George, Thanks, that was it!
Kurt From: George Bosilca <bosi...@icl.utk.edu> Sent: Wednesday, March 16, 2022 4:38 PM To: Open MPI Users <users@lists.open-mpi.org> Cc: Mccall, Kurt E. (MSFC-EV41) <kurt.e.mcc...@nasa.gov> Subject: [EXTERNAL] Re: [OMPI users] MPI_Intercomm_create error I see similar issues on platforms with multiple IP addresses, if some of them are not fully connected. In general, specifying which interface OMPI can use (with --mca btl_tcp_if_include x.y.z.t/s) solves the problem. George. On Wed, Mar 16, 2022 at 5:11 PM Mccall, Kurt E. (MSFC-EV41) via users <users@lists.open-mpi.org<mailto:users@lists.open-mpi.org>> wrote: I’m using OpenMpi 4.1.2 under Slurm 20.11.8. My 2 process job is successfully launched, but when the main process rank 0 attempts to create an intercommunicator with process rank 1 on the other node: MPI_Comm intercom; MPI_Intercomm_create(MPI_COMM_SELF, 0, MPI_COMM_WORLD, 1, <tag>, &intercom); OpenMpi spins deep inside the MPI_Intercomm_create code, and the following error is reported: WARNING: Open MPI accepted a TCP connection from what appears to be a another Open MPI process but cannot find a corresponding process entry for that peer. This attempted connection will be ignored; your MPI job may or may not continue properly. The output resulting from using the mpirun arguments “--mca ras_base_verbose 5 --display-devel-map --mca rmaps_base_verbose 5” is attached. Any help would be appreciated.
