import bpy
  import gpu

  def update(self):
      offscreen = gpu.types.GPUOffScreen(100, 100)
   
  bpy.app.handlers.frame_change_post.append(update)

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.74 **Blender Version** Broken: version: 2.90 (sub 3), branch: master, commit date: 2020-05-23 21:58, hash: `525fc36a80` **Short description of error** When a script with a GPUOffScreen objects is running on a frame change handler, everething is working fine until we render an image. That crashes Blender with that log : Error : EXCEPTION_ACCESS_VIOLATION Address : 0x00007FFB44A59248 Module : MSVCP140.dll Thread : 00001124 **Exact steps for others to reproduce the error** Run this script (reduced to the essential to reproduce the crash), than hit F12 ``` import bpy import gpu ``` ``` def update(self): offscreen = gpu.types.GPUOffScreen(100, 100) bpy.app.handlers.frame_change_post.append(update) ```

Paul Jadoul commented

2020-05-24 20:41:59 +02:00

Added subscriber: @Mixsoupe

Germano Cavalcante commented

2020-05-26 16:35:04 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-05-26 16:35:04 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Germano Cavalcante commented

2020-05-26 16:35:04 +02:00

There are two problems here.

One is that there is no GPUContext active to be used in this context.
The other is that the method for creating GPUOffscreen does not check if there is an active context.

Activating a GPU context in this situation would be complicated, because this callback does not always require it. And it would be an unnecessary overhead for most cases.
Exposing this function to activate context in Python is also a little dangerous.
And with the Render API for python we can work around this problem.

So to solve this, I believe that raising an error in python is enough.

There are two problems here. - One is that there is no GPUContext active to be used in this context. - The other is that the method for creating GPUOffscreen does not check if there is an active context. Activating a GPU context in this situation would be complicated, because this callback does not always require it. And it would be an unnecessary overhead for most cases. Exposing this function to activate context in Python is also a little dangerous. And with the Render API for python we can work around this problem. So to solve this, I believe that raising an error in python is enough.

blender-admin commented

2020-05-26 16:38:09 +02:00

This issue was referenced by 4102e7ed81

This issue was referenced by 4102e7ed81cb2c98dc0ade362f47843c7c13b5a7

Germano Cavalcante commented

2020-05-26 16:38:44 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Germano Cavalcante closed this issue

2020-05-26 16:38:44 +02:00

Germano Cavalcante self-assigned this 2020-05-26 16:38:44 +02:00

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Crash on rendering when a python function with GPUOffScreen objects is attached to a frame change handler #77032