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  1. Qt
  2. QTBUG-88248

QObject orphaned connections soft-leak

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    • c2839843f23fb5c289175cb9577981d48dd273fc

    Description

      Since 5.14 'receiver' QObjects will, on destruction, move its connection in the 'sender' object to an orphaned list, due for cleanup later.

      The orphan list is cleaned up on the sender's next signal emission, or on its destruction.

      In certain circumstances the sender object rarely or never emits signals, and is long-lived. This leads to a long-lived soft leak every time a connection is made to it.

      Can be seen with this example, which is a reduced example of what happens in QNetworkAccessManager:

      int main(int argc, char* argv[])
{
    QCoreApplication qapp(argc, argv);
    QThread th;
    th.start();
    for (int i = 0; i < 1'000'000; ++i) {
        QObject *o = new QObject;
        QObject::connect(&th, &QThread::finished, o, &QObject::deleteLater);
        o->moveToThread(&th);
        QMetaObject::invokeMethod(o, &QObject::deleteLater);
        QThread::msleep(10);
    }
    return 0;
}

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        Issue Links

          duplicates

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-87774 QToolBar::clear() leaks memory

          • 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
          is duplicated by

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-90576 Possible memory leak in TextInput

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

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-86368 QQmlContext leak when connecting to and destroying dynamically created object

          • 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

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-88063 Memory leak in QNetworkAccessManager from QMetaObjectPrivate::connect

          • 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

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-88587 QQuickWidget object stay in QML Engine cache after deletion

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

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-90576 Possible memory leak in TextInput

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

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-106025 REG: isSignalConnected creates a dead lock.

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Closed
          For Gerrit Dashboard: QTBUG-88248
          # Subject Branch Project Status CR V
          320789,15 QObject: cleanup the orphaned connection lists on destruction dev qt/qtbase Status: MERGED +2 0
          322683,18 Fix crash in concurrent disconnect dev qt/qtbase Status: MERGED +2 0
          355074,2 Fix crash in concurrent disconnect 6.2 qt/qtbase Status: MERGED +2 0
          355075,2 Fix crash in concurrent disconnect 6.1 qt/qtbase Status: MERGED +2 0
          355076,4 QObject: cleanup the orphaned connection lists on destruction 6.1 qt/qtbase Status: MERGED +2 0
          355077,4 QObject: cleanup the orphaned connection lists on destruction 6.2 qt/qtbase Status: MERGED +2 0
          355085,2 Fix crash in concurrent disconnect tqtc/lts-5.15 qt/tqtc-qtbase Status: ABANDONED 0 0
          355086,2 QObject: cleanup the orphaned connection lists on destruction tqtc/lts-5.15 qt/tqtc-qtbase Status: ABANDONED +2 0
          363027,9 Fix crash in concurrent disconnect tqtc/lts-5.15 qt/tqtc-qtbase Status: MERGED +2 0

          Activity

            People

              fabiankosmale Fabian Kosmale
              manordheim Mårten Nordheim
              Vladimir Minenko Vladimir Minenko
              Alex Blasche Alex Blasche
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              31 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved: