[yt-dev] answer testing in parallel

[Kacper Kowalik]

On 07/28/2014 04:05 PM, Britton Smith wrote:
> Hi all,
> 
> Does anyone, perhaps Kacper, know if we can do any answer testing in
> parallel?  I would like to add a test for the rockstar halo finder, but it
> has to be run with a minimum of 3 MPI tasks.  This would not require 3
> actual CPUs to run on since each the tasks sort of take turns.  Is there a
> way to do this?

Hi Britton,
bear in mind that I don't have any experience with mixing mpi and nose,
but I'd go for mpi_spawn. Roughly, it would look like that:

shakuras ~/codes/britton $ cat test_foo.py
#!/usr/bin/env python

from mpi4py import MPI
import sys
def test_blah():
    comm = MPI.COMM_SELF.Spawn("blah.py", maxprocs=3)
    status = MPI.Status()
    comm.Disconnect()
    assert True

shakuras ~/codes/britton $ cat blah.py
#!/usr/bin/env python

from mpi4py import MPI
import sys

comm = MPI.Comm.Get_parent()
size = comm.Get_size()
rank = comm.Get_rank()

sys.stderr.write("size = %i, rank = %i\n" % (size, rank))
comm.Disconnect()


blah.py would be an actual test in your case. I think it'd be safer to
evaluate if test passed/failed after comm.Disconnect() so that mpi
processes are not left hanging, but it needs to be verified empirically ;)

Cheers,
Kacper

P.s. There's a project that does something similar:
https://github.com/dagss/mpinoseutils  but I don't know its state.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 884 bytes
Desc: OpenPGP digital signature
URL: <http://lists.spacepope.org/pipermail/yt-dev-spacepope.org/attachments/20140728/46682377/attachment.pgp>