SUMMARY When a user exits KDevelop right after a large project is opened, before ProjectFileDataProvider::projectOpened() slot returns, IProjectController::projectClosing() signal is emitted before some slots connected to IProjectController::projectOpened() signal ale invoked (more precisely, the slots that were connected to projectOpened() signal later than the ProjectFileDataProvider::projectOpened() slot). Thus a valid assumption that a slot connected to projectOpened() is always called before a slot connected to projectClosing() becomes incorrect and causes a segmentation fault in ClassModel::removeProjectNode(). STEPS TO REPRODUCE 1. Open a large project with tens of thousands of files, such as KDevelop itself. 2. Exit KDevelop as soon as the just opened project appears in Projects tool view. SOFTWARE/OS VERSIONS Manjaro GNU/Linux, Xfce KDE Frameworks Version: 5.74.0 Qt Version: 5.15.1 ADDITIONAL INFORMATION I am going to create a Merge Request with a fix soon. BACKTRACE (RelWithDebInfo) Application: KDevelop (kdevelop), signal: Segmentation fault Using host libthread_db library "/usr/lib/libthread_db.so.1". [Current thread is 1 (Thread 0x7f3bdd900580 (LWP 40040))] Thread 1 (Thread 0x7f3bdd900580 (LWP 40040)): [KCrash Handler] #6 0x00007f3bf519a711 in ClassModelNodes::Node::row() (this=0x0) at ../kdevplatform/language/classmodel/classmodelnode.cpp:487 #7 0x00007f3bf519a514 in ClassModelNodes::Node::removeNode(ClassModelNodes::Node*) (this=0x559e9ad20ae0, a_child=0x0) at ../kdevplatform/language/classmodel/classmodelnode.cpp:446 #8 0x00007f3bf51967c0 in ClassModel::removeProjectNode(KDevelop::IProject*) (this=0x559e9ad20aa0, project=0x559e9d2c3760) at ../kdevplatform/language/classmodel/classmodel.cpp:272 #9 0x00007f3bf5197fa9 in QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<KDevelop::IProject*>, void, void (ClassModel::*)(KDevelop::IProject*)>::call(void (ClassModel::*)(KDevelop::IProject*), ClassModel*, void**) (f=(void (ClassModel::*)(ClassModel * const, KDevelop::IProject *)) 0x7f3bf5196772 <ClassModel::removeProjectNode(KDevelop::IProject*)>, o=0x559e9ad20aa0, arg=0x7ffc5526f790) at /usr/include/qt/QtCore/qobjectdefs_impl.h:152 #10 0x00007f3bf5197dfd in QtPrivate::FunctionPointer<void (ClassModel::*)(KDevelop::IProject*)>::call<QtPrivate::List<KDevelop::IProject*>, void>(void (ClassModel::*)(KDevelop::IProject*), ClassModel*, void**) (f=(void (ClassModel::*)(ClassModel * const, KDevelop::IProject *)) 0x7f3bf5196772 <ClassModel::removeProjectNode(KDevelop::IProject*)>, o=0x559e9ad20aa0, arg=0x7ffc5526f790) at /usr/include/qt/QtCore/qobjectdefs_impl.h:185 #11 0x00007f3bf519791a in QtPrivate::QSlotObject<void (ClassModel::*)(KDevelop::IProject*), QtPrivate::List<KDevelop::IProject*>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (which=1, this_=0x559e9ad1d730, r=0x559e9ad20aa0, a=0x7ffc5526f790, ret=0x0) at /usr/include/qt/QtCore/qobjectdefs_impl.h:414 #12 0x00007f3bf21fd50e in () at /usr/lib/libQt5Core.so.5 #13 0x00007f3bf4cc18da in KDevelop::IProjectController::projectClosing(KDevelop::IProject*) (this=0x559e97168110, _t1=0x559e9d2c3760) at kdevplatform/interfaces/KDevPlatformInterfaces_autogen/EWIEGA46WW/moc_iprojectcontroller.cpp:273 #14 0x00007f3bf61ed683 in KDevelop::ProjectController::takeProject(KDevelop::IProject*) (this=0x559e97168110, proj=0x559e9d2c3760) at ../kdevplatform/shell/projectcontroller.cpp:1070 #15 0x00007f3bf61ed759 in KDevelop::ProjectController::closeProject(KDevelop::IProject*) (this=0x559e97168110, proj=0x559e9d2c3760) at ../kdevplatform/shell/projectcontroller.cpp:1090 #16 0x00007f3bf61ed81e in KDevelop::ProjectController::closeAllProjects() (this=0x559e97168110) at ../kdevplatform/shell/projectcontroller.cpp:1100 #17 0x00007f3bf61ea918 in KDevelop::ProjectController::cleanup() (this=0x559e97168110) at ../kdevplatform/shell/projectcontroller.cpp:665 #18 0x00007f3bf61d9c6d in KDevelop::Core::cleanup() (this=0x559e97676230) at ../kdevplatform/shell/core.cpp:395 #19 0x00007f3bf61d996e in KDevelop::Core::shutdown() (this=0x559e97676230) at ../kdevplatform/shell/core.cpp:356 #20 0x00007f3bf61b47e3 in KDevelop::MainWindow::~MainWindow() (this=0x559e97695730, __in_chrg=<optimized out>, __vtt_parm=<optimized out>) at ../kdevplatform/shell/mainwindow.cpp:150 #21 0x00007f3bf61b48a6 in KDevelop::MainWindow::~MainWindow() (this=0x559e97695730, __in_chrg=<optimized out>, __vtt_parm=<optimized out>) at ../kdevplatform/shell/mainwindow.cpp:154 #22 0x00007f3bf21f50a0 in QObject::event(QEvent*) () at /usr/lib/libQt5Core.so.5 #23 0x00007f3bf30ac439 in QWidget::event(QEvent*) () at /usr/lib/libQt5Widgets.so.5 #24 0x00007f3bf31c6515 in QMainWindow::event(QEvent*) () at /usr/lib/libQt5Widgets.so.5 #25 0x00007f3bf3d1fefc in KMainWindow::event(QEvent*) () at /usr/lib/libKF5XmlGui.so.5 #26 0x00007f3bf3d6b578 in KXmlGuiWindow::event(QEvent*) () at /usr/lib/libKF5XmlGui.so.5 #27 0x00007f3bf61b4de3 in KDevelop::MainWindow::event(QEvent*) (this=0x559e97695730, ev=0x559e9d3a63e0) at ../kdevplatform/shell/mainwindow.cpp:208 #28 0x00007f3bf3068362 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5 #29 0x00007f3bf3071819 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5 #30 0x00007f3bf21c7a12 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5 #31 0x00007f3bf21ca276 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib/libQt5Core.so.5 #32 0x00007f3bf2220a84 in () at /usr/lib/libQt5Core.so.5 #33 0x00007f3befcfd9be in g_main_context_dispatch () at /usr/lib/libglib-2.0.so.0 #34 0x00007f3befcff831 in () at /usr/lib/libglib-2.0.so.0 #35 0x00007f3befcff871 in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0 #36 0x00007f3bf2220143 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5 #37 0x00007f3bc59b7124 in ProjectFileDataProvider::projectOpened(KDevelop::IProject*) (this=0x559e98cdbb00, project=0x559e9d2c3760) at ../plugins/quickopen/projectfilequickopen.cpp:248 #38 0x00007f3bc59c092f in QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<KDevelop::IProject*>, void, void (ProjectFileDataProvider::*)(KDevelop::IProject*)>::call(void (ProjectFileDataProvider::*)(KDevelop::IProject*), ProjectFileDataProvider*, void**) (f=(void (ProjectFileDataProvider::*)(ProjectFileDataProvider * const, KDevelop::IProject *)) 0x7f3bc59b702e <ProjectFileDataProvider::projectOpened(KDevelop::IProject*)>, o=0x559e98cdbb00, arg=0x7ffc552702f0) at /usr/include/qt/QtCore/qobjectdefs_impl.h:152 #39 0x00007f3bc59bf2fe in QtPrivate::FunctionPointer<void (ProjectFileDataProvider::*)(KDevelop::IProject*)>::call<QtPrivate::List<KDevelop::IProject*>, void>(void (ProjectFileDataProvider::*)(KDevelop::IProject*), ProjectFileDataProvider*, void**) (f=(void (ProjectFileDataProvider::*)(ProjectFileDataProvider * const, KDevelop::IProject *)) 0x7f3bc59b702e <ProjectFileDataProvider::projectOpened(KDevelop::IProject*)>, o=0x559e98cdbb00, arg=0x7ffc552702f0) at /usr/include/qt/QtCore/qobjectdefs_impl.h:185 #40 0x00007f3bc59bdbc4 in QtPrivate::QSlotObject<void (ProjectFileDataProvider::*)(KDevelop::IProject*), QtPrivate::List<KDevelop::IProject*>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (which=1, this_=0x559e98cdcaf0, r=0x559e98cdbb00, a=0x7ffc552702f0, ret=0x0) at /usr/include/qt/QtCore/qobjectdefs_impl.h:414 #41 0x00007f3bf21fd50e in () at /usr/lib/libQt5Core.so.5 #42 0x00007f3bf4cc1864 in KDevelop::IProjectController::projectOpened(KDevelop::IProject*) (this=0x559e97168110, _t1=0x559e9d2c3760) at kdevplatform/interfaces/KDevPlatformInterfaces_autogen/EWIEGA46WW/moc_iprojectcontroller.cpp:266 #43 0x00007f3bf61ecf38 in KDevelop::ProjectController::projectImportingFinished(KDevelop::IProject*) (this=0x559e97168110, project=0x559e9d2c3760) at ../kdevplatform/shell/projectcontroller.cpp:1000 #44 0x00007f3bf62058a3 in KDevelop::ProjectPrivate::importDone(KJob*) (this=0x559e9d2c5a00, job=0x559e9cb327c0) at ../kdevplatform/shell/project.cpp:221 #45 0x00007f3bf62030e4 in KDevelop::Project::<lambda(KJob*)>::operator()(KJob *) const (__closure=0x559e9cb36f10, job=0x559e9cb327c0) at ../kdevplatform/shell/project.cpp:548 #46 0x00007f3bf620525b in QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<KJob*>, void, KDevelop::Project::open(const KDevelop::Path&)::<lambda(KJob*)> >::call(KDevelop::Project::<lambda(KJob*)> &, void **) (f=..., arg=0x7ffc552705b0) at /usr/include/qt/QtCore/qobjectdefs_impl.h:146 #47 0x00007f3bf62051b3 in QtPrivate::Functor<KDevelop::Project::open(const KDevelop::Path&)::<lambda(KJob*)>, 1>::call<QtPrivate::List<KJob*>, void>(KDevelop::Project::<lambda(KJob*)> &, void *, void **) (f=..., arg=0x7ffc552705b0) at /usr/include/qt/QtCore/qobjectdefs_impl.h:256 #48 0x00007f3bf6205157 in QtPrivate::QFunctorSlotObject<KDevelop::Project::open(const KDevelop::Path&)::<lambda(KJob*)>, 1, QtPrivate::List<KJob*>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void **, bool *) (which=1, this_=0x559e9cb36f00, r=0x559e9d2c3760, a=0x7ffc552705b0, ret=0x0) at /usr/include/qt/QtCore/qobjectdefs_impl.h:439 #49 0x00007f3bf21fd50e in () at /usr/lib/libQt5Core.so.5 #50 0x00007f3bf26f4e4d in KJob::result(KJob*, KJob::QPrivateSignal) () at /usr/lib/libKF5CoreAddons.so.5 #51 0x00007f3bf26f593c in KJob::finishJob(bool) () at /usr/lib/libKF5CoreAddons.so.5 #52 0x00007f3bf4d2f52a in KDevelop::ExecuteCompositeJob::slotResult(KJob*) (this=0x559e9cb327c0, job=0x559e9ccb82b0) at ../kdevplatform/util/executecompositejob.cpp:129 #53 0x00007f3bf21fd50e in () at /usr/lib/libQt5Core.so.5 #54 0x00007f3bf26f4e4d in KJob::result(KJob*, KJob::QPrivateSignal) () at /usr/lib/libKF5CoreAddons.so.5 #55 0x00007f3bf26f593c in KJob::finishJob(bool) () at /usr/lib/libKF5CoreAddons.so.5 #56 0x00007f3bf1948aa5 in KDevelop::FileManagerListJob::handleResults(QList<KIO::UDSEntry> const&) (this=0x559e9ccb82b0, entriesIn=...) at ../kdevplatform/project/filemanagerlistjob.cpp:196 #57 0x00007f3bf1914a43 in KDevelop::FileManagerListJob::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) (_o=0x559e9ccb82b0, _c=QMetaObject::InvokeMetaMethod, _id=4, _a=0x559e9d5bbc48) at kdevplatform/project/KDevPlatformProject_autogen/EWIEGA46WW/moc_filemanagerlistjob.cpp:108 #58 0x00007f3bf21f530a in QObject::event(QEvent*) () at /usr/lib/libQt5Core.so.5 #59 0x00007f3bf3068362 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5 #60 0x00007f3bf3071819 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5 #61 0x00007f3bf21c7a12 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5 #62 0x00007f3bf21ca276 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () at /usr/lib/libQt5Core.so.5 #63 0x00007f3bf2220a84 in () at /usr/lib/libQt5Core.so.5 #64 0x00007f3befcfd9be in g_main_context_dispatch () at /usr/lib/libglib-2.0.so.0 #65 0x00007f3befcff831 in () at /usr/lib/libglib-2.0.so.0 #66 0x00007f3befcff871 in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0 #67 0x00007f3bf22200d0 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5 #68 0x00007f3bf21c657c in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5 #69 0x00007f3bf21ce586 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5 #70 0x0000559e96202588 in main(int, char**) (argc=3, argv=0x7ffc55271218) at ../app/main.cpp:850 [Inferior 1 (process 40040) detached]
Git commit 3f1b6392cb528d7b8986ab9a0a641cd9e346ef8d by Igor Kushnir. Committed on 13/02/2021 at 08:36. Pushed by igorkushnir into branch 'master'. Don't process events in ProjectFileDataProvider::projectOpened() When a user exits KDevelop or closes the just opened project in the ProjectFileDataProvider::projectOpened()'s nested event loop, IProjectController::projectClosing() signal is emitted before some slots connected to IProjectController::projectOpened() signal ale invoked (more precisely, the slots that were connected to projectOpened() signal later than the ProjectFileDataProvider::projectOpened() slot). Thus a valid assumption that a slot connected to projectOpened() is always called before a slot connected to projectClosing() becomes incorrect and causes a crash, e.g. a segmentation fault in ClassModel::removeProjectNode(). In addition, ProjectController::projectImportingFinished() calls reparseProject() after emitting the projectOpened() signal. Delaying this call until after the project is closed and possibly destroyed would likely case a crash or some other bug. Queuing the slow code and its associated QApplication::processEvents() instead of calling it directly in ProjectFileDataProvider::projectOpened() would not eliminate the crash, but move the segmentation fault from an unrelated class to ProjectFileDataProvider::fileAddedToSet(). When the user disables the Quick Open plugin in this projectOpened()'s nested event loop, a similar crash occurs. These crashes could be fixed by checking whether the project is still open and checking QPointer{this} after the call to QApplication::processEvents(). But the code wouldn't become crash-proof even then. ProjectFileDataProvider should not enter a nested event loop while iterating over the project tree, because a project item can be destroyed during the event loop when a user removes a file, which can make one of the pointers to ProjectBaseItem held by KDevelop::forEachFile() dangling. The benefits of eliminating the nested event loop: 1) no need for verbose crash workarounds; 2) opening projects can be optimized by sorting and merging sorted ranges. In particular, a performance pitfall, when multiple large projects are opened in a certain order, can be eliminated. Related: bug 427379 FIXED-IN: 5.7.0 M +0 -8 plugins/quickopen/projectfilequickopen.cpp https://invent.kde.org/kdevelop/kdevelop/commit/3f1b6392cb528d7b8986ab9a0a641cd9e346ef8d