[NEST Users] Re: Opt out of MPI during an MPI run

Hi Robin, We added this error message intentionally because it had happened a few times that users ran a NEST compiled without MPI through mpirun and the like, which results in N programs running in parallel without talking to each other. So I would not want to remove this error message. If you should consider it absolutely necessary, I would accept a command-line option to NEST to tell it to ignore mpi-invocation of a NEST compiled without MPI. Best, Hans Ekkehard -- Prof. Dr. Hans Ekkehard Plesser Department of Data Science Faculty of Science and Technology Norwegian University of Life Sciences PO Box 5003, 1432 Aas, Norway Phone +47 6723 1560 Email hans.ekkehard.plesser@nmbu.no<mailto:hans.ekkehard.plesser@nmbu.no> Home http://arken.nmbu.no/~plesser From: Robin Gilbert De Schepper &lt;robingilbert.deschepper(a)unipv.it&gt; Date: Friday, 1 March 2024 at 12:23 To: NEST User Mailing List &lt;users(a)nest-simulator.org&gt; Subject: [NEST Users] Opt out of MPI during an MPI run Hi! Is there a way to disable the following fatal error? Perhaps an environment variable to tell NEST not to try to initialize MPI: [FATAL] [2024.3.1 12:15:12 /home/robin/git/nest-simulator/nestkernel/mpi_manager.cpp:203 @ MPIManager::initialize()] : You seem to be using NEST via an MPI launcher like mpirun, mpiexec or srun although NEST was not compiled with MPI support. Please see the NEST documentation about parallel and distributed computing. Exiting. I know I could rebuild with MPI support, and set the communicator to a communicator containing just that rank, on each rank, but this is during unit testing where nest is just imported, so a quick opt-out would be less work. -- Robin De Schepper, PhD (they/them) Department of Brain and Behavioral Sciences Unit of Neurophysiology University of Pavia, Italy Via Forlanini 6, 27100 Pavia - Italy Tel: (+39) 038298-7607 http://www-5.unipv.it/dangelo/