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  1. Qt
  2. QTBUG-93019

[REG 5.15-6.0] QList/QVector regressions

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Details

    • Bug
    • Resolution: Unresolved
    • P1: Critical
    • None
    • 6.0.2, 6.1.0 Beta3
    • Core: Containers and Algorithms
    • None

    Description

      I'm opening a meta-bug to centralize the discussions regarding the behavioral and performance regressions of QList / QVector in Qt 6.0.

      These are causing a number of other bugs, including memory leaks, performance degradations and whole crashes. (See the linked tasks).

      A lot of discussion happened in the gerrit fixes for those bugs, making them hard to find and hard to track (discussions start in one issue and continue in another).

      To summarize some of issues, at this moment:

      • Q6Vector regressed API against Q5Vector: for instance, capacity() contract is now violated due to the prepend space.
      • In general, Q6Vector will soft-leak memory (using more than necessary) because it will grow when prepending with no space on the left (but space available on the right). QTBUG-92912 QTBUG-91801
      • The current implementation of the prepend optimization degenerates on some inputs and triggers OOM. QTBUG-91360

      Attachments

        Issue Links

          relates to

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-92941 REG 5->6: QVector size() does not reach capacity() before reallocating

          • 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.
          • Reported

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-92912 Recursive QTimer:singleshot causes memory leak.

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

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-91360 [REG 5.15-6.0] ListView crash with scrollbar scroll

          • P0: Blocker - MUST be fixed ASAP. This includes issues that prevent/block further Qt development; Legal issues & Serious data loss issues.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-91801 Potential memory leak in sending queued signals?

          • 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

              cnn Qt Core & Network
              peppe Giuseppe D'Angelo
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              Dates

                Created:
                Updated:

                Gerrit Reviews

                  There are no open Gerrit changes