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.