[Development] [Qt-5.6] leak of QtSharedPointer::ExternalRefCountData objects
Liang Jian
jianliang79 at gmail.com
Sun Nov 15 15:19:48 CET 2015
Hello everyone, I checkout qt 5.6 branch yesterday in my windows 10
x64 machine, I build it and run my program and see many leaks. Then I use C++
Memory Validator to find the source of the leaks, I can now confirm the
leaked objects are QtSharedPointer::ExternalRefCountData which are created
in QQmlObjectCreator::createInstance(), qqmlobjectcreator.cpp Line 1049,
below is the call stack printed by C++ Memory Validator:
Qt5Cored.dll QtSharedPointer::ExternalRefCountData::getAndRef :
[d:\qt5\qtbase\src\corelib\tools\qsharedpointer.cpp Line 1337]
Qt5Qmld.dll QWeakPointer<QObject>::QWeakPointer<QObject><QObject> :
[d:\qt5\qtbase\src\corelib\tools\qsharedpointer_impl.h Line 706]
Qt5Qmld.dll QPointer<QObject>::QPointer<QObject> :
[d:\qt5\qtbase\src\corelib\kernel\qpointer.h Line 65]
Qt5Qmld.dll QQmlObjectCreator::createInstance :
[d:\qt5\qtdeclarative\src\qml\qml\qqmlobjectcreator.cpp Line 1049]
1044 : QQmlData *ddata = QQmlData::get(instance,
/*create*/true);
1045 : ddata->rootObjectInCreation = true;
1046 : sharedState->rootContext->isRootObjectInCreation
= false;
1047 : }
1048 :
1049 : sharedState->allCreatedObjects.push(instance);
1050 : } else {
1051 : Q_ASSERT(typeRef->component);
1052 : Q_QML_OC_PROFILE(sharedState->profiler,
profiler.update(typeRef->component->fileName(),
1053 : context->url(), obj->location.line,
obj->location.column));
1054 : if
(typeRef->component->compilationUnit->data->isSingleton())
Qt5Qmld.dll QQmlObjectCreator::create :
[d:\qt5\qtdeclarative\src\qml\qml\qqmlobjectcreator.cpp Line 197]
Qt5Qmld.dll QQmlComponentPrivate::beginCreate :
[d:\qt5\qtdeclarative\src\qml\qml\qqmlcomponent.cpp Line 863]
Qt5Qmld.dll QQmlComponent::beginCreate :
[d:\qt5\qtdeclarative\src\qml\qml\qqmlcomponent.cpp Line 812]
Qt5Qmld.dll QQmlComponent::create :
[d:\qt5\qtdeclarative\src\qml\qml\qqmlcomponent.cpp Line 772]
Qt5Quickd.dll QQuickView::continueExecute :
[d:\qt5\qtdeclarative\src\quick\items\qquickview.cpp Line 486]
Qt5Quickd.dll QQuickViewPrivate::execute :
[d:\qt5\qtdeclarative\src\quick\items\qquickview.cpp Line 127]
Qt5Quickd.dll QQuickView::setSource :
[d:\qt5\qtdeclarative\src\quick\items\qquickview.cpp Line 256]
All the leaked QtSharedPointer::ExternalRefCountData objects are
allocated in the line
sharedState->allCreatedObjects.push(instance);
then some other code path will also use QPointer (contained in some
structures allocated by v4mm) to track the same object 'instance' and I
guess the QPointer wasn't properly destructed which will cause the
QtSharedPointer::ExternalRefCountData
not deleted.
I have investigated this issue for nearly one day, but I can't find
which code cause the leak, this is a non-trivial leak, I hope somebody can
help to find the source of the leak. thanks!
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