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Annotation of q_a/samples/termq/readme.txt, revision 1.1

1.1     ! root        1:  Sample: Porting a DosStartSession Termination Queue
        !             2: 
        !             3: Summary:
        !             4: 
        !             5: This sample code demonstrates how to start multiple
        !             6: processes and wait on them to terminate. It also
        !             7: demonstrates how to convert the OS/2 method of reading from
        !             8: a "termination queue" to the equivalent Win32 API function
        !             9: calls.
        !            10: 
        !            11: In the sample, a number of child processes are started. The
        !            12: program then waits for any of them to end via the Win32
        !            13: WaitForMultipleObjects function call. As soon as a process
        !            14: terminates, the return code for the terminated process is
        !            15: retrieved and reported to the console.
        !            16: 
        !            17: More Information:
        !            18: 
        !            19: After starting child sessions with DosStartSession in OS/2,
        !            20: if you want to be notified when the child sessions
        !            21: terminate, you must create a queue and pass the handle to
        !            22: that queue into the DosStartSession call. When a child
        !            23: session ends, you receive a queue packet containing
        !            24: information about which session (by session ID) ended and
        !            25: what the termination code of that session is.
        !            26: 
        !            27: A major limitation of this method is that you are allowed
        !            28: only one termination queue per parent; this imposes some
        !            29: complications with multiple-threaded applications starting
        !            30: multiple sessions in different threads; you cannot have
        !            31: multiple threads reading from the same termination queue at
        !            32: the same time. The common solution is to have one central
        !            33: termination queue thread that reads from the termination
        !            34: queue (all of the child sessions's termination packets
        !            35: arrive in this one Queue), and process all of the
        !            36: termination queue packets for all of the other threads.
        !            37: 
        !            38: Under Win32, this complication is not there. Each thread
        !            39: that starts a new session simply waits for the new process
        !            40: handle to be signaled.
        !            41: 
        !            42: This demonstration does not involve multiple threads, nor
        !            43: does it demonstrate the complexity of the OS/2 version of
        !            44: multiple threads waiting for multiple sessions to terminate.
        !            45: It demonstrates the more simple case of starting a few
        !            46: sessions and waiting for all of them to end; the Win32
        !            47: technique used is still fully demonstrated without including
        !            48: a great deal of OS/2 code.
        !            49: 
        !            50: The following is a list of the Win32 API functions used in
        !            51: this sample:
        !            52: 
        !            53:    CloseHandle   CreateProces  GetLastErro  WaitForMultipleOb
        !            54:                  s             r            jects
        !            55: 
        !            56: 

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