OK, but then on this other machine it hangs. This one is using SLURM, so I’m not exactly sure but I think this tells me the OpenMPI version:
siegel@cisc372:~$ mpiexec.openmpi --version mpiexec.openmpi (OpenRTE) 2.1.1 Report bugs to http://www.open-mpi.org/community/help/ siegel@cisc372:~/372/code/mpi/io$ mpicc io_byte_shared.c siegel@cisc372:~/372/code/mpi/io$ srun -n 4 ./a.out srun: job 143344 queued and waiting for resources srun: job 143344 has been allocated resources Proc 0: file has been opened. Proc 0: About to write to file. Proc 1: file has been opened. Proc 2: file has been opened. Proc 3: file has been opened. ^Csrun: interrupt (one more within 1 sec to abort) srun: step:143344.0 tasks 0-3: running ^Csrun: sending Ctrl-C to job 143344.0 srun: Job step aborted: Waiting up to 32 seconds for job step to finish. slurmstepd-beowulf: error: *** STEP 143344.0 ON beowulf CANCELLED AT 2020-06-05T19:03:59 *** > On Jun 5, 2020, at 6:55 PM, Jeff Squyres (jsquyres) <jsquy...@cisco.com> > wrote: > > On Jun 5, 2020, at 6:35 PM, Stephen Siegel via users > <users@lists.open-mpi.org> wrote: >> >> [ilyich:12946] 3 more processes have sent help message help-mpi-btl-base.txt >> / btl:no-nics >> [ilyich:12946] Set MCA parameter "orte_base_help_aggregate" to 0 to see all >> help / error messages > > It looks like your output somehow doesn't include the actual error message. > That error message was sent to stderr, so you may not have captured it if you > only did "mpirun ... > foo.txt". The actual error message template is this: > > ----- > %s: A high-performance Open MPI point-to-point messaging module > was unable to find any relevant network interfaces: > > Module: %s > Host: %s > > Another transport will be used instead, although this may result in > lower performance. > > NOTE: You can disable this warning by setting the MCA parameter > btl_base_warn_component_unused to 0. > ----- > > This is not actually an error -- just a warning. It typically means that > your Open MPI has support for HPC-class networking, Open MPI saw some > evidence of HPC-class networking on the nodes on which your job ran, but > ultimately didn't use any of those HPC-class networking interfaces for some > reason and therefore fell back to TCP. > > I.e., your program ran correctly, but it may have run slower than it could > have if it were able to use HPC-class networks. > > -- > Jeff Squyres > jsquy...@cisco.com >