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Assert in XAllocId called from XCreatePixmap on Ubuntu 12.04

  • Hi Qt

    I have an app that is hitting an assert in XAllocID. I have done some searching and found the following which appears to match it quite closely: Unfortunately, this bug is still open (and was reported in 2011!).

    The backtrace looks like this:

    (gdb) bt
    #0 0xb7782424 in __kernel_vsyscall ()
    #1 0xb5629e0f in raise () from /lib/i386-linux-gnu/
    #2 0xb562d455 in abort () from /lib/i386-linux-gnu/
    #3 0xb5622cb5 in ?? () from /lib/i386-linux-gnu/
    #4 0xb5622d67 in __assert_fail () from /lib/i386-linux-gnu/
    #5 0xb5cd649f in _XAllocID () from /usr/nvr/sharedlib/
    #6 0xb5cb3ef2 in XCreatePixmap () from /usr/nvr/sharedlib/
    #7 0xb60ab5d5 in QPixmap::init(int, int, int, bool, QPixmap::Optimization) () from /usr/nvr/sharedlib/
    #8 0xb615ccb5 in QPixmap::QPixmap(int, int, int, QPixmap::Optimization) () from /usr/nvr/sharedlib/
    #9 0xb60fd19b in QBitmap::QBitmap(int, int, bool, QPixmap::Optimization) () from /usr/nvr/sharedlib/
    #10 0xb60bbbc1 in QPainter::drawPixmap(int, int, QPixmap const&, int, int, int, int) () from /usr/nvr/sharedlib/
    #11 ... application code ....

    In my case the application can run for weeks, but it usually takes 3 to 5 days to hit the assert.

    It's a video application that displays a number of video streams. Nothing else is done to the system. It is simply left showing the video streams, and after a while it exits.

    The software runs on Windows (obviously won't have the same problem), Fedora 16, Ubuntu 12.04 and various versions of NetBSD. The problem has only been seen on Ubuntu 12.04.

    So while it appears to only happen on Ubuntu I was wondering if the Qt guys had seen this before, and if they had any advice for dealing with it. If this is the wrong forum please can you redirect me.

    Many thanks

  • Lifetime Qt Champion

    Hi and welcome to devnet,

    You should rather try the interest mailing list. You'll find there Qt's developers/maintainers. This forum use more user oriented.

  • Thank you. I've posted to the Qt Linux group

  • Lifetime Qt Champion

    Qt Linux group ?

  • Ok, I joined the Qt Linux group ( and thought I had posted to them. Forgive the newbie :-)

    I've now subscribed to the qt interest mailing list and posted there

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