cobaya run --test flag incompatible with MPI

[AdamOrmondroyd]

When invoking cobaya run with the --test flag, each thread returns an error stating that mpi4py is not installed, even though it is.

[output] *ERROR* File runs/camb_poly.input.yaml.locked is locked.
You may be running multiple jobs with the same output when you intended to run with MPI. Check that mpi4py is correctly installed and configured (using the same mpi as mpirun/mpiexec); e.g. try the test at
https://cobaya.readthedocs.io/en/latest/installation.html#mpi-parallelization-optional-but-encouraged
mpi4py is NOT currently installed.

Removing --test and making no other changes solves the problem.

[cmbant]

This is only a problem with polychord ?

[AdamOrmondroyd]

I'm finding the same problem with both polychord and mcmc

[cmbant]

--test is intended to test the config not run as mpi. If you just execute --test normally, rather than using mpirun/mpiexec, is it OK?

[AdamOrmondroyd]

It works fine without mpirun etc, or using mpirun with a single task. I've also found the same problem with the evaluate sampler as mcmc and polychord.

I am running cobaya on CSD3, and I expected that I'd be able to just add --test to my sbatch script in order to quickly check that everything was okay before taking my eye off it. If it's not intended to be used this way, maybe this should be mentioned in the docs? Apologies if it is and I've missed it.

[cmbant]

I see your point. We made --test run without mpi so it would work on head nodes where mpi is not allowed, with intention that it is run interactively on the command line. I added one comment to the docs in https://github.com/CobayaSampler/cobaya/pull/222/commits/bc9dd635b65efa83eeda168ed58d1d68074287b8

[cmbant]

Also run-time warning in https://github.com/CobayaSampler/cobaya/commit/9471699168d7440498004acdbbf02e56dd2ea0dd