MPICH currently launches individual proxy for each spawn. I think that probably attributes to the flood of fds on the server. For now, I guess the solution is to ask system admin to increase the fd limit. Feel free to open a issue at https://github.com/pmodels/mpich/issues. We'll prioritize to get it enhanced.

--
Hui

From: Mccall, Kurt E. (MSFC-EV41) via discuss <discuss@mpich.org>
Sent: Tuesday, March 22, 2022 12:55 PM
To: discuss@mpich.org <discuss@mpich.org>
Cc: Mccall, Kurt E. (MSFC-EV41) <kurt.e.mccall@nasa.gov>
Subject: [mpich-discuss] MPICH -- too many open files
 

My application, which spawns multiple subprocesses via MPI_Comm_spawn, eventually fails on one Slurm cluster as I scale up the number of processes, with the error:

 

[mpiexec@n002.cluster.pssclabs.com] HYDU_create_process (../../../../mpich-4.0.1/src/pm/hydra/utils/launch/launch.c:21): pipe error (Too many open files)

[mpiexec@n002.cluster.pssclabs.com] HYDT_bscd_common_launch_procs (../../../../mpich-4.0.1/src/pm/hydra/tools/bootstrap/external/external_common_launch.c:296): create process returned error

free(): invalid pointer

/var/spool/slurm/job235999/slurm_script: line 296: 3778907 Aborted                 (core dumped)

 

It works fine on a different (Torque) cluster for very large job sizes. 

 

“ulimit -n” (number of open files) on both machines returns 1024.  

 

I’m hoping that there is some other system setting on the Slurm cluster that would allow larger jobs.   I can provide the “-verbose” output file if that would help.

 

Thanks,

Kurt