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maybempi

maybempi

Run the same code under mpirun and as a plain python script, without starting MPI in the serial run.
Get startedView on GitHub
import maybempi


MPI = maybempi.get_mpi()  # mpi4py.MPI under mpirun/srun, a serial stand-in otherwise
comm = MPI.COMM_WORLD
total = comm.allreduce(local_total, op=MPI.SUM)

No MPI in serial runs

Importing mpi4py.MPI starts MPI, which costs close to a second. maybempi decides from the launcher’s environment variables and never imports mpi4py in a serial run.

One code path

The stand-in has the module constants and communicator methods of mpi4py, with the results MPI gives on one process.

Loud when unsupported

Methods the stand-in does not implement raise AttributeError instead of silently doing nothing.

No dependencies

Pure Python. mpi4py is only needed for MPI runs, NumPy only for array buffers.

Start here

Section titled “Start here”
Installationpip install maybempi, with or without mpi4py.
QuickstartReplace from mpi4py import MPI.
How the decision is madeLauncher variables, the MAYBEMPI override and Slurm.
The serial stand-inWhat each call does on one process.