QtWebEngineCore crash when calling std::exit()

JW16

In my sample program below, the call to exit() causes a crash with the following call stack:

KernelBase.dll!00007ff898c8d862()	Unknown
CoreMessaging.dll!Cn::FailFast::Do(struct _EXCEPTION_RECORD *,struct _CONTEXT *)	Unknown
CoreMessaging.dll!Cn::FailFast::Do(struct _EXCEPTION_RECORD *)	Unknown
CoreMessaging.dll!Cn::FailFast::IndexOutOfRange(void)	Unknown
CoreMessaging.dll!Cn::Com::NativeEntry::NoContext_Prologue()	Unknown
CoreMessaging.dll!Microsoft::CoreUI::IExportMessageSession$X__ExportAdapter::CloseEndpoint(struct Microsoft::CoreUI::HENDPOINT,enum Microsoft::CoreUI::CloseEndpointFlags$C::Values)	Unknown
TextInputFramework.dll!00007ff883e45c0a()	Unknown
TextInputFramework.dll!00007ff883e459a4()	Unknown
TextInputFramework.dll!00007ff883e45894()	Unknown
TextInputFramework.dll!00007ff883e7b540()	Unknown
msctf.dll!00007ff89b0f5ba2()	Unknown
msctf.dll!00007ff89b10aee0()	Unknown
msctf.dll!00007ff89b101e97()	Unknown
Qt5WebEngineCored.dll!Microsoft::WRL::ComPtr<IUnknown>::InternalRelease() Line 235	C++
Qt5WebEngineCored.dll!Microsoft::WRL::ComPtr<IDXGIResource1>::~ComPtr<IDXGIResource1>() Line 291	C++
Qt5WebEngineCored.dll!ui::`anonymous namespace'::TSFBridgeImpl::~TSFBridgeImpl() Line 171	C++
[External Code]	
Qt5WebEngineCored.dll!deleteUnicode(void * obj) Line 269	C++
Qt5WebEngineCored.dll!`anonymous namespace'::OnThreadExitInternal(`anonymous-namespace'::TlsVectorEntry * tls_data) Line 310	C++
Qt5WebEngineCored.dll!base::internal::PlatformThreadLocalStorage::OnThreadExit() Line 345	C++
Qt5WebEngineCored.dll!OnThreadExit(void * module, unsigned long reason, void * reserved) Line 67	C++
[External Code]	
WebEngineCrash.exe!main(int argc, char * * argv) Line 15	C++
WebEngineCrash.exe!WinMain(HINSTANCE__ * __formal, HINSTANCE__ * __formal, char * __formal, int __formal) Line 97	C++

If I instead delete the app prior to calling exit(), there is no crash. Is there a way for me to completely shut down webengine and free associated resources before destructing the QApplication, so that I may call exit() before then? Or is this a Qt bug? Simply deleting the QWebView (and its page etc) prior to calling exit only seems to prevent the crash some of the time for this sample app, and doesn't seem to help at all in my real application.

#include <QtWidgets>
#include <QtWebEngineWidgets>

int main( int argc, char *argv[] )
{
    QApplication *app = new QApplication( argc, argv );
    QMainWindow *mw = new QMainWindow();
    QWebEngineView *wv = new QWebEngineView( mw );
    wv->setHtml( "<html><body>Some text</body>" );
    mw->setCentralWidget( wv );
    mw->show();
    int rc = app->exec();

    //delete app;
    exit( rc );
    delete app;

    return 0;
}

jsulm

@JW16 Why do you allocate app on the heap? Simply allocate it on the stack. Also, why do you want to call exit? Simply return rc in your return statement in main() (which is currently unreachable due to exit()). And don't forget to delete other things you allocated on the heap.

JW16

@jsulm I am just allocating on the heap here for demonstration purposes with the explicit delete call. The problem remains if I allocate on the stack. The sample below has the same problem (change the closing brace to get crash/no crash). I understand exit() is pointless in this demo, but it is being called in the real application for reasons I won't get into here. I just want to know if there is a guaranteed way to completely shut down webengine prior to the app fully destructing.

int main( int argc, char *argv[] )
{
    int rc = 0;
    {
        QApplication app( argc, argv );
        QMainWindow mw;
        QWebEngineView *wv = new QWebEngineView( &mw );
        wv->setHtml( "<html><body>Some text</body>" );
        mw.setCentralWidget( wv );
        mw.show();
        rc = app.exec();
    //}
    exit( rc );
    }

    return 0;
}

JonB

@JW16
I think you should add wv->close() before exiting, just in case that allows it to clean up better.

Also does it still crash if you compile for release? If it only happens in debug you may end up chasing your tail.

If I instead delete the app prior to calling exit(), there is no crash.

Is that not a viable workaround if you find it is the only solution?