Hi, Whenever I launch more than 400 processes I get the following error. But for less than 400 process every thing goes perfectly fine. I am running my code on two machines: hesh and Ubuntu (from which I am launching the jobs) root@ubuntu:/home# mpiexec -f hosts.cfg -n 500 ./hello ===================================================================================== = BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES = EXIT CODE: 139 = CLEANING UP REMAINING PROCESSES = YOU CAN IGNORE THE BELOW CLEANUP MESSAGES ===================================================================================== [proxy:0:0@hesh] HYD_pmcd_pmip_control_cmd_cb (./pm/pmiserv/pmip_cb.c:928): assert (!closed) failed [proxy:0:0@hesh] HYDT_dmxu_poll_wait_for_event (./tools/demux/demux_poll.c:77): callback returned error status [proxy:0:0@hesh] main (./pm/pmiserv/pmip.c:226): demux engine error waiting for event [mpiexec@ubuntu] HYDT_bscu_wait_for_completion (./tools/bootstrap/utils/bscu_wait.c:70): one of the processes terminated badly; aborting [mpiexec@ubuntu] HYDT_bsci_wait_for_completion (./tools/bootstrap/src/bsci_wait.c:23): launcher returned error waiting for completion [mpiexec@ubuntu] HYD_pmci_wait_for_completion (./pm/pmiserv/pmiserv_pmci.c:191): launcher returned error waiting for completion [mpiexec@ubuntu] main (./ui/mpich/mpiexec.c:405): process manager error waiting for completion Also some I time I got the following error: root@ubuntu:/home# mpiexec -f hosts.cfg -n 400 ./hello [proxy:0:1@ubuntu] send_cmd_downstream (./pm/pmiserv/pmip_pmi_v1.c:80): assert (!closed) failed [proxy:0:1@ubuntu] fn_get (./pm/pmiserv/pmip_pmi_v1.c:349): error sending PMI response [proxy:0:1@ubuntu] pmi_cb (./pm/pmiserv/pmip_cb.c:327): PMI handler returned error [proxy:0:1@ubuntu] HYDT_dmxu_poll_wait_for_event (./tools/demux/demux_poll.c:77): callback returned error status [proxy:0:1@ubuntu] main (./pm/pmiserv/pmip.c:226): demux engine error waiting for event [mpiexec@ubuntu] control_cb (./pm/pmiserv/pmiserv_cb.c:215): assert (!closed) failed [mpiexec@ubuntu] HYDT_dmxu_poll_wait_for_event (./tools/demux/demux_poll.c:77): callback returned error status [mpiexec@ubuntu] HYD_pmci_wait_for_completion (./pm/pmiserv/pmiserv_pmci.c:181): error waiting for event [mpiexec@ubuntu] main (./ui/mpich/mpiexec.c:405): process manager error waiting for completion Also I raised the open file limit on both the PCs by using ulimit -n 2048. But still the same result. The code is the simple one: /* C Example */ #include <mpi.h> #include <stdio.h> #include <stddef.h> #include <stdlib.h> int main (int argc, char* argv[]) { int rank, size; int buffer_length = MPI_MAX_PROCESSOR_NAME; char hostname[buffer_length]; MPI_Init (&argc, &argv); /* starts MPI */ MPI_Comm_rank (MPI_COMM_WORLD, &rank); /* get current process id */ MPI_Comm_size (MPI_COMM_WORLD, &size); /* get number of processes */ MPI_Get_processor_name(hostname, &buffer_length); /* get hostname */ printf( "Hello world from process %d running on %s of %d\n", rank, hostname, size ); MPI_Finalize(); return 0; } For 10000 process the program is unresponsive and I have to close the terminal to exit.t How do i solve this issue?