[Cython] CEP: prange for parallel loops

Dag Sverre Seljebotn d.s.seljebotn at astro.uio.no
Mon Apr 4 11:47:06 CEST 2011

On 04/04/2011 11:43 AM, Dag Sverre Seljebotn wrote:
> CEP up at http://wiki.cython.org/enhancements/prange
> """
> This spec is the result of a number of discussions at Cython workshop 
> 1. Quite a few different ways of expressing parallelism was looked at, 
> and finally we decided to split the problem in two:
>  * A simple and friendly solution that covers, perhaps, 80% of the 
> cases, based on simply replacing range with prange.
>  * Less friendly solutions for the remaining cases. These cases may 
> well not even require language support in Cython, or only in indirect 
> ways (e.g., cdef closures if normal closures are too expensive).
> This document focuses exclusively on the former solution and does not 
> intend to cover all use-cases for parallel programming, only the most 
> common ones.
> """
> Note that me and Mark talked some more on the way to the airport, and 
> also I got a couple of more ideas afterwards, so everybody interested 
> should probably take a read even if you were there for discussions.

To be more specific, here's the main post-workshop changes:

  * if cython.parallel.firstthreaditer()/lastthreaditer() # Use if-test 
in loop for thread setup/teardown

  * An idea for implementing threadnum() in a way so that we can drop 
the rather complex Context idea.

  * More thoughts on firstprivate/lastprivate

Dag Sverre

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