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  1. Qt
  2. QTBUG-124271

Repeatedly calling QLocale::toString with timezone is slower than it should be

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Details

    • Bug
    • Resolution: Unresolved
    • P3: Somewhat important
    • None
    • 6.7
    • Core: Date/Time
    • None
    • Fedora 39, KDE Plasma
    • Linux/Wayland, Linux/X11

    Description

      When profiling Neochat I found that calling

      new Date().toLocaleString(Qt.locale(), Locale.LongFormat)

      repeatedly contributes a non-negligible amount of cycles to the runtime.

       

      This is because for each invocation the timezone data is recreated, despite it always being the same. It might be worth caching the timezone name lookup somehow.

      Attached is a Flamegraph for

       

      for (int i=0; i<1000; i++) {
    QDateTime time = QDateTime::currentDateTime();
    qWarning() << QLocale().toString(time, QLocale::LongFormat);
}

      Tested with current 6.7 branch

       

      Attachments

        Issue Links

          relates to

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-115158 Time zone names and abbreviations are not localised

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-124465 QDate::fromString very slow in 6.7.0

          • 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

              Eddy Edward Welbourne
              nicolasfella Nicolas Fella
              Vladimir Minenko Vladimir Minenko
              Alex Blasche Alex Blasche
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              Dates

                Created:
                Updated:

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