return of WaitForMultipleObject()

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In my MFC dialog-based application there is one parent thread and inside this parent thread I am having multiple (not a fixed number) of child threads.
The child thread pointers are declared as CWinThread *Thread[2]; and used in a loop like:

while(codn==true)
{
  Thread[0]=AfxBeginThread(Thread1,LPVOID(NULL));
  Thread[1]=AfxBeginThread(Thread2,LPVOID(NULL));
}

The above while loop iterates no. of times.
I m using WaitForMultipleObject() to wait for all child thread to signal before the termination of the parent thread.
The return of WaitForMultipleObjects is always -1.

The child thread variables gets overwritten?
Is there any other method to assign the child thread variables that are not fixed and will depends on runtime...

Please help! How can I wait for all the child threads to complete their tasks before terminating the parent thread?

Posted 14-Apr-10 20:24pm

sksksksksksksks

Updated 25-Apr-10 22:16pm

Moak

v4

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Ajay Vijayvargiya · Answer 1 · 2010-04-23T10:09:00

AfxBeginThread returns a CWinThread object, which deletes itself when the thread procedure returns.

From MSDN:
dwCreateFlags
Specifies an additional flag that controls the creation of the thread. This flag can contain one of two values:

CREATE_SUSPENDED Start the thread with a suspend count of one. Use CREATE_SUSPENDED if you want to initialize any member data of the CWinThread object, such as m_bAutoDelete or any members of your derived class, before the thread starts running. Once your initialization is complete, use CWinThread::ResumeThread to start the thread running. The thread will not execute until CWinThread::ResumeThread is called.

Eugen Podsypalnikov · Answer 2 · 2010-04-14T20:36:00

The loop above does overwrite your vars,
so you will not can to reference the created threads...

How do you use the function WaitForMultipleObjects(..) exactly ? :)

sksksksksksksks wrote:
Is there any other method to assign the child thread variables that are not fixed and will depends on runtime...

How many threads do you need ?
If they are two only then you do not need the loop :)

Assumed your vars are valid:

void CYourDialog::EndWorkers()
{
  /*volatile bool*/ m_bExitThreads = true; // signal the threads
                                           // about the exiting
  if (m_Thread[0] && m_Thread[1]) {
    HANDLE hThreads[2] = {
      m_Thread[0]->m_hThread,
      m_Thread[1]->m_hThread
    };
 
    WaitForMultipleObjects(2,
                           hThreads,
                           TRUE,
                           INFINITE);
 
    m_Thread[0] = m_Thread[1] = NULL;
  }
}

Adam Roderick J · Answer 3 · 2010-04-25T21:52:00

Actually dont consider child parent relation for a thread. :)
Main Thread and worker thread is a better description.
Well WaitForMultipleObjects itself it enough but you have mention the Thread count so that waits for the all threads to exit :)
But just go through this code snippet mentioned in below link, a sample code that waits for the all thread to terminate [^]

return of WaitForMultipleObject()

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