After you set breakpoints, you can start all of the parallel tasks with the Process Window
Group > Go command.
Be very cautious in placing breakpoints at or before a line that calls
MPI_Init() or
MPL_Init() because timeouts can occur while your program is being initialized. After you allow the parallel processes to proceed into the
MPI_Init() or
MPL_Init() call, allow all of the parallel processes to proceed through it within a short time. For more information on this, see
IBM PE Debugging Tips.