Core dump with PyQt4

Question

I am starting with PyQt4 and am facing a coredump when using QGraphicsScene/View in the easiest of the examples:

#!/usr/bin/python

import sys
from PyQt4.QtC         


        

Answer 1

The GTK errors are probably unrelated to the segfault. I'm using KDE (and therefore not the gtk theme), so I don't see any GTK errors, but i do get a segfault.

The segfault happens in the destructor of the QGraphicsScene:

#0  0x00007ffff6f09037 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff6f0c698 in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007ffff5b465c2 in qt_message_output(QtMsgType, char const*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#3  0x00007ffff5b46938 in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#4  0x00007ffff5b46ac4 in qFatal(char const*, ...) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#5  0x00007ffff389231e in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#6  0x00007ffff3893401 in QPixmap::QPixmap() () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#7  0x00007fffea0a8c86 in Oxygen::Helper::Helper(QByteArray const&) () from /usr/lib/liboxygenstyle.so.4
#8  0x00007fffea3450e0 in ?? () from /usr/lib/kde4/plugins/styles/oxygen.so
#9  0x00007fffea32f757 in ?? () from /usr/lib/kde4/plugins/styles/oxygen.so
#10 0x00007fffea33c7bc in ?? () from /usr/lib/kde4/plugins/styles/oxygen.so
#11 0x00007ffff3ab64e6 in QStyleFactory::create(QString const&) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#12 0x00007ffff37c74cf in QApplication::style() () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#13 0x00007ffff37fe488 in QWidget::isActiveWindow() const () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#14 0x00007ffff3dd5ccc in QGraphicsView::setScene(QGraphicsScene*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#15 0x00007ffff3da47d1 in QGraphicsScene::~QGraphicsScene() () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4
#16 0x00007ffff46b6bb9 in ?? () from /usr/lib/python2.7/dist-packages/PyQt4/QtGui.so
#17 0x00007ffff46b4ad6 in ?? () from /usr/lib/python2.7/dist-packages/PyQt4/QtGui.so
#18 0x00007ffff4c6115e in ?? () from /usr/lib/python2.7/dist-packages/sip.so
#19 0x00007ffff4c62aa9 in ?? () from /usr/lib/python2.7/dist-packages/sip.so
#20 0x00000000004af4f0 in ?? ()
#21 0x00000000004dbbc7 in ?? ()
#22 0x00007ffff4c6058b in ?? () from /usr/lib/python2.7/dist-packages/sip.so
#23 0x00007ffff4c62a22 in ?? () from /usr/lib/python2.7/dist-packages/sip.so
#24 0x00007ffff4c62ab1 in ?? () from /usr/lib/python2.7/dist-packages/sip.so
#25 0x00000000004af4f0 in ?? ()
#26 0x00000000004b8bca in ?? ()
#27 0x00000000004a4460 in PyDict_SetItem ()
#28 0x00000000004a46d7 in _PyModule_Clear ()
#29 0x0000000000509514 in PyImport_Cleanup ()
#30 0x0000000000423bca in Py_Finalize ()
#31 0x0000000000424470 in Py_Exit ()
#32 0x00000000004245ac in ?? ()
#33 0x000000000042254e in PyErr_PrintEx ()
#34 0x0000000000465e0d in PyRun_SimpleFileExFlags ()
#35 0x0000000000466b78 in Py_Main ()
#36 0x00007ffff6ef3ea5 in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
#37 0x00000000004e0d95 in _start ()

Making grview the parent of scene should fix this problem:

#!/usr/bin/python

import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *

app = QApplication(sys.argv)

grview = QGraphicsView()
scene = QGraphicsScene(grview)

grview.setScene(scene)

grview.show()

sys.exit(app.exec_())

QObjects constructed without parent are owned by PyQt and not by Qt, this error is probably a result of the destructor being called twice when exiting.