[Bf-committers] Python context internal state bug

[Jacques Lucke]

Hi all, 

while developing the animation nodes I get a specific error message
quite often in the console: "ERROR: Python context internal state bug.
this should not happen!" 

In the Blender source code this print statement is here:
https://developer.blender.org/diffusion/B/browse/master/source/blender/python/intern/bpy_interface.c$152


What wonders me the most is that everything keeps working I just get
this error message in the console. And not only one time but many
hundred times.
Unfortunally I didn't found a reliable way to reproduce this yet (I try
to find one for weeks already...) but I have some ideas: 

1. The error message always appears first while I was rendering. After
the rendering finishes the message is still printed in the console many
times per second.
2. Until now the error only came when I was doing a mesh animation. That
means my node setup calculates a vertices, edges and polygons and
replaces the mesh data on an existing mesh object in blender with that.
3. Obviusly I use some of the handlers in bpy.app.handlers. All
calculations are done in the scene_update_post event.
4. Just noticed after loading factory settings that the error always
raises when the UI redraws. 

I use Windows 7 64 bit and the error appeared in all of the last Blender
releases. Currently I use 282811f. 

I know that it can be quite hard to find out what raises this error
because I don't have steps to reproduce. Especially because sometimes it
renders all frames fine and sometimes 100 were rendered and then the
error appears although the same code is executed as before. 

Therefor my main question is what triggers this error and why doesn't it
stop when I load factory settings? And if you have an idea what I/you
can do against it.. even better. 

Here is an image showing the error in the console:
http://www.pasteall.org/pic/show.php?id=92952 [1] 

Thanks in advance
Jacques Lucke 
 

Links:
------
[1] http://www.pasteall.org/pic/show.php?id=92952