Hi I am trying to run simple hello world program on cluster nodes. I am running it by following command but getting errors: 

Command:  /usr/lib64/mpich/bin/mpirun -n 4 -f host_file ./mpi_hello_world

errors:
[mpiexec@md-lin-01.mcs.kent.edu] control_cb (./pm/pmiserv/pmiserv_cb.c:202): assert (!closed) failed
[mpiexec@md-lin-01.mcs.kent.edu] HYDT_dmxu_poll_wait_for_event (./tools/demux/demux_poll.c:77): callback returned error status
[mpiexec@md-lin-01.mcs.kent.edu] HYD_pmci_wait_for_completion (./pm/pmiserv/pmiserv_pmci.c:197): error waiting for event
[mpiexec@md-lin-01.mcs.kent.edu] main (./ui/mpich/mpiexec.c:331): process manager error waiting for completion


Before running the command I am setting variables MPIRUN =mpi diretory and MPI_HOSTS=host_file. The "host_file" has four nodes and they can ssh to each other without password.

MPICH version I am running is: 3.0.4. The MPI code is attached.

Any help to solve the problem please?