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  1. Qt for Python
  2. PYSIDE-1657

Possible deadlock on signal connect/emit

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Not Evaluated
    • Resolution: Fixed
    • Affects Version/s: 5.14.1
    • Fix Version/s: 5.14.2.2
    • Component/s: PySide
    • Labels:
      None
    • Environment:
      MacOs v11.1 (BigSur), PySide2 5.14.1, Python 2.7.
    • Platform/s:
      macOS

      Description

      Deadlocks in multi threaded applications can happen on signal emit/connect depending on the order of GIL and QObject lock acquisition.

      The problem looks very similar to this issue which was fixed for PySide, but possibly not for PySide2.

      https://bugreports.qt.io/browse/PYSIDE-164

      https://codereview.qt-project.org/c/pyside/pyside-setup/+/84454

       

      Unfortunately it is very hard to provide a script to reproduce the issue. But if you look at the attached process sample, you can see that:

      • The main thread is trying to connect a signal, and possibly acquired the GIL.
      • Thread Thread_356690 is trying to emit a signal and is waiting for the GIL to be released, but is possibly holding the lock the main thread is trying to acquire.

      This problem does not happen at all with PySide 1.2.4.

       

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          relates to

          Bug - A problem which impairs or prevents the functions of the product. PYSIDE-803 QThread Freezes GUI

          • P1: Critical - Urgent and Important, will STOP the release if matched with set FixVersion field. This includes regressions from the last version that are not edge cases; Data loss; Build issues; All but the most unlikely crashes/lockups/hanging; Serious usability issues and embarrassing bugs & Bugs critical to a deliverable. This is the highest possible priority for requirements.
          • Closed
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            Activity

              People

              Assignee:
              crmaurei Cristian Maureira-Fredes
              Reporter:
              gplsteph Stéphane Deverly
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                Dates

                Created:
                Updated:
                Resolved:

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