Hi, Edscott! I think you need to call MPI_Comm_disconnect() in child processes. Eugene. ________________________________________ From: [email protected] [[email protected]] On Behalf Of Edscott Wilson [[email protected]] Sent: Thursday, May 30, 2013 12:48 PM To: [email protected] Subject: [mpich-discuss] MPI_COMM_Spawn leave children processes in active wait MPI_COMM_Spawn leave children processes in active wait until parent process is done. I've just checked latest ompi and behavior is the same as in mpich. So be it. -- ------------------------------------------------------------------------------------ Dr. Edscott Wilson Garcia Applied Mathematics and Computing Mexican Petroleum Institute