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List: kde-frameworks-devel
Subject: Re: Review Request 126725: prevent crash-on-exit in KSelectAction::~KSelectAction
From: René J.V. Bertin <rjvbertin () gmail ! com>
Date: 2016-01-13 18:49:54
Message-ID: 20160113184954.23702.60099 () mimi ! kde ! org
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> 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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This is an automatically generated e-mail. To reply, visit:
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<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <p style="margin-top: 0;">On January 12th, 2016, 10:49 p.m. CET, <b>David \
Faure</b> wrote:</p> <blockquote style="margin-left: 1em; border-left: 2px solid \
#d0d0d0; padding-left: 10px;"> <pre style="white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">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...).</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">Is the action being \
destroyed by clicking into a submenu of the action? Otherwise I don't get the \
relation with the fix.</p></pre> </blockquote>
<p>On January 13th, 2016, 2:20 a.m. CET, <b>René J.V. Bertin</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">A \
CrashReporter backtrace I still had logged:</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;"><div class="codehilite" \
style="background: #f8f8f8"><pre style="line-height: 125%">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 </pre></div>
</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">When I say crash-on-exit, I mean that the crash occurs \
after selecting the Quit menu item, or closing the main window.</p></pre> \
</blockquote>
</blockquote>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">Here's a backtrace obtained in the debugger:</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;"><div \
class="codehilite" style="background: #f8f8f8"><pre style="line-height: 125%">* \
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
</pre></div>
</p></pre>
<br />
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <p style="margin-top: 0;">On January 12th, 2016, 10:49 p.m. CET, <b>David \
Faure</b> wrote:</p> <blockquote style="margin-left: 1em; border-left: 2px solid \
#d0d0d0; padding-left: 10px;">
<table width="100%" border="0" bgcolor="white" style="border: 1px solid #C0C0C0; \
border-collapse: collapse; margin: 2px padding: 2px;"> <thead>
<tr>
<th colspan="4" bgcolor="#F0F0F0" style="border-bottom: 1px solid #C0C0C0; \
font-size: 9pt; padding: 4px 8px; text-align: left;"> <a \
href="https://git.reviewboard.kde.org/r/126725/diff/1/?file=430463#file430463line101" \
style="color: black; font-weight: bold; text-decoration: \
underline;">src/kselectaction.cpp</a> <span style="font-weight: normal;">
(Diff revision 1)
</span>
</th>
</tr>
</thead>
<tbody style="background-color: #e4d9cb; padding: 4px 8px; text-align: center;">
<tr>
<td colspan="4"><pre style="font-size: 8pt; line-height: 140%; margin: 0; \
">KSelectAction::KSelectAction(KSelectActionPrivate &dd, QObject \
*parent)</pre></td>
</tr>
</tbody>
<tbody>
<tr>
<th bgcolor="#b1ebb0" style="border-right: 1px solid #C0C0C0;" \
align="right"><font size="2"></font></th> <td bgcolor="#c5ffc4" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; "></pre></td> <th \
bgcolor="#b1ebb0" style="border-left: 1px solid #C0C0C0; border-right: 1px solid \
#C0C0C0;" align="right"><font size="2">101</font></th> <td bgcolor="#c5ffc4" \
width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "> <span \
class="n">setMenu</span><span class="p">(</span><span class="n">Q_NULLPTR</span><span \
class="p">);</span></pre></td> </tr>
</tbody>
</table>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">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.</p></pre> </blockquote>
<p>On January 13th, 2016, 2:20 a.m. CET, <b>René J.V. Bertin</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">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.</p></pre> \
</blockquote>
</blockquote>
<pre style="margin-left: 1em; white-space: pre-wrap; white-space: -moz-pre-wrap; \
white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">So...</p> <ul style="padding: 0;text-rendering: inherit;margin: 0 0 0 \
1em;line-height: inherit;white-space: normal;"> <li style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: normal;"><code \
style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: normal;margin: \
0;line-height: inherit;">delete menu() ; delete d_ptr;</code> crashes just as hard as \
<code style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: \
normal;margin: 0;line-height: inherit;">delete d_ptr ; delete menu();</code></li> <li \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
normal;">a <code style="text-rendering: inherit;color: #4444cc;padding: \
0;white-space: normal;margin: 0;line-height: inherit;">delete menu();</code> doesn't \
crash after a preceding <code style="text-rendering: inherit;color: #4444cc;padding: \
0;white-space: normal;margin: 0;line-height: \
inherit;">setMenu(Q_NULLPTR);</code></li> <li style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: normal;"><code \
style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: normal;margin: \
0;line-height: inherit;">if(m) m->deleteLater();</code> <em style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
normal;">without</em> <code style="text-rendering: inherit;color: #4444cc;padding: \
0;white-space: normal;margin: 0;line-height: inherit;">setMenu(Q_NULLPTR);</code> <em \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
normal;">doesn't</em> crash (at least not all the time).</li> </ul>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">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.</p></pre> <br />
<p>- René J.V.</p>
<br />
<p>On January 12th, 2016, 2:14 p.m. CET, René J.V. Bertin wrote:</p>
<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: \
1px #888a85 solid; border-radius: 6px; -moz-border-radius: 6px; \
-webkit-border-radius: 6px;"> <tr>
<td>
<div>Review request for KDE Frameworks and Christoph Feck.</div>
<div>By René J.V. Bertin.</div>
<p style="color: grey;"><i>Updated Jan. 12, 2016, 2:14 p.m.</i></p>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt;">Repository: </b>
kwidgetsaddons
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">I was seeing a systematic crash on exitting kdenlive5, \
on OS X deep under the <code style="text-rendering: inherit;color: #4444cc;padding: \
0;white-space: normal;margin: 0;line-height: inherit;">delete menu()</code> \
instruction in <code style="text-rendering: inherit;color: #4444cc;padding: \
0;white-space: normal;margin: 0;line-height: \
inherit;">KSelectAction::~KSelectAction</code>. 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.</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">My \
fix is based on 3 principles: 1) release the "foreign" member instance (<code \
style="text-rendering: inherit;color: #4444cc;padding: 0;white-space: normal;margin: \
0;line-height: inherit;">menu()</code>) 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 <code style="text-rendering: inherit;color: \
#4444cc;padding: 0;white-space: normal;margin: 0;line-height: \
inherit;">deleteLater()</code> rather than directly.</p></pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">On OS X 10.9.5, Qt 5.5.1 and KF5 Frameworks 5.16.0, \
built for installation under /opt/local .</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">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.</p></pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>src/kselectaction.cpp <span style="color: grey">(1381099)</span></li>
</ul>
<p><a href="https://git.reviewboard.kde.org/r/126725/diff/" style="margin-left: \
3em;">View Diff</a></p>
</td>
</tr>
</table>
</div>
</body>
</html>
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