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

Home http://arken.nmbu.no/~plesser

 

 

 

From: Robin Gilbert De Schepper <robingilbert.deschepper@unipv.it>
Date: Friday, 1 March 2024 at 12:23
To: NEST User Mailing List <users@nest-simulator.org>
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