[PyQt] QSystemTrayIcon still crashed app (PyQt4 4.9.1)

[Phil Thompson]

On Mon, 28 May 2012 11:39:35 +0800, zw g <pekingmaster at gmail.com> wrote:
> Hi Phil,
> 
> 
> 
> It seems the latest version of PyQt4 still has this bug.
> My installation:
> 
> *  Python 2.7.3
> *  PyQt4 4.9.1
> *  SIP 4.13.1
> *  Mac OS X 10.7.4
> 
> I don't know if it is the same as the quoted below, but very similar,
and
> if i delete the instance of
> QSystemTrayIcon before exiting, then everything is fine.

I don't think this, or the earlier report, is a bug. As I said in my
original explanation the problem is probably the random order in which C++
instances get destroyed. Explicitly del'ing a object, or giving it an
appropriate parent is the best way to deal with it.

Phil

> Quote below:
> 
> ======================================================
> 
> On Fri, 5 Mar 2010 00:35:21 +0100, Kiwi <spiky.kiwi at gmail.com
> <http://www.riverbankcomputing.com/mailman/listinfo/pyqt>> wrote:
>>* Hi,*>* I'm totally new to PyQt programming.*>* While I was writing a
>>very simple app for the system tray I think I found*a
>>* bug.*>* Here is a simple testcase:*>* *>* # -*- coding: utf-8 -*-*>*
>>import sys*>* from PyQt4 import QtGui, QtCore*>* *>* app =
>>QtGui.QApplication(sys.argv)*>* *>* tray = QtGui.QSystemTrayIcon()*>*
*>*
>>def a(): pass*>* def b(): pass*>* def c(): pass*>* def d(): pass*>* def
>>e(): pass*>* def f(): pass*>* def g(): pass*>* def h(): pass*>* def i():
>>pass*>* def j(): pass*>* def k(): pass*>* *>* cm = QtGui.QMenu()*>*
>>cm.addAction("Exit",QtGui.QApplication.quit)*>* *>*
>>tray.setContextMenu(cm)*>* *>* tray.show()*>* sys.exit(app.exec_())*>*
*>*
>>*>* note that the "defs" are needed to make the crash happen.*>* FYI,
>>running linux on x86_64*>* versions:*>* qt: 4.6.2*>* pyqt: 4 4.7*>* sip:
>>4.10*>* python: 2.6.4*>* gcc: 4.4.3*>* libX11 1.3.3*>* *>* here is the
>>backtrace:*>* (gdb) run*>* Starting program: /usr/bin/python2.6
>>crash.py*>* [Thread debugging using libthread_db enabled]*>*
>>QSystemTrayIcon::setVisible: No Icon set*>* *>* Program received signal
>>SIGSEGV, Segmentation fault.*>* XFreeColormap (dpy=0x0, cmap=16777218)
at
>>FreeCmap.c:41*>* 41      FreeCmap.c: No such file or directory.*>*      

>>in FreeCmap.c*>* (gdb) bt*>* #0  XFreeColormap (dpy=0x0, cmap=16777218)
at
>>FreeCmap.c:41*>* #1  0x00007ffff5f1b558 in ~QSystemTrayIconSys
>>(this=0x9c3070,*>* __in_chrg=<value optimized out>) at
>>util/qsystemtrayicon_x11.cpp:213*>* #2  0x00007ffff5f19ff4 in
>>QSystemTrayIconPrivate::remove_sys*>* (this=0x9bc310) at
>>util/qsystemtrayicon_x11.cpp:352*>* #3  0x00007ffff5f0637f in
>>~QSystemTrayIcon (this=0x8c6590,*>* __in_chrg=<value optimized out>) at
>>util/qsystemtrayicon.cpp:152*>* #4  0x00007ffff65f46f2 in
>>~sipQSystemTrayIcon (this=0x8c6590,*>* __in_chrg=<value optimized out>)
at
>>sipQtGuiQSystemTrayIcon.cpp:137*>* #5  0x00007ffff65f347c in
>>release_QSystemTrayIcon (sipCppV=0x8c6590,*>* sipState=<value optimized
>>out>) at sipQtGuiQSystemTrayIcon.cpp:752*>* #6  0x00007ffff219c289 in
>>sipWrapper_dealloc (self=0x0) at siplib.c:9675*>* #7  0x00007ffff7adc0e5
>>in subtype_dealloc (self=0x7ffff7f1caf0) at*>*
>>Objects/typeobject.c:1019*>* #8  0x00007ffff7aba0cf in insertdict
>>(mp=0x63cf60, key=0x7ffff7f08870,*>* hash=2314047222216391292,
>>value=0x7ffff7dab5d0) at*>* Objects/dictobject.c:459*>* #9 
>>0x00007ffff7abcb15 in PyDict_SetItem (op=0x63cf60,*>*
key=0x7ffff7f08870,
>>value=0x7ffff7dab5d0) at Objects/dictobject.c:701*>* #10
>>0x00007ffff7abe48d in _PyModule_Clear (m=<value optimized out>) at*>*
>>Objects/moduleobject.c:138*>* #11 0x00007ffff7b2ac4f in PyImport_Cleanup
>>() at Python/import.c:439*>* #12 0x00007ffff7b33c46 in Py_Finalize () at
>>Python/pythonrun.c:434*>* #13 0x00007ffff7b33d58 in Py_Exit (sts=0) at
>>Python/pythonrun.c:1714*>* #14 0x00007ffff7b33e87 in handle_system_exit
()
>>at*Python/pythonrun.c:1116
>>* #15 0x00007ffff7b340cd in PyErr_PrintEx (set_sys_last_vars=1) at*>*
>>Python/pythonrun.c:1126*>* #16 0x00007ffff7b345a6 in
>>PyRun_SimpleFileExFlags (fp=0x7fffffffe578,*>* filename=0x7fffffffe578
>>"crash.py", closeit=1, flags=0x7fffffffe0d0)*>* at
>>Python/pythonrun.c:935*>* #17 0x00007ffff7b40721 in Py_Main
>>(argc=-134926176, argv=<value*>* optimized out>) at
Modules/main.c:599*>*
>>#18 0x00007ffff74ebbbd in __libc_start_main (main=<value optimized*>*
>>out>, argc=<value optimized out>, ubp_av=<value optimized out>,*>*
>>init=<value optimized out>,*>*     fini=<value optimized out>,
>>rtld_fini=<value optimized out>,*>* stack_end=0x7fffffffe1e8) at
>>libc-start.c:220*>* #19 0x00000000004006b*>* (gdb) f 6*>* #6 
>>0x00007ffff219c289 in sipWrapper_dealloc (self=0x0) at siplib.c:9675*>*
>>9675        forgetObject((sipSimpleWrapper *)self);*>* (gdb) f 5*>* #5 
>>0x00007ffff65f347c in release_QSystemTrayIcon (sipCppV=0x8c6590,*>*
>>sipState=<value optimized out>) at sipQtGuiQSystemTrayIcon.cpp:752*>*
>>warning: Source file is more recent than executable.*>* 752            
>>delete reinterpret_cast<QSystemTrayIcon *>(sipCppV);*>* Current
language: 
>>auto*>* The current source language is "auto; currently c++".*>* (gdb) f
>>4*>* #4  0x00007ffff65f46f2 in ~sipQSystemTrayIcon (this=0x8c6590,*>*
>>__in_chrg=<value optimized out>) at sipQtGuiQSystemTrayIcon.cpp:137*>*
137
>>   }*
> Crashes on exit like this are caused by Qt objects being deleted in the
> "wrong" order. Unfortunately PyQt has (almost) no control over that
order.
> By adding those dummy functions you are altering the order in which
things
> get garbage collected. It doesn't happen with C++ applications because
the
> objects don't get deleted.
> 
> The workaround is to experiment with explicitly deleting objects after
> exec_() returns but before sys.exit() is called. In this case "del tray"
> seems to avoid the crash.
> 
> That said, PyQt does have a mechanism for making sure certain objects
get
> deleted before the QApplication does - and it seems that QSystemTrayIcon
> should also be handled that way. The change will be in tonight's
snapshot.
> 
> Phil
> 
> ======================================================
> 
> 
> 
> In my code ,after a long time debugging, i just found if i commented out
> the following code:
> 
> self.trayNotifier =
> QtGui.QSystemTrayIcon(QtGui.QIcon('images/trayIcon.png'))
> self.trayNotifier.show()
> 
> Then no crash on exit.
> Otherwise, every time i quit my app, crashing windows pop up with the
> following information leave in terminal:
> 
> Segmentation fault: 11
> 
> And the crashing information inside the pop-up window is attached.
> 
> 
> 
> Gui