HI Matthias,
It looks like the Open MPI in the containers was not built with PMI1 or PMI2 support, so its defaulting to using PMIx. You are seeing this error message because the call within Open MPI 4.1.x’s runtime system to PMIx_Init returned an error. Namely that there was no PMIx server to connect to.
Not sure why the behavior would have changed between your SLURM variants.
If you run
srun –mpi=list
does it show a pmix option?
If not you need to rebuild slurm with the –with-pmix config option. You may want to check what pmix library is installed in the containers and if possible use that version of PMIx when rebuilding SLURM.
Howard
From: Davide DelVento via slurm-users slurm-users@lists.schedmd.com Reply-To: Davide DelVento davide.quantum@gmail.com Date: Thursday, March 27, 2025 at 7:41 AM To: Matthias Leopold matthias.leopold@meduniwien.ac.at Cc: Slurm User Community List slurm-users@lists.schedmd.com Subject: [EXTERNAL] [slurm-users] Re: [EXTERN] Re: Slurm 24.05 and OpenMPI
Hi Matthias, I see. It does not freak me out. Unfortunately I have very little experience working with MPI-in-containers, so I don't know the best way to debug this. What I do know is that some ABIs in Slurm change with Slurm major versions and dependencies need to be recompiled with newer versions of the latter. So maybe trying to recompile the OpenMPI-inside-the-container against the version of Slurm you are utilizing is the first I would try if I were in your shoes Best, Davide
On Thu, Mar 27, 2025 at 4:19 AM Matthias Leopold <matthias.leopold@meduniwien.ac.atmailto:matthias.leopold@meduniwien.ac.at> wrote: Hi Davide,
thanks for reply. In my clusters OpenMPI is not present on the compute nodes. The application (nccl-tests) is compiled inside the container against OpenMPI. So when I run the same container in both clusters it's effectively the exact same OpenMPI version. I hope you don't freak out hearing this, but this worked with Slurm 21.08. I tried using a newer container version and another OpenMPI (first it was Ubuntu 20.04 with OpenMPI 4.1.7 from NVIDIA repo, second is Ubuntu 24.04 with Ubuntu OpenMPI 4.1.6), but the error is the same when running the container in Slurm 24.05.
Matthias
Am 26.03.25 um 21:24 schrieb Davide DelVento:
Hi Matthias, Let's take the simplest things out first: have you compiled OpenMPI yourself, separately on both clusters, using the specific drivers for whatever network you have on each? In my experience OpenMPI is quite finicky about working correctly, unless you do that. And when I don't, I see exactly that error -- heck sometimes I see that even when OpenMPI is (supposed?) to be compiled and linked correctly and in such cases I resolve it by starting jobs with "mpirun --mca smsc xpmem -n $tasks whatever-else-you-need" (which obviously may or may not be relevant for your case). Cheers, Davide
On Wed, Mar 26, 2025 at 12:51 PM Matthias Leopold via slurm-users <slurm-users@lists.schedmd.commailto:slurm-users@lists.schedmd.com <mailto:slurm-users@lists.schedmd.commailto:slurm-users@lists.schedmd.com>> wrote:
Hi, I built a small Slurm 21.08 cluster with NVIDIA GPU hardware and NVIDIA deepops framework a couple of years ago. It is based on Ubuntu 20.04 and makes use of the NVIDIA pyxis/enroot container solution. For operational validation I used the nccl-tests application in a container. nccl-tests is compiled with MPI support (OpenMPI 4.1.6 or 4.1.7) and I used it also for validation of MPI jobs. Slurm jobs use "pmix" and tasks are launched via srun (not mpirun). Some of the GPUs can talk to each other via Infiniband, but MPI is rarely used at our site and I'm fully aware that my MPI knowledge is very limited. Still it worked with Slurm 21.08. Now I built a Slurm 24.05 cluster based on Ubuntu 24.04 and started to move hardware there. When I run my nccl-tests container (also with newer software) I see error messages like this: [node1:21437] OPAL ERROR: Unreachable in file ext3x_client.c at line 111 -------------------------------------------------------------------------- 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) [node1:21437] Local abort before MPI_INIT completed completed successfully, but am not able to aggregate error messages, and not able to guarantee that all other processes were killed! One simple question: Is this related to https://github.com/open-mpi/ompi/issues/12471<https://urldefense.com/v3/__https:/github.com/open-mpi/ompi/issues/12471__;!!Bt8fGhp8LhKGRg!HbDrlb62ejeR1sQXdPbyKWMgWXxLYYaShWrhQ7F2zfXYudPXia0kOaOmWAp-bgj1LUQ5qYPmxmh9MuZD3Z7HigijM60$> <https://github.com/open-mpi/ompi/issues/12471<https://urldefense.com/v3/__https:/github.com/open-mpi/ompi/issues/12471__;!!Bt8fGhp8LhKGRg!HbDrlb62ejeR1sQXdPbyKWMgWXxLYYaShWrhQ7F2zfXYudPXia0kOaOmWAp-bgj1LUQ5qYPmxmh9MuZD3Z7HigijM60$>>? If so: is there some workaround? I'm very grateful for any comments. I know that a lot of detail information is missing, but maybe someone can still already give me a hint where to look. Thanks a lot Matthias -- slurm-users mailing list -- slurm-users@lists.schedmd.com<mailto:slurm-users@lists.schedmd.com> <mailto:slurm-users@lists.schedmd.com<mailto:slurm-users@lists.schedmd.com>> To unsubscribe send an email to slurm-users-leave@lists.schedmd.com<mailto:slurm-users-leave@lists.schedmd.com> <mailto:slurm-users-leave@lists.schedmd.com<mailto:slurm-users-leave@lists.schedmd.com>>