[yt-dev] embarrassingly parallel analysis

Nathan Goldbaum goldbaum at ucolick.org
Fri Mar 16 16:43:45 PDT 2012


Hi Geoffrey,

You may need to build an mpi-capable python interpreter by hand.  See: http://mpi4py.scipy.org/docs/usrman/appendix.html#mpi-enabled-python-interpreter

Nathan Goldbaum
Graduate Student
Astronomy & Astrophysics, UCSC
goldbaum at ucolick.org
http://www.ucolick.org/~goldbaum

On Mar 16, 2012, at 4:37 PM, Geoffrey So wrote:

> Hi all, I was trying out pobj_demo.py from the workshop to see if I can parallelize my halo analysis script, but I ran into the problem where I see:
> 
> >mpirun -n 2 python pobj_demo.py --parallel
> 
> gives a warning at the end
> 
> yt : [WARNING  ] 2012-03-16 16:25:05,445 parallel_objects() is being used when parallel_capable is false. The loop is not being run in parallel. This may not be what was expected.
> 
> I've done a
> yt instinfo -u and got the latest tip:
> 
> 052fac826701 (yt) tip
> 
> but the problem persists.  I've tried printing inside the parallel loops
> 
> for sto, sp in parallel_objects(spheres, num_procs, storage = my_storage):
>     print ytcfg.getint("yt", "__global_parallel_rank")
>     sto.result = sp.quantities['TotalQuantity']('CellMass')
>     sto.result_id = '%4e %4e %4e' % (sp.center[0], sp.center[1],sp.center[2])
> 
> and I always get "0", but 20 of them, so I'm guessing that confirms the loop isn't running in parallel, and just runs the 10 spheres serially on 2 processors, so I get double the results.
> 
> Am I doing something wrong or missed something?
> 
> From
> G.S.
> 
> 
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