Hi Howard,
thanks, but my Slurm 24.05 definitely has pmix support (visible in "srun
–mpi=list") and it uses it through "MpiDefault=pmix" in slurm.conf. The
mentioned problem also appears if I use a container with OpenMPI
compiled against same pmix as Slurm 24.05 (which is Ubuntu 24.04 package
libpmix2t64 in this case).
In the meantime I found this bug report:
https://github.com/open-mpi/ompi/issues/12146, which sounds very
similar. I haven't completely worked through it, they use a different
container solution and things seem to be COMPLICATED...but still...
Also I found that my Slurm 24.05 works with OpenMPI outside of
containers (with ompi examples or python mpi4py).
Matthias
Am 27.03.25 um 15:46 schrieb Pritchard Jr., Howard:
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.quan...@gmail.com>
*Date: *Thursday, March 27, 2025 at 7:41 AM
*To: *Matthias Leopold <matthias.leop...@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.leop...@meduniwien.ac.at
<mailto:matthias.leop...@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.com <mailto:slurm-
us...@lists.schedmd.com> <mailto:slurm-users@lists.schedmd.com
<mailto: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
>
>
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--
Medizinische Universität Wien
Matthias Leopold
IT Services & strategisches Informationsmanagement
Enterprise Technology & Infrastructure
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