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  1. Qt
  2. QTBUG-77952

[REG: 5.11 -> 5.12]: QGraphicsView gets very slow with many update() calls

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    • 31012df705c37503be00f0ddc2c323e73fd28067 (qt/qtbase/5.13)

      Looks like the fix for QTBUG-54275 ( " QGraphicsScene::update(): Keep the list of updatedRects() unique" 1d09b0d1b28eaea17069f7359956640f31ea79c6 https://codereview.qt-project.org/c/qt/qtbase/+/241098 ) causes update() call to get very slow due to it scanning the whole list. qFuzzyCompare and especially qAbs is showing up quite high in a profiler.

      With attached minimal example, press the button and it will freeze for a while.

      On my system, Qt 5.11.3 completes in 9ms, but Qt 5.12.4 takes over 6 seconds.

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        For Gerrit Dashboard: QTBUG-77952
        # Subject Branch Project Status CR V
        272462,13 Fix QGraphicsScene::update() performance 5.13 qt/qtbase Status: MERGED +2 0
        273834,5 Add a benchmark for QGraphicsScene::update() 5.13 qt/qtbase Status: ABANDONED -1 0

            anrocha André De La Rocha (Inactive)
            poikelin Joni Poikelin
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              Created:
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              Resolved:

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