MPI error when running LGST about pygsti HOT 4 CLOSED

I was able to run your script successfully on multiple systems after replacing the actual data (loaded from files that I don't have) with simulated data (using pygsti.construction.generate_fake_data). I don't think this change should make any difference in the issue you're seeing, so I think there may be an issue with your MPI installation.

I've seen this same error once before, and in that case it was an MPI library error - not mpi4py but the underlying openmpi or mpich installation. To test this, please try to run the following script, which just tests whether your MPI split function works independently of anything pyGSTi related.

Put this in test.py:

from mpi4py import MPI
comm = MPI.COMM_WORLD
rank = comm.Get_rank()
color = rank / 4
spltcomm = comm.Split(color=color, key=rank)
print("Rank %d: color=%d, split-comm rank=%d" % (rank, color, spltcomm.Get_rank()))

and then execute it via mpiexec -n 16 python test.py. This produces the following output on my system (line ordering is inconsequential and may be different on your machine):

Rank 3: color=0, split-comm rank=3
Rank 5: color=1, split-comm rank=1
Rank 6: color=1, split-comm rank=2
Rank 7: color=1, split-comm rank=3
Rank 8: color=2, split-comm rank=0
Rank 9: color=2, split-comm rank=1
Rank 10: color=2, split-comm rank=2
Rank 11: color=2, split-comm rank=3
Rank 12: color=3, split-comm rank=0
Rank 13: color=3, split-comm rank=1
Rank 14: color=3, split-comm rank=2
Rank 15: color=3, split-comm rank=3
Rank 0: color=0, split-comm rank=0
Rank 1: color=0, split-comm rank=1
Rank 2: color=0, split-comm rank=2
Rank 4: color=1, split-comm rank=0

If you get an error or different output this probably means your MPI library is broken. The last time I saw this, the MPI error you cited above was reproduced by the comm.Split call in test.py.

from pygsti.

Thanks for the hints! Unfortunately the test script appears to work fine on this machine. I'll do some more investigating and try a clean install of MPI as soon as I can.

from pygsti.

@gribeill, did we decide this was due to a parser issue/malformed file?

from pygsti.

Yes, fixing the data file (no extra comments!) and a clean install of MPI seems to have fixed everything so I will close.

from pygsti.