Re: MFC DLL - ExitInstance hang on WaitForSingleObject

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 :(