mpich2 and python

[Jason Swails]

Hi Joerg,

MPICH2 uses python fairly extensively (the mpirun and mpiexec executables
are actually just python scripts, as are mpd/mpdboot).  Those developers
tend to hard-code the python version that they use into their execution
since they know that works and will be free of any new bugs that may get
introduced by new versions.  That's the same reason a lot of OS vendors
strap an old, stripped-out python distribution with their OS: their system
python utilities work just fine with that version and they're hesitant to
invest the time to ensure upwards compatibility (especially when Python
makes a jump like 2.x -> 3.x).  You should not change this to python2.7
because mpirun/mpiexec are unlikely to work, since the top line stays as:

#!/usr/bin/env /opt/local/bin/python2.5

(I made the change in the Portfile just to make sure)

MPI *stuff* are among the very few things I prefer to do myself (without
MacPorts, although the python's I add mpi4py to are MP versions), since it
allows me more flexibility.

You can also install the OpenMPI variant of mpi4py and avoid this issue
altogether.  I tend to use OpenMPI for my Macs, anyway (though I like mpich2
better for my Linux boxes, for no special reason, I get similar performance
out of both).

Happy tidings,
Jason

On Sat, Jan 8, 2011 at 1:02 AM, Jörg Frauendiener <
joerg.frauendiener at mac.com> wrote:

> I have recently come across a somewhat surprising issue:
> I installed py27-mpi4py which depends on mpich2 and python27. I was
> surprised to see that mpich2 itself depends on python25. Can someone explain
> to me why that should be the case? The same is true for py26-mpi4py.
>
> I have played around with the Portfile, replacing the references in mpich2
> to python25 with python27 and it installs perfectly. I have not done any
> other tests, though. So the question is: is this dependency on python25 a
> necessity or can it be replaced with python2[67]?
>
> Joerg
>
>
>
>
>   --
> Jorg Frauendiener         | Tel.: +64-3-479-7770
> Mathematics & Statistics  | Fax:  +64-3-479-8427
> University of Otago       | joergf at maths.otago.ac.nz
> P.O. Box 56               | jorg.frauendiener at otago.ac.nz
> Dunedin 9010              | http://www.maths.otago.ac.nz
> Skype: frauendiener
>
>
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-- 
Jason M. Swails
Quantum Theory Project,
University of Florida
Ph.D. Graduate Student
352-392-4032
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