[PyQt] QtWebEngineWidgets crasher
Kovid Goyal
kovid at kovidgoyal.net
Fri Mar 20 01:51:23 GMT 2015
On Thu, Mar 19, 2015 at 04:55:50PM +0000, Baz Walter wrote:
> The description of the problem in your linked thread closely matches my own
> situation. I ported a working, reliable PyQt4 application to PyQt5 without
> any difficulties. It was only when I tried switching from QWebKit to
> QWebEngine that the issue showed up. It took me quite a while to realize
> that it was *only* the QWebEngine import that made the difference.
Since I can produce it with just QMainWindow I doubt it has anything
to do with WebEngine. It is likely that importing it simply changes the
order of object cleanup during interpreter shutdown, which triggers the
crash.
>
> It's funny that you suggest making the main window an attribute of the
> application object, because my application already does exactly that! Like
> you say, it's relatively easy to fix the simple cases, but more complex
> applications are generally much harder to deal with (and there's no
> guarantee that potential fixes will last).
For my application (calibre) I have found that the crashes only occur
during interpreter shutdown, so it is not too critical for me, as it
does not interfere with any actual functionality. So far, I have just
been ignoring it, in the hopes it someone else would tackle fixing it :)
I think the next step is to compile Qt from source and
try to pin down the crash in the xcb plugin. However, I am totally
swamped at the moment, so it will be some time before I can do that.
Kovid.
>
> Your suspicions about QXcbEventReader and QPA plugins seem to match what I'm
> seeing. Here's what I get from valgrind:
>
> $ valgrind --tool=memcheck --suppressions=valgrind-python.supp python -E -tt
> ./test_webeng.py
> ==3106== Memcheck, a memory error detector
> ==3106== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
> ==3106== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
> ==3106== Command: python -E -tt ./test_webeng.py
> ==3106==
> ==3109== Warning: invalid file descriptor 1024 in syscall close()
> ==3109== Warning: invalid file descriptor 1025 in syscall close()
> ==3109== Warning: invalid file descriptor 1026 in syscall close()
> ==3109== Warning: invalid file descriptor 1027 in syscall close()
> ==3109== Use --log-fd=<number> to select an alternative log fd.
> ==3109== Warning: invalid file descriptor 1028 in syscall close()
> ==3109== Warning: invalid file descriptor 1029 in syscall close()
> ==3109== Warning: invalid file descriptor 1030 in syscall close()
> ==3106== Conditional jump or move depends on uninitialised value(s)
> ==3106== at 0xF031A2F: ??? (in /usr/lib/libnvidia-glcore.so.304.125)
> ==3106== by 0x2: ???
> ==3106== by 0xFFEFFDAEF: ???
> ==3106== by 0x1F: ???
> ==3106== by 0xFFEFFDB3F: ???
> ==3106== by 0xFFEFFDB3F: ???
> ==3106== by 0x15B89BFF: ???
> ==3106== by 0x100AE67F: ???
> ==3106== by 0xC1D00190: ???
> ==3106== by 0xC1D00190: ???
> ==3106== by 0xF0322CB: ??? (in /usr/lib/libnvidia-glcore.so.304.125)
> ==3106==
> ==3106== Syscall param writev(vector[...]) points to uninitialised byte(s)
> ==3106== at 0x55CBBDD: ??? (in /usr/lib/libc-2.21.so)
> ==3106== by 0x104E8CCA: ??? (in /usr/lib/libxcb.so.1.1.0)
> ==3106== by 0x104E90C0: ??? (in /usr/lib/libxcb.so.1.1.0)
> ==3106== by 0x104E97E6: ??? (in /usr/lib/libxcb.so.1.1.0)
> ==3106== by 0x104E99B3: xcb_flush (in /usr/lib/libxcb.so.1.1.0)
> ==3106== by 0x11BAD7F9: QXcbWindow::hide() (qxcbwindow.cpp:793)
> ==3106== by 0xC941CA5: QWindow::setVisible(bool) (qwindow.cpp:507)
> ==3106== by 0xC34361E: QWidgetPrivate::hide_sys() (qwidget.cpp:7976)
> ==3106== by 0xC349913: QWidgetPrivate::hide_helper() (qwidget.cpp:7908)
> ==3106== by 0xC34D8EF: QWidget::setVisible(bool) (qwidget.cpp:8121)
> ==3106== by 0xBD04CD7: sipQWidget::setVisible(bool)
> (sipQtWidgetsQWidget.cpp:1139)
> ==3106== by 0xC349B93:
> QWidgetPrivate::close_helper(QWidgetPrivate::CloseMode) (qwidget.cpp:8250)
> ==3106== Address 0x11a3e571 is 4,529 bytes inside a block of size 21,144
> alloc'd
> ==3106== at 0x4C2C080: calloc (in
> /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==3106== by 0x104E866B: xcb_connect_to_fd (in /usr/lib/libxcb.so.1.1.0)
> ==3106== by 0x104EC120: xcb_connect_to_display_with_auth_info (in
> /usr/lib/libxcb.so.1.1.0)
> ==3106== by 0xD3464B9: _XConnectXCB (in /usr/lib/libX11.so.6.3.0)
> ==3106== by 0xD3371E1: XOpenDisplay (in /usr/lib/libX11.so.6.3.0)
> ==3106== by 0x11B9CE26:
> QXcbConnection::QXcbConnection(QXcbNativeInterface*, bool, char const*)
> (qxcbconnection.cpp:332)
> ==3106== by 0x11BA08A3: QXcbIntegration::QXcbIntegration(QStringList
> const&, int&, char**) (qxcbintegration.cpp:174)
> ==3106== by 0x11BB54AA: QXcbIntegrationPlugin::create(QString const&,
> QStringList const&, int&, char**) (qxcbmain.cpp:50)
> ==3106== by 0xC928011: loadIntegration
> (qplatformintegrationfactory.cpp:56)
> ==3106== by 0xC928011: QPlatformIntegrationFactory::create(QString
> const&, QStringList const&, int&, char**, QString const&)
> (qplatformintegrationfactory.cpp:73)
> ==3106== by 0xC933BCA: init_platform (qguiapplication.cpp:1010)
> ==3106== by 0xC933BCA:
> QGuiApplicationPrivate::createPlatformIntegration()
> (qguiapplication.cpp:1165)
> ==3106== by 0xC934A1C: QGuiApplicationPrivate::createEventDispatcher()
> (qguiapplication.cpp:1182)
> ==3106== by 0x734CDCE: QCoreApplication::init()
> (qcoreapplication.cpp:730)
> ==3106==
> ==3106== Thread 2 QXcbEventReader:
> ==3106== Jump to the invalid address stated on the next line
> ==3106== at 0x11B9E399: ???
> ==3106== by 0x15258F0F: ???
> ==3106== by 0x11A4B4DF: ???
> ==3106== by 0x15258F4F: ???
> ==3106== by 0x11A4B8EF: ???
> ==3106== by 0xFFEFFFA2E: ???
> ==3106== by 0x715D55D: QThreadPrivate::start(void*)
> (qthread_unix.cpp:337)
> ==3106== by 0x741DE1F: ??? (in /usr/lib/libQt5Core.so.5.4.1)
> ==3106== by 0x52D5313: start_thread (in /usr/lib/libpthread-2.21.so)
> ==3106== Address 0x11b9e399 is not stack'd, malloc'd or (recently) free'd
> ==3106==
> ==3106==
> ==3106== Process terminating with default action of signal 11 (SIGSEGV)
> ==3106== Access not within mapped region at address 0x11B9E399
> ==3106== at 0x11B9E399: ???
> ==3106== by 0x15258F0F: ???
> ==3106== by 0x11A4B4DF: ???
> ==3106== by 0x15258F4F: ???
> ==3106== by 0x11A4B8EF: ???
> ==3106== by 0xFFEFFFA2E: ???
> ==3106== by 0x715D55D: QThreadPrivate::start(void*)
> (qthread_unix.cpp:337)
> ==3106== by 0x741DE1F: ??? (in /usr/lib/libQt5Core.so.5.4.1)
> ==3106== by 0x52D5313: start_thread (in /usr/lib/libpthread-2.21.so)
> ==3106== If you believe this happened as a result of a stack
> ==3106== overflow in your program's main thread (unlikely but
> ==3106== possible), you can try to increase the size of the
> ==3106== main thread stack using the --main-stacksize= flag.
> ==3106== The main thread stack size used in this run was 8388608.
> ==3106==
> ==3106== HEAP SUMMARY:
> ==3106== in use at exit: 6,585,960 bytes in 28,817 blocks
> ==3106== total heap usage: 94,842 allocs, 66,025 frees, 18,983,597 bytes
> allocated
> ==3106==
> ==3106== LEAK SUMMARY:
> ==3106== definitely lost: 262,674 bytes in 10 blocks
> ==3106== indirectly lost: 0 bytes in 0 blocks
> ==3106== possibly lost: 714,229 bytes in 2,452 blocks
> ==3106== still reachable: 5,609,057 bytes in 26,355 blocks
> ==3106== suppressed: 0 bytes in 0 blocks
> ==3106== Rerun with --leak-check=full to see details of leaked memory
> ==3106==
> ==3106== For counts of detected and suppressed errors, rerun with: -v
> ==3106== Use --track-origins=yes to see where uninitialised values come from
> ==3106== ERROR SUMMARY: 3 errors from 3 contexts (suppressed: 0 from 0)
> Killed
>
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--
_____________________________________
Dr. Kovid Goyal
http://www.kovidgoyal.net
http://calibre-ebook.com
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