parallel NumPy: PyMPI, myMPI or something else?

Robert Kern robert.kern at
Tue Oct 23 02:57:08 CEST 2007

smithken04 at wrote:
> Robert,
> the answer could not have been shorter, but I got exactly the
> information I was looking for :-)
> Thank you so much!
> Just a single followup question:
>>> Or do I have to split each problem myself to make use of the
>>> parallelism?
>> Pretty much.
> Does "pretty much" imply that actually *some* parts of NumPy do make
> use of the parallel environment without any MPI handling from the
> user? I didn't find an indication for this during my short skimming
> over the NumPy documentation.

Sorry, that's really just American teenager idiom that's followed me into
adulthood; it means, roughly, "Yes, this is entirely, unequivocally true," much
like "Literally!" usually means "Figuratively!"

No part of numpy proper takes advantage of parallelism. Eric Jones has been
toying with using threads to split up some operations on large arrays between
cores on an SMP system, but it is not ready to merge into the trunk. The
performance numbers haven't been that good. The cost of thread locks is high.
But then, only one approach has been tried; if you are interested in trying
others, we'd be more than happy to help you along on the numpy-discussion
mailing list.

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth."
  -- Umberto Eco

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