[MPICH] Interactive jobs with MPICH-1.2.6

[Rusty Lusk]

From: "Jeffrey B. Layton" <laytonjb at charter.net>
Subject: [MPICH] Interactive jobs with MPICH-1.2.6
Date: Fri, 15 Jul 2005 11:54:38 -0400

> Good morning,
> 
>    I've never run interactive jobs before but I need to run
> a code that requires input on rank 0 process. Are there
> any gotchas or hints to running this kind of a job on
> a cluster? Should I start the rank 0 process on the master
> node and let the other nodes be rank 1 to (n-1)?
> 
> Thank!
> Jeff

The MPI Standard does not specify the behavior of stdin, stdout, and
stderr, since MPI was designed to be portable to systems where those
concepts do not exist.  Therefore the behavior is
implmentation-dependent.  Many MPI implementations (including MPICH and
MPICH2) by default direct the stdin of mpirun or mpiexec to the MPI
process that has rank 0 and the stdout of all processes to the stdout of
mpirun or mpiexec.  In MPICH2 there are a number of other options as
well, but the default behavior is often enough for interactive jobs.

Rusty Lusk