There is a name for my pain and it is “OpenMPI + PMIx”. :)
I’m looking at upgrading SLURM from 16.05.11 to 17.11.05 (bear with me, this is
not a SLURM question).
After building SLURM 17.11.05 with
‘--with-pmix=/opt/pmix/1.1.5:/opt/pmix/2.1/1’ and installing a test instance, I
see
$ srun --mpi=list
srun: MPI types are...
srun: pmix
srun: pmi2
srun: pmix_v2
srun: none
srun: openmpi
Seems reasonable.
Now, we have applications built with OpenMPI 3.0.0 and 3.1.0 linked against
/opt/pmix/1.1.5 (--with-pmix=/opt/pmix/1.1.5). When I attempt to launch these
applications using,
srun —mpi=pmix <some mpi app>
I get the following ...
[c1a-s18.ufhpc:17995] Security mode none is not available
[c1a-s18.ufhpc:17995] PMIX ERROR: UNREACHABLE in file src/client/pmix_client.c
at line 199
--------------------------------------------------------------------------
The application appears to have been direct launched using "srun",
but OMPI was not built with SLURM's PMI support and therefore cannot
execute. There are several options for building PMI support under
SLURM, depending upon the SLURM version you are using:
version 16.05 or later: you can use SLURM's PMIx support. This
requires that you configure and build SLURM --with-pmix.
Versions earlier than 16.05: you must use either SLURM's PMI-1 or
PMI-2 support. SLURM builds PMI-1 by default, or you can manually
install PMI-2. You must then build Open MPI using --with-pmi pointing
to the SLURM PMI library location.
Please configure as appropriate and try again.
--------------------------------------------------------------------------
*** An error occurred in MPI_Init
*** on a NULL communicator
*** MPI_ERRORS_ARE_FATAL (processes in this communicator will now abort,
*** and potentially your MPI job)
———————————————————————————————————————————————————————
So slurm/srun appear to have library support for both pmix and pmix_v2 and
OpenMPI 3.0.0 and OpenMPI 3.1.0 both have pmix support (1.1.5) since we launch
them every day with “srun —mpi=pmix” under slurm 16.05.11.
Is this a bug? Am I overlooking something? Is it possible to transition to
OpenMPI 3.x + PMIx 2.x + SLURM 17.x without rebuilding (essentially) everything
(including all applications)?
Charlie Taylor
UF Research Computing
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