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  1. Qt
  2. QTBUG-131721

QML type loader thread has data races

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    Description

      QQmlDataBlob is a refcounted data structured used from the engine thread as well as from the type loader thread. Whichever of those drops the last reference will delete it.

      The data blobs are linked to each other with "waitingFor" and "waitingOnMe" links. The "waitingFor" links are refcounted and therefore safe enough for this discussion. The "waitingOnMe" links are not refcounted to avoid reference cycles.

      The dtor of QQmlDataBlob removes the blob to be deleted from all "waitingOnMe" lists of other blobs. This is inherently unsafe. Those lists may be read from on the other thread at the same time.

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          Bug - A problem which impairs or prevents the functions of the product. QTBUG-128269 QQmlEngine destructor hangs on QQmlTypeLoader::invalidate

          • 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
          For Gerrit Dashboard: QTBUG-131721
          # Subject Branch Project Status CR V
          607499,6 QtQml: Fix some type loader threading issues dev qt/qtdeclarative Status: NEW 0 0

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              ulherman Ulf Hermann
              ulherman Ulf Hermann
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