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From: Aurelien Bouteiller (bouteill_at_[hidden])
Date: 2007-07-26 18:22:07

> mpirun -hostfile big_pool -n 10 -host 1,2,3,4 application : -n 2 -host
> 99,100 ft_server

This will not work: this is a way to launch MIMD jobs, that share the
same COMM_WORLD. Not the way to launch two different applications that
interact trough Accept/Connect.

Direct consequence on simple NAS benchmarks are:
* if the second command does not use MPI-Init, then the first
application locks forever in MPI-Init
* if both use MPI init, the MPI_Comm_size of the jobs are incorrect.

bouteill_at_dancer:~$ ompi-build/debug/bin/mpirun -prefix
/home/bouteill/ompi-build/debug/ -np 4 -host node01,node02,node03,node04
NPB3.2-MPI/bin/lu.A.4 : -np 1 -host node01 NPB3.2-MPI/bin/mg.A.1

 NAS Parallel Benchmarks 3.2 -- LU Benchmark

     Warning: program is running on 5 processors
     but was compiled for 4
 Size: 64x 64x 64
 Iterations: 250
 Number of processes: 5