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 [https://opengraph.githubassets.com/7cbf378518c55cfe4549cfe44dfb9b74ceb606f933d674d797658393c7979a52/pmodels/mpich]<https://github.com/pmodels/mpich/issues> Issues · pmodels/mpich - GitHub<https://github.com/pmodels/mpich/issues> Official MPICH Repository. Contribute to pmodels/mpich development by creating an account on GitHub. github.com ________________________________ From: Mccall, Kurt E. (MSFC-EV41) via discuss <[email protected]> Sent: Tuesday, March 22, 2022 12:55 PM To: [email protected] <[email protected]> Cc: Mccall, Kurt E. (MSFC-EV41) <[email protected]> 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: [[email protected]] HYDU_create_process (../../../../mpich-4.0.1/src/pm/hydra/utils/launch/launch.c:21): pipe error (Too many open files) [[email protected]] 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