> On Jan. 12, 2016, 10:49 p.m., David Faure wrote:
> > Can I see the backtrace, with a description of how this gets triggered? I'm
> > not sure the issue is fully understood (as shown by the use of "might" in
> > the description...).
> >
> > Is the action being destroyed by clicking into a submenu of the action?
> > Otherwise I don't get the relation with the fix.
>
> René J.V. Bertin wrote:
> A CrashReporter backtrace I still had logged:
>
> ```
> Exception Type: EXC_BAD_ACCESS (SIGSEGV)
> Exception Codes: EXC_I386_GPFLT
>
> Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
> 0 org.qt-project.QtCore 0x000000010cbac886
> QObject::property(char const*) const + 150 (qlist.h:105)
> 1 libqcocoa.dylib 0x000000011189e37a
> QCocoaMenuItem::~QCocoaMenuItem() + 58 (qcocoamenuitem.mm:109)
> 2 libqcocoa.dylib 0x000000011189e52e
> QCocoaMenuItem::~QCocoaMenuItem() + 14 (qcocoamenuitem.mm:106)
> 3 org.qt-project.QtWidgets 0x000000010b2989bd
> QMenu::actionEvent(QActionEvent*) + 749 (qmenu.cpp:3224)
> 4 org.qt-project.QtWidgets 0x000000010b1643d0
> QWidget::event(QEvent*) + 1232 (qwidget.cpp:9044)
> 5 org.qt-project.QtWidgets 0x000000010b296bdc
> QMenu::event(QEvent*) + 1164 (qmenu.cpp:2678)
> 6 org.qt-project.QtWidgets 0x000000010b12653b
> QApplicationPrivate::notify_helper(QObject*, QEvent*) + 251
> (qapplication.cpp:3716)
> 7 org.qt-project.QtWidgets 0x000000010b1298f4
> QApplication::notify(QObject*, QEvent*) + 8212 (qapplication.cpp:3681)
> 8 org.qt-project.QtCore 0x000000010cb7b433
> QCoreApplication::notifyInternal(QObject*, QEvent*) + 115 (qthread_p.h:291)
> 9 org.qt-project.QtWidgets 0x000000010b1582ed
> QWidget::removeAction(QAction*) + 125 (qcoreapplication.h:224)
> 10 org.qt-project.QtWidgets 0x000000010b11c711
> QAction::~QAction() + 97 (qaction.cpp:566)
> 11 org.qt-project.QtWidgets 0x000000010b16d16c
> QWidgetAction::~QWidgetAction() + 444 (qwidgetaction.cpp:122)
> 12 libKF5WidgetsAddons.5.dylib 0x000000010acddd80
> KSelectAction::~KSelectAction() + 64 (kselectaction.cpp:99)
> 13 org.qt-project.QtCore 0x000000010cba3d75
> QObjectPrivate::deleteChildren() + 245 (qobject.cpp:1943)
> 14 org.qt-project.QtWidgets 0x000000010b153ee1
> QWidget::~QWidget() + 1441 (qwidget.cpp:1658)
> 15 0x00000001093c16bb Bin::~Bin()
> + 1067 (bin.cpp:456)
> 16 0x00000001093c181e Bin::~Bin()
> + 14 (bin.cpp:438)
> 17 0x0000000109443d3e
> Core::~Core() + 62 (core.cpp:43)
> 18 0x000000010940c95f
> MainWindow::~MainWindow() + 207 (mainwindow.cpp:549)
> 19 0x000000010940cd45
> MainWindow::~MainWindow() + 21 (mainwindow.cpp:542)
> 20 org.qt-project.QtCore 0x000000010cba4748
> QObject::event(QEvent*) + 776 (qobject.cpp:4455)
> 21 org.qt-project.QtWidgets 0x000000010b164d26
> QWidget::event(QEvent*) + 3622 (qwidget.cpp:9105)
> 22 org.qt-project.QtWidgets 0x000000010b26c45f
> QMainWindow::event(QEvent*) + 911 (qmainwindow.cpp:1495)
> 23 libKF5XmlGui.5.dylib 0x000000010a81e810
> KMainWindow::event(QEvent*) + 624 (kmainwindow.cpp:829)
> 24 libKF5XmlGui.5.dylib 0x000000010a856398
> KXmlGuiWindow::event(QEvent*) + 24 (kxmlguiwindow.cpp:118)
> 25 org.qt-project.QtWidgets 0x000000010b12653b
> QApplicationPrivate::notify_helper(QObject*, QEvent*) + 251
> (qapplication.cpp:3716)
> 26 org.qt-project.QtWidgets 0x000000010b1298f4
> QApplication::notify(QObject*, QEvent*) + 8212 (qapplication.cpp:3681)
> 27 org.qt-project.QtCore 0x000000010cb7c0db
> QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) + 971
> (qthread_p.h:291)
> 28 org.qt-project.QtCore 0x000000010cb7ba2c
> QCoreApplication::exec() + 412 (qcoreapplication.cpp:1240)
> 29 0x00000001093f3761 main + 10257
> (main.cpp:118)
> 30 libdyld.dylib 0x00007fff8508c5fd start + 1
> ```
>
> When I say crash-on-exit, I mean that the crash occurs after selecting
> the Quit menu item, or closing the main window.
Here's a backtrace obtained in the debugger:
```
* thread #1: tid = 0x3727c3, 0x0000000103c4e886 QtCore`QObject::property(char
const*) const [inlined] QListData::size() const + 4 at qlist.h:105, queue =
'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
frame #0: 0x0000000103c4e886 QtCore`QObject::property(char const*) const
[inlined] QListData::size() const + 4 at qlist.h:105
102 void remove(int i);
103 void remove(int i, int n);
104 void move(int from, int to);
-> 105 inline int size() const { return d->end - d->begin; }
106 inline bool isEmpty() const { return d->end == d->begin; }
107 inline void **at(int i) const { return d->array + d->begin + i; }
108 inline void **begin() const { return d->array + d->begin; }
(lldb) bt
* thread #1: tid = 0x3727c3, 0x0000000103c4e886 QtCore`QObject::property(char
const*) const [inlined] QListData::size() const + 4 at qlist.h:105, queue =
'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
* frame #0: 0x0000000103c4e886 QtCore`QObject::property(char const*) const
[inlined] QListData::size() const + 4 at qlist.h:105
frame #1: 0x0000000103c4e882 QtCore`QObject::property(char const*) const
[inlined] QList<QByteArray>::indexOf(this=0x0000000118b9a1c0,
t=0x0000000118b9a1c0, from=<unavailable>) const at qlist.h:940
frame #2: 0x0000000103c4e882 QtCore`QObject::property(this=<unavailable>,
name=0x000000010af1799a) const + 146 at qobject.cpp:3884
frame #3: 0x000000010ae9e37a
libqcocoa.dylib`QCocoaMenuItem::~QCocoaMenuItem(this=0x00000001069bd9d0) + 58
at qcocoamenuitem.mm:109
frame #4: 0x000000010ae9e52e
libqcocoa.dylib`QCocoaMenuItem::~QCocoaMenuItem() [inlined]
QCocoaMenuItem::~QCocoaMenuItem(this=0x00000001069bd9d0) + 14 at
qcocoamenuitem.mm:106
frame #5: 0x000000010ae9e529
libqcocoa.dylib`QCocoaMenuItem::~QCocoaMenuItem(this=0x00000001069bd9d0) + 9 at
qcocoamenuitem.mm:106
frame #6: 0x00000001022339bd
QtWidgets`QMenu::actionEvent(this=0x00000001069bce00, e=<unavailable>) + 749 at
qmenu.cpp:3224
frame #7: 0x00000001020ff3d0
QtWidgets`QWidget::event(this=0x00000001069bce00, event=0x00007fff5fbfde30) +
1232 at qwidget.cpp:9044
frame #8: 0x0000000102231bdc
QtWidgets`QMenu::event(this=0x00000001069bce00, e=0x00007fff5fbfde30) + 1164 at
qmenu.cpp:2678
frame #9: 0x00000001020c153b
QtWidgets`QApplicationPrivate::notify_helper(this=<unavailable>,
receiver=0x00000001069bce00, e=0x00007fff5fbfde30) + 251 at
qapplication.cpp:3716
frame #10: 0x00000001020c48f4
QtWidgets`QApplication::notify(this=<unavailable>, receiver=<unavailable>,
e=<unavailable>) + 8212 at qapplication.cpp:3681
frame #11: 0x0000000103c1d433
QtCore`QCoreApplication::notifyInternal(this=<unavailable>,
receiver=<unavailable>, event=<unavailable>) + 115 at qcoreapplication.cpp:970
frame #12: 0x00000001020f32ed QtWidgets`QWidget::removeAction(QAction*)
[inlined] QCoreApplication::sendEvent(receiver=<unavailable>,
event=0x00000001037c1480) + 125 at qcoreapplication.h:224
frame #13: 0x00000001020f32ce
QtWidgets`QWidget::removeAction(this=<unavailable>, action=0x0000000106a7eff0)
+ 94 at qwidget.cpp:3317
frame #14: 0x00000001020b7711
QtWidgets`QAction::~QAction(this=0x0000000106a7eff0) + 97 at qaction.cpp:568
frame #15: 0x000000010210816c
QtWidgets`QWidgetAction::~QWidgetAction(this=0x0000000106a7eff0) + 444 at
qwidgetaction.cpp:122
frame #16: 0x0000000101db9d80
libKF5WidgetsAddons.5.dylib`KSelectAction::~KSelectAction() [inlined]
KSelectAction::~KSelectAction(this=0x0000000106a7eff0) + 64 at
kselectaction.cpp:107
frame #17: 0x0000000101db9d49
libKF5WidgetsAddons.5.dylib`KSelectAction::~KSelectAction() [inlined]
KSelectAction::~KSelectAction(this=0x0000000106a7eff0) at kselectaction.cpp:99
frame #18: 0x0000000101db9d49
libKF5WidgetsAddons.5.dylib`KSelectAction::~KSelectAction(this=0x0000000106a7eff0)
+ 9 at kselectaction.cpp:99
frame #19: 0x0000000103c45d75
QtCore`QObjectPrivate::deleteChildren(this=0x0000000106a78e30) + 245 at
qobject.cpp:1946
frame #20: 0x00000001020eeee1
QtWidgets`QWidget::~QWidget(this=0x0000000106a78c80) + 1441 at qwidget.cpp:1658
frame #21: 0x0000000100363e6b kdenlive`Bin::~Bin(this=0x0000000106a78c80) +
1067 at bin.cpp:458
frame #22: 0x0000000100363fce kdenlive`Bin::~Bin() [inlined]
Bin::~Bin(this=0x0000000106a78c80) + 14 at bin.cpp:440
frame #23: 0x0000000100363fc9 kdenlive`Bin::~Bin(this=0x0000000106a78c80) +
9 at bin.cpp:440
frame #24: 0x00000001003e8bed kdenlive`Core::~Core() [inlined]
Core::~Core(this=0x0000000106a6ba60) + 68 at core.cpp:47
frame #25: 0x00000001003e8ba9 kdenlive`Core::~Core() [inlined]
Core::~Core(this=0x0000000106a6ba60) at core.cpp:43
frame #26: 0x00000001003e8ba9 kdenlive`Core::~Core(this=0x0000000106a6ba60)
+ 9 at core.cpp:43
frame #27: 0x00000001003bbb8f
kdenlive`MainWindow::~MainWindow(this=0x0000000106b4df40,
vtt=0x00000001004e1850) + 207 at mainwindow.cpp:614
frame #28: 0x00000001003bbf75 kdenlive`MainWindow::~MainWindow() [inlined]
MainWindow::~MainWindow(this=0x0000000106b4df40) + 12 at mainwindow.cpp:608
frame #29: 0x00000001003bbf69
kdenlive`MainWindow::~MainWindow(this=0x0000000106b4df40) + 9 at
mainwindow.cpp:608
frame #30: 0x0000000103c46748 QtCore`QObject::event(QEvent*) [inlined]
qDeleteInEventHandler(o=0x0000000106b4df40) + 14 at qobject.cpp:4455
frame #31: 0x0000000103c4673a
QtCore`QObject::event(this=0x0000000106b4df40, e=<unavailable>) + 762 at
qobject.cpp:1230
frame #32: 0x00000001020ffd26
QtWidgets`QWidget::event(this=0x0000000106b4df40, event=0x00000001236a90d0) +
3622 at qwidget.cpp:9105
frame #33: 0x000000010220745f
QtWidgets`QMainWindow::event(this=0x0000000106b4df40, event=0x00000001236a90d0)
+ 911 at qmainwindow.cpp:1495
frame #34: 0x0000000101925810
libKF5XmlGui.5.dylib`KMainWindow::event(this=0x0000000106b4df40,
ev=0x00000001236a90d0) + 624 at kmainwindow.cpp:829
frame #35: 0x000000010195d398
libKF5XmlGui.5.dylib`KXmlGuiWindow::event(this=0x0000000106b4df40,
ev=0x00000001236a90d0) + 24 at kxmlguiwindow.cpp:118
frame #36: 0x00000001020c153b
QtWidgets`QApplicationPrivate::notify_helper(this=<unavailable>,
receiver=0x0000000106b4df40, e=0x00000001236a90d0) + 251 at
qapplication.cpp:3716
frame #37: 0x00000001020c48f4
QtWidgets`QApplication::notify(this=<unavailable>, receiver=<unavailable>,
e=<unavailable>) + 8212 at qapplication.cpp:3681
frame #38: 0x0000000103c1e0db
QtCore`QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*)
[inlined] QCoreApplication::notifyInternal(this=<unavailable>,
receiver=<unavailable>, event=<unavailable>) + 95 at qcoreapplication.cpp:970
frame #39: 0x0000000103c1e07c
QtCore`QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*)
[inlined] QCoreApplication::sendEvent(receiver=<unavailable>,
event=0x00000001236a90d0) + 28 at qcoreapplication.h:224
frame #40: 0x0000000103c1e060
QtCore`QCoreApplicationPrivate::sendPostedEvents(receiver=0x0000000000000000,
event_type=0, data=0x0000000106a00e70) + 848 at qcoreapplication.cpp:1598
frame #41: 0x0000000103c1da2c QtCore`QCoreApplication::exec() + 412 at
qcoreapplication.cpp:1240
frame #42: 0x00000001003a13b1 kdenlive`main(argc=1, argv=<unavailable>) +
9841 at main.cpp:126
frame #43: 0x00007fff8508c5fd libdyld.dylib`start + 1
frame #44: 0x00007fff8508c5fd libdyld.dylib`start + 1
```
> On Jan. 12, 2016, 10:49 p.m., David Faure wrote:
> > src/kselectaction.cpp, line 101
> > <https://git.reviewboard.kde.org/r/126725/diff/1/?file=430463#file430463line101>
> >
> > This seems unnecessary and wasteful (it sends an ActionChanged event).
> > You're not deleting the menu right now anyway, you're using deleteLater. So
> > the action will be gone before the menu is deleted, therefore the action
> > will never have a dangling pointer to the menu.
>
> René J.V. Bertin wrote:
> It's almost impossible to debug this kind of situation because an
> interactive debugging session will alter the event flow. It does look like
> we're dealing only with Qt events here, no pending native events that get
> delivered to ObjC objects.
> Doesn't the menu have its parent set to the action (KSelectAction), and
> if so, will that relationship be broken when the action gets deleted? Because
> if not, it's the menu that could have a dangling pointer to the action, no?
> Also, remember that using deleteLater isn't required to prevent the
> systematic crash-on-exit. I suppose I could try to see if deleting the d-ptr
> last is the most important change here.
So...
- `delete menu() ; delete d_ptr;` crashes just as hard as `delete d_ptr ;
delete menu();`
- a `delete menu();` doesn't crash after a preceding `setMenu(Q_NULLPTR);`
- `if(m) m->deleteLater();` *without* `setMenu(Q_NULLPTR);` _doesn't_ crash (at
least not all the time).
I think that really means that the safest workaround will be the implementation
I submitted. We can of course try to use either setMenu+delete or else
deleteLater on its own and go from there if a sufficiently repeatable crasher
represents itself.
- René J.V.
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/126725/#review90980
-----------------------------------------------------------
On Jan. 12, 2016, 2:14 p.m., René J.V. Bertin wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/126725/
> -----------------------------------------------------------
>
> (Updated Jan. 12, 2016, 2:14 p.m.)
>
>
> Review request for KDE Frameworks and Christoph Feck.
>
>
> Repository: kwidgetsaddons
>
>
> Description
> -------
>
> I was seeing a systematic crash on exitting kdenlive5, on OS X deep under the
> `delete menu()` instruction in `KSelectAction::~KSelectAction`. The backtrace
> suggested this might be due to a pending event (or an event due to the menu
> deletion) being delivered post-mortem to an instance of a QMenu related class.
>
> My fix is based on 3 principles:
> 1) release the "foreign" member instance (`menu()`) before releasing the own
> d-ptr
> 2) Remove the QMenu instance from ourselves before deleting it to have one
> less potential dangling reference to it
> 3) QMenu is a QObject descendent that corresponds to a UI element: on OS X it
> is safer to dispose these through `deleteLater()` rather than directly.
>
>
> Diffs
> -----
>
> src/kselectaction.cpp 1381099
>
> Diff: https://git.reviewboard.kde.org/r/126725/diff/
>
>
> Testing
> -------
>
> On OS X 10.9.5, Qt 5.5.1 and KF5 Frameworks 5.16.0, built for installation
> under /opt/local .
>
> It seems that points 1) and 2) above already solve the crash issue in
> kdenlive on OS X, but the general principle stands so I suggest keeping 3) in
> library code like this.
>
>
> Thanks,
>
> René J.V. Bertin
>
>
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