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  1. Qt
  2. QTBUG-9112

QPixmaps try to access FBS connection after the connection has been closed by QApplication (demonstrated with QtWebKit)

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Details

    • Bug
    • Resolution: Done
    • P2: Important
    • 4.7.1
    • 4.6.2
    • None
    • None
    • f4bada8cbba5f209556ad4e3703d412e4146a0af

    Description

      During QApplication destruction it is possible that FbsBitmap objects are tried to be freed when the font and bitmap server connection has already been closed down. QTimer::singleShot(0, this, SLOT(initialize())); in the test application seems to trigger the crash in destruction phase with more ease. It is not a good way to construct the QT application but seems to be still used in some code code snippet that shows the cleanup order from QApplication.

      QApplication::~QApplication()
      ...
      qt_cleanup();  <-- this closes the FBS connection ...
      qUnregisterGuiVariant(); <-- triggers the child object deletion, where 
      

      QtWebkit's cache deletes QPixmaps Steps to reproduce:

      1) compile the attached sample application
      2) start crash_test application
      3) press end call key to close applications (the sweet spot seems to be when ACID3 test has been executed a bit over 50%)

      Call stack from the panic and test application as attachments. I assume that FBS connection should be closed only after all QObjects are deleted since those could be using QPixmaps that are still trying to access the FBS.

      Attachments

        1. crash_test_qapplication.zip
          1 kB
          Janne Koponen
        2. QApplication_destructor_crash.txt
          8 kB
          Janne Koponen
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            jhautaka Jani Hautakangas
            janne koponen Janne Koponen (Inactive)
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            Dates

              Created:
              Updated:
              Resolved:

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