Re: Destructors & Class Inheritance

25 Apr 2006 17:30:44 -0700
Interesting. Thanks Igor, I actually though of you when I wrote this
message, telling myself I would really like to have an answer from
Igor.. ! Really.

Ok, so here's the real story: I am using MFC CWinThread class to spawn
a user interface thread. As you may know CWinThread uses a method
called Delete() which does exactly as above: delete this; when
m_bAutoDelete is set.

Now in order to shut down this thread properly, I call
CWinThread->PostThreadMessage(WM_QUIT, 0, 0) inside the destructor of
my worker thread (the one that started the UI thread) and since I want
to wait for the thread to complete its shut down process, I use an
event which is set in my CWinThread destructor.

So far so good, everything works like a charm, except that 1 out of
30-40 times I get a CWinThread object leak... This would mean I have a
race condition somewhere. Here's my code (stripped for clarity):

// CWorkerThread

CWorkerThread::CWorkerThread() :
  m_event( FALSE ) // CEvent initially not owned
m_event.ResetEvent(); // Non signaled
m_pUIThread = new CUIWinThread( this );

m_pUIThread->PostThreadMessage( WM_QUIT, 0, 0 );
// Wait for UI thread to quit

// CUIThread

CUIThread::CUIThread( CWorkerThread *pOwnerThread ) :
  m_pOwnerThread( pOwnerThread )


Now when CUIThread's destructor is called, it is called *before*
CWinThread's destructor (according to our previous discussion), which
means the event is fired before the thread has actually completely
cleaned up... This is how I see the problem.

Ideally, I would need to fire the event at the very end of the
destruction of CUIThread.

Any ideas?

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