Hi all,

We’re running a small slurm dev cluster on Ubuntu and are facing issues with MPI/PMIx after upgrading slurm from 23.02.5 to 23.11.3.

The first job step to use MPI within a job fails roughly 80% of the time but following attempts to use MPI within the same job work fine. For the failing job step we see this error after hitting the MPI timeout:

slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_reset_if_to: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:741: 0x55a03f8d7a90: collective timeout seq=0 slurmstepd: error: mpi/pmix_v4: pmixp_coll_log: hpc-d-msh-01a02 [1]: pmixp_coll.c:286: Dumping collective state slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:759: 0x55a03f8d7a90: COLL_FENCE_RING state seq=0 slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:762: my peerid: 1:hpc-d-msh-01a02 slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:769: neighbor id: next 0:hpc-d-msh-01a01, prev 0:hpc-d-msh-01a01 slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:778: Context ptr=0x55a03f8d7b08, #0, in-use=0 slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:778: Context ptr=0x55a03f8d7b40, #1, in-use=0 slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:778: Context ptr=0x55a03f8d7b78, #2, in-use=1 slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:787: seq=0 contribs: loc=1/prev=1/fwd=0 slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:791: neighbor contribs [2]: slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:824: done contrib: hpc-d-msh-01a01 slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:826: wait contrib: - slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:828: status=PMIXP_COLL_RING_FINILIZE slurmstepd: error: mpi/pmix_v4: pmixp_coll_ring_log: hpc-d-msh-01a02 [1]: pmixp_coll_ring.c:831: buf (offset/size): 0/33362 [hpc-d-msh-01a01.tds.hpc.barf1.com:47652] pml_ucx.c:178 Error: Failed to receive UCX worker address: Not found (-13) [hpc-d-msh-01a01.tds.hpc.barf1.com:47652] pml_ucx.c:477 Error: Failed to resolve UCX endpoint for rank 31 [hpc-d-msh-01a01:47652] *** An error occurred in MPI_Send [hpc-d-msh-01a01:47652] *** reported by process [683360612,0] [hpc-d-msh-01a01:47652] *** on communicator MPI_COMM_WORLD [hpc-d-msh-01a01:47652] *** MPI_ERR_OTHER: known error not in list [hpc-d-msh-01a01:47652] *** MPI_ERRORS_ARE_FATAL (processes in this communicator will now abort, [hpc-d-msh-01a01:47652] *** and potentially your MPI job) slurmstepd: error: *** STEP 1890.0 ON hpc-d-msh-01a01 CANCELLED AT 2024-02-14T16:14:52 ***

OpenMPI/PMIx versions have not changed and downgrading slurm to 23.02.5 seems to resolve the issue. We’d appreciate any pointers anyone might have.

Thanks

Oli

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