[Interest] linux: libxcb assertion failure causes program crash

Peter Holzkorn peter.holzkorn at aec.at
Thu Dec 19 18:47:02 CET 2013


My program uses multiple QOpenGLContexts and a Quick context. It crashes 
predictably with a SIGABRT and the following message:

../../src/xcb_conn.c:186: write_vec: Assertion `!c->out.queue_len’ failed.

This bug ( https://bugreports.qt-project.org/browse/QTBUG-31935 ) seems 
to be the same. Neither of the proposed solutions (calling 
XinitThreads(), or patching libxcb as directed, or both) solves the 
problem – the patched version just causes a segfault down the line 
instead of failing the assertion.

The bug is closed (because it’s not a Qt bug) and the only relevant bug 
in xcb is similarly closed (they don’t think it’s xcb’s fault either).

The problem only appears to occur on my laptop (using integrated 
graphics / mesa gl), all on Ubuntu 13.10.

Any help would be appreciated!


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