ExitInstance not called in MFC app

Question

Until now, I never really needed the Winapp ExitInstance() of a large MFC (Single Document Interface if it matters) app I'm working on. But now I do, mainly to cleanup memory alocations, unload some DLLs, etc. Well I soon learned by the obvious memory leaks and such that ExitInstance was not being called. Have I missed something obvious? Do I need to manually add something to the message map to make sure my ExitInstance override is called?

I guess i can do my cleanup elsewhere, but it's the best place if I can get it to run. Interestingly, I found quite a few instances of this by typing strings like "ExitInstance never called" and such into Google, and in no case were any real answers offered. The app normally closes when someone clicks the close box or the "Exit" from the File menu, and the OnClose() of the mainframe window certainly does always get called. I even tried forcing things by putting AfxGetMainWnd()->DestroyWindow(); in that mainframe OnClose() event, but still I can't get the ExitInstance() to actually run. Maybe it's just a big dummy function? Or maybe I'M just a big dummy? :-)

Answer 1

I had a similar problem to you...mine was caused by mixing Unicode and MBCS built code....maybe that was your underlying cause?

I had to convert an MBCS application to Unicode, but it was impossible to convert the whole project, so I had to mix Unicode compiled (the application) and MBCS compiled code (the DLLs).

Some of the MBCS DLLs were MFC extension DLLs, others were regular DLLs.

One of the MFC extension DLLs contained resources (bitmap image list, and common dialogs).

I didn't convert the DLL to UNICODE because it had a lot of dependent DLLs which would also have had to be converted, and in addition I didn't need the controls in the common dialogs to support Unicode text.

So I kept the DLL as MBCS, and used AfxSetResourceHandle prior to using any class in the MBCS DLL that used resources.....this was to make the resources get pulled from the DLL directly, instead of through the MFC resource chain, because MFC couldn't find the non-unicode resources otherwise.

I guess MFC doesn't like it when you have a mix of Unicode and non-unicode compiled code containing resources.....lookups in the resource chain fail (I guess has something to do with the conversion of resource IDs to an ID string i.e. via MAKEINTRESOURCE).

I made the main application UNICODE, and made sure the C++ headers of classes in the MBCS DLLs used CStringA in the function prototypes, or accepted wide strings and did the conversion internally.

What I found was my application wouldn't exit properly...it would stay in the MFC CWinThread::PumpMessage/AfxInternalPumpMessage() call, and ExitInstance would never be called.

To solve it, in my CMainFrame::OnDestroy() I put the following as the last 2 statements:

void CMainFrame::OnDestroy() 
{
    ....

    CFrameWnd::OnDestroy();

    AfxPostQuitMessage(0);
}