Hi, I guess i need to be asking more specific questions. I saw the same issue has been raised a few years ago and apparently there was no solution for it back then, so i thought i'd check again. The question is about bypassing mpiexec and trying to connect already running processes (which already have some data in memory to share with mpi tasks) into a single communicator without having to spawn yet another process with mpiexec. Suppose one of this processes uses MPI_Comm_accept, and the other somehow know the mpi port name and would use MPI_Comm_connect() to connect to it. Everything works as long as both server and client started with mpiexec -n 1. However, without mpiexec, the same attempts cause errors and connection never happens: mpiexec@Intel-Kubu] match_arg (utils/args/args.c:159): unrecognized argument pmi_args [mpiexec@Intel-Kubu] HYDU_parse_array (utils/args/args.c:174): argument matching returned error [mpiexec@Intel-Kubu] parse_args (ui/mpich/utils.c:1596): error parsing input array [mpiexec@Intel-Kubu] HYD_uii_mpx_get_parameters (ui/mpich/utils.c:1648): unable to parse user arguments [mpiexec@Intel-Kubu] main (ui/mpich/mpiexec.c:153): error parsing parameters So, there's no way of working around the necessity to spawn an entirely new process with mpiexec? Thank you very much for your help. -Dmitriy _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss