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Details

Type: Bug
Resolution: Fixed
Priority: P1: Critical
Fix Version/s: 6.5.5, 6.6.3, 6.7.0 Beta3, 6.8.0 FF
Affects Version/s: 6.7
Component/s: PDF
Labels:
None

Commits:
8c27ae33f (6.7), e3af0e8ae (6.6), db59042dc (6.5), ed49163c8 (dev), 77d2e9ad3 (6.7), fb8b5abb4 (6.6), 56319fbe0 (6.5)

Description

tst_MultiPageView::pinchDragPinch crashed sometimes when trying to integrate https://codereview.qt-project.org/c/qt/qtwebengine/+/492698

One reason is that the document could be deleted before rendering is done:

1   QPdfDocument::render(int, QSize, QPdfDocumentRenderOptions)                       qpdfdocument.cpp          854 
2   QPdfIOHandler::read(QImage *)                                                     qpdfiohandler.cpp         113 
3   QImageReader::read(QImage *)                                                      qimagereader.cpp          1206
4   readImage(QUrl const&, QIODevice *, QImage *, QString *, QSize *, int *, QRect co qquickpixmapcache.cpp     510 
5   QQuickPixmapReader::processJob(QQuickPixmapReply *, QUrl const&, QString const&,  qquickpixmapcache.cpp     1011
6   QQuickPixmapReader::processJobs()                                                 qquickpixmapcache.cpp     860 
7   ReaderThreadExecutionEnforcer::event(QEvent *)                                    qquickpixmapcache.cpp     759 
8   QCoreApplicationPrivate::notify_helper(QObject *, QEvent *)                       qcoreapplication.cpp      1312
9   doNotify(QObject *, QEvent *)                                                     qcoreapplication.cpp      1239
10  QCoreApplication::notify(QObject *, QEvent *)                                     qcoreapplication.cpp      1222
11  QGuiApplication::notify(QObject *, QEvent *)                                      qguiapplication.cpp       1994
12  QCoreApplication::notifyInternal2(QObject *, QEvent *)                            qcoreapplication.cpp      1138
13  QCoreApplication::sendEvent(QObject *, QEvent *)                                  qcoreapplication.cpp      1581
14  QCoreApplicationPrivate::sendPostedEvents(QObject *, int, QThreadData *)          qcoreapplication.cpp      1936
15  QEventDispatcherUNIX::processEvents(QFlags<QEventLoop::ProcessEventsFlag>)        qeventdispatcher_unix.cpp 415 
16  QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>)                  qeventloop.cpp            100 
17  QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>)                           qeventloop.cpp            191 
18  QThread::exec()                                                                   qthread.cpp               595 
19  QQuickPixmapReader::run()                                                         qquickpixmapcache.cpp     1162
20  QThreadPrivate::start(void *)::$_0::operator()() const                            qthread_unix.cpp          326

one clue is seeing a null d-pointer in the debugger in this case, sometimes.

It no longer occurs on dev branch because of https://codereview.qt-project.org/c/qt/qtwebengine/+/534006 : just don't exit too soon, wait for the rendering to be done. But I'm worried about whether a crash-on-exit is also possible in a real application because of this race condition.