Re: returning from worker thread

From:

"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>

Newsgroups:

microsoft.public.vc.mfc

Date:

Sat, 12 Aug 2006 14:02:28 -0400

Message-ID:

<eByn7ljvGHA.4688@TK2MSFTNGP06.phx.gbl>

Steve Russell wrote:

Even with keeping the thread alive, I find, in Release, that using

audiofile->m_pView->PostMessage(WM_AUDIO_CLEANUP)

instead of calling audiofile->CleanUp() directly in the thread

leads to trouble with the view pointer eventually. Aside from needing to
change my threading design, I would sure appreciate an explanation as to how
this could be happening. If I the thread isn't being destroyed, how is it
that the audio class pointer passed to my thread function would fail?

Your code outline has not shown any provision for thread shutdown at
program close. The likely problem with the view pointer is that the
view object gets destroyed before the thread has exited. This opens the
door for the thread to use an invalid pointer.

You must control the program shutdown sequence so the thread is gone
before any shared data, such as a view pointer, becomes invalid.
Several posts in this thread, as well as the Newcomer tutorials, point
this out and mention ways to do it. Data known to the thread must
remain valid until after the thread has exited!

--
Scott McPhillips [VC++ MVP]