Confused about mpiexec

[b***@gmail.com]

Hi,
I am a newbie to mpi. I am trying to run two programs which
communicate with each other. If I use mpiexec to launch them (in a
single node) they work fine. But if I just run them separately
(without using mpiexec), they don't find each other (i.e. each of them
finds a MPI_Comm_size of 1 ). Is mpiexec mandatory for starting mpi
programs?

Thanks
Abed

[Michael Hofmann]

Post by b***@gmail.com
Hi,
I am a newbie to mpi. I am trying to run two programs which
communicate with each other. If I use mpiexec to launch them (in a
single node) they work fine. But if I just run them separately
(without using mpiexec), they don't find each other (i.e. each of them
finds a MPI_Comm_size of 1 ). Is mpiexec mandatory for starting mpi
programs?

No, it is not mandatory. However, mpiexec is the recommend way to provide
a portable process startup mechanism across different implementations of
MPI (since MPI-2?). It is supported by many MPI implementations,
especially by "free" implementations like Open MPI or MPICH2.

http://www.mpi-forum.org/docs/mpi21-report-bw/node193.htm


Michael

[Georg Bisseling]

Post by b***@gmail.com
Hi,
I am a newbie to mpi. I am trying to run two programs which
communicate with each other. If I use mpiexec to launch them (in a
single node) they work fine. But if I just run them separately
(without using mpiexec), they don't find each other (i.e. each of them
finds a MPI_Comm_size of 1 ). Is mpiexec mandatory for starting mpi
programs?
Thanks
Abed

Short answer: yes.