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Thread: Crash somewhere under sendPostedEvents(), Network related

  1. 7th June 2012, 15:45 #1
    Vinny
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    Default Crash somewhere under sendPostedEvents(), Network related

    Hi all,

    I'm currently working on an application that for historical reasons embeds a simple web server (based on QTcpServer) and a bunch of QWebViews. So yes, all of these are running in different threads of the main application.
    Since some time now we're trying to nail down a crash bug which seems to be thread related. On some computers (mainly WinXP platforms) it seems to happen all the time while on others (like WinSeven) it can be tricky and time-consuming to reproduce.

    The stack is not much from a help, though the main common point is the sendPostedEvents() function, and the crash itself which happens always in a strcmp() call. The rest of the stack may change from one crash to the other. Here is an example :
    Qt Code: 
    1. 0	strcmp	C:\Windows\syswow64\msvcrt.dll	0	0x75e68c19	
    2. 1	??		0	0x17088290	
    3. 2	WebCore::setUpIterator(WebCore::TextBreakIterator&, QTextBoundaryFinder::BoundaryType, wchar_t const*, int)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb646e50	
    4. 3	WebCore::characterBreakIterator(wchar_t const*, int)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb64702a	
    5. 4	WebCore::String::numCharactersInGraphemeClusters(unsigned int) const	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb53ee9d	
    6. 5	WebCore::InputElement::sanitizeUserInputValue(WebCore::InputElement const*, WebCore::String const&, int)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb348028	
    7. 6	WebCore::InputElement::sanitizeValue(WebCore::InputElement const*, WebCore::String const&)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb347f00	
    8. 7	WebCore::HTMLInputElement::sanitizeValue(WebCore::String const&) const	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb427b3a	
    9. 8	WebCore::HTMLInputElement::setValue(WebCore::String const&, bool)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb425012	
    10. 9	WebCore::setJSHTMLInputElementValue(JSC::ExecState*, JSC::JSObject*, JSC::JSValue)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb1a3af1	
    11. 10	bool JSC::lookupPut<WebCore::JSHTMLInputElement>(JSC::ExecState*, JSC::Identifier const&, JSC::JSValue, JSC::HashTable const*, WebCore::JSHTMLInputElement*)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb927041	
    12. 11	void JSC::lookupPut<WebCore::JSHTMLInputElement, WebCore::JSHTMLElement>(JSC::ExecState*, JSC::Identifier const&, JSC::JSValue, JSC::HashTable const*, WebCore::JSHTMLInputElement*, JSC::PutPropertySlot&)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb927075	
    13. 12	WebCore::JSHTMLInputElement::put(JSC::ExecState*, JSC::Identifier const&, JSC::JSValue, JSC::PutPropertySlot&)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb1a2e33	
    14. 13	JSC::JSValue::put(JSC::ExecState*, JSC::Identifier const&, JSC::JSValue, JSC::PutPropertySlot&)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb917af3	
    15. 14	cti_op_put_by_id	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb852c53	
    16. 15	??		0	0x18073a4d	
    17. 16	JSC::JITCode::execute(JSC::RegisterFile*, JSC::ExecState*, JSC::JSGlobalData*, JSC::JSValue*)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb916ef1	
    18. 17	JSC::Interpreter::execute(JSC::ProgramExecutable*, JSC::ExecState*, JSC::ScopeChainNode*, JSC::JSObject*, JSC::JSValue*)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb802f9a	
    19. 18	JSC::evaluate(JSC::ExecState*, JSC::ScopeChain&, JSC::SourceCode const&, JSC::JSValue)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb8010ad	
    20. 19	WebCore::ScriptController::evaluateInWorld(WebCore::ScriptSourceCode const&, WebCore::DOMWrapperWorld*)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb2a0d2b	
    21. 20	WebCore::ScriptController::evaluate(WebCore::ScriptSourceCode const&)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb2a0efc	
    22. 21	WebCore::ScriptController::executeScript(WebCore::ScriptSourceCode const&)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb2a7c1f	
    23. 22	WebCore::HTMLTokenizer::scriptExecution(WebCore::ScriptSourceCode const&, WebCore::HTMLTokenizer::State)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb44befa	
    24. 23	WebCore::HTMLTokenizer::executeExternalScriptsIfReady()	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb451dd0	
    25. 24	WebCore::HTMLTokenizer::notifyFinished(WebCore::CachedResource*)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb451ba5	
    26. 25	WebCore::CachedScript::checkNotify()	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb47cf1a	
    27. 26	WebCore::CachedScript::data(WTF::PassRefPtr<WebCore::SharedBuffer>, bool)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb47ceb1	
    28. 27	WebCore::Loader::Host::didFinishLoading(WebCore::SubresourceLoader*)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb4a3ad9	
    29. 28	WebCore::SubresourceLoader::didFinishLoading()	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb4af359	
    30. 29	WebCore::ResourceLoader::didFinishLoading(WebCore::ResourceHandle*)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb4add10	
    31. 30	WebCore::QNetworkReplyHandler::finish()	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb62f236	
    32. 31	WebCore::QNetworkReplyHandler::qt_metacall(QMetaObject::Call, int, void**)	C:\Applications\Qt\2010.05\qt\bin\QtWebKitd4.dll	0	0xb6316b2	
    33. 32	QMetaObject::metacall	qmetaobject.cpp	237	0x6a20445c	
    34. 33	QMetaObject::activate	qobject.cpp	3272	0x6a214bbe	
    35. 34	QNetworkReply::finished	moc_qnetworkreply.cpp	152	0x68097851	
    36. 35	QNetworkReplyImplPrivate::finished	qnetworkreplyimpl.cpp	656	0x68046fcb	
    37. 36	QNetworkAccessBackend::finished	qnetworkaccessbackend.cpp	309	0x680317b6	
    38. 37	QNetworkAccessHttpBackend::finished	qnetworkaccesshttpbackend.cpp	338	0x68037895	
    39. 38	QNetworkAccessHttpBackend::replyFinished	qnetworkaccesshttpbackend.cpp	773	0x6803a597	
    40. 39	QNetworkAccessHttpBackend::downstreamReadyWrite	qnetworkaccesshttpbackend.cpp	710	0x6803a144	
    41. 40	QNetworkReplyImplPrivate::handleNotifications	qnetworkreplyimpl.cpp	367	0x68045cc9	
    42. 41	QNetworkReplyImpl::event	qnetworkreplyimpl.cpp	866	0x68047da8	
    43. 42	QApplicationPrivate::notify_helper	qapplication.cpp	4396	0x2399706	
    44. 43	QApplication::notify	qapplication.cpp	3798	0x2397012	
    45. 44	QCoreApplication::notifyInternal	qcoreapplication.cpp	732	0x6a1ff9dc	
    46. 45	QCoreApplication::sendEvent	qcoreapplication.h	215	0x6a265fbc	
    47. 46	QCoreApplicationPrivate::sendPostedEvents	qcoreapplication.cpp	1373	0x6a200a87	
    48. 47	qt_internal_proc	qeventdispatcher_win.cpp	503	0x6a222d2e	
    49. 48	USER32!OffsetRect	C:\Windows\syswow64\user32.dll	0	0x754462fa	
    50. 49	Ui_PreferencesDialog::setupUi	ui_preferencesdialog.h	568	0x570bc0	
    51. 50	USER32!IsWindow	C:\Windows\syswow64\user32.dll	0	0x75446d3a	
    52. 51	qt_fast_timer_proc	qeventdispatcher_win.cpp	432	0x6a222a8a	
    53. 52	USER32!AnyPopup	C:\Windows\syswow64\user32.dll	0	0x754477c4	
    54. 53	??		0
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    When searching for information, I came accross a bug on the Qt bugtracker : https://bugreports.qt-project.org/browse/QTBUG-18412. But I'm really not sure this is related.
    After trying to upgrade to Qt 4.7.4, I could see the issue is still there.

    I am completely lost about what lead I could follow to identify the problem.
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  2. 18th June 2012, 10:05 #2
    Vinny
    Vinny is offline Beginner
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    Default Re: Crash somewhere under sendPostedEvents(), Network related

    I am still not sure what exactly was my problem, but FYI upgrading to Qt 4.8.1 solved the issue, and enhanced performances as well.
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