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Help for synchronization

Posted on 2004-09-02
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Last Modified: 2013-11-20
hi
I need some help for threading concept.
Suppose we have three thread. And I want to execute all this thread before executing any code.After executing this three thread, I need to execute a block of code.How can I do this.What threading method will be usefull.please give some example and also give some link for threading concept.
Regards
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Question by:nclgaurav
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2 Comments
 
LVL 13

Expert Comment

by:SteH
ID: 11962172
What is the reason for three threads if nothing is executed in the main thread before all of them have finished. My logic for using a thread is to keep the main thread reactive/responsive. When you want to block it until all threads have finished I would say one thread can be ommited and its tasks should be executed (as a function?) in the main one.

For general worker threads:
http://www.flounder.com/mvp_tips.htm#Using%20Worker%20Threads

Waiting for threads to finish:
generate an event which is set when the thread is finished. In the main thread you do
WaitForMultipleObject() with all thread events until all of them are set.
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LVL 16

Accepted Solution

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nonubik earned 50 total points
ID: 11962758
You can do a while loop to check whether the threads are finished with
GetExitCodeThread(
  HANDLE hThread,
  LPDWORD lpExitCode
);
If the exit code is STILL_ACTIVE continue the loop.

while(1)
{
  DWORD dwExitCode;
  int i=0;
  if(GetExitCodeThread(hThread1, &dwExitCode))
    if(dwExitCode == STILL_ACTIVE)
      i++;
   //same for the other threads

  if(!i)
     break; //no thread active
  Sleep(1);
}

Or just the WaitForMultipleObject way, but you can pass as handles the threads handles, not some thread-event. When one of the threads finishes, it wil signal.
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