[PyQt] Bug report: crash when using QSytemTrayIcon

[z]

2010/3/5 Phil Thompson <phil at riverbankcomputing.com>

> On Fri, 5 Mar 2010 00:35:21 +0100, Kiwi <spiky.kiwi at gmail.com> 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.
>
>
I found another problem, which i think is also caused by delete order:
######
app = QApplication(sys.argv)

pushButton = QPushButton()
gProxyButton =  QGraphicsProxyWidget()
gProxyButton.setWidget(pushButton)

view = QGraphicsView()
view.show()

app.exec_()
sys.exit()
######
on exit this program will crash with segfault.
but if the proxy widget will be added to the scene, or explicitly deleted
afer app.exec_(), all will be fine

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.
>

So can the problem i described also be fixed the same way, as the OP says
(i.e. make QGraphicsProxyWidget deleted before QApplication) ?


> Phil
> _______________________________________________
> PyQt mailing list    PyQt at riverbankcomputing.com
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>
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