Spawn and MPI_COMM_SPAWN with the SOFT info

[abouteiller]

It appears that there is no attribute currently defined in the PMIx_spawn operation to pass the behavior defined as a 'SOFT' spawn in MPI.

In an MPI soft spawn, the MPI_COMM_SPAWN operation requests that N new processes be spawned, but it is acceptable that N-x processes are actually created (and this is not an error).

[rhc54]

That's a new one on me - does anyone actually support that? I know OMPI doesn't. We should be able to do so here by adding a PMIX_MIN_PROCS attribute - we already have max_procs in the pmix_app_t struct.

[dsolt]

I agree that a PMIX_MIN_PROCS option would be sufficient to support MPI_COMM_SPAWN with a soft spawn and also allow for other uses.

[jjhursey]

It sounds like there is an agreement on how this looks from the PMIx side.

Action:

• Add a PMIX_MIN_PROCS attribute for PMIx_Spawn (similar in nature to PMIX_MAX_PROCS)