[Cython] OpenMP support

[Francesc Alted]

A Tuesday 08 March 2011 18:50:15 Stefan Behnel escrigué:
> mark florisson, 08.03.2011 18:00:
> > What I meant was that the
> > wrapper returned by the decorator would have to call the closure
> > for every iteration, which introduces function call overhead.
> >
> >[...]
> >
> > I guess we just have to establish what we want to do: do we
> > want to support code with Python objects (and exceptions etc), or
> > just C code written in Cython?
> 
> I like the approach that Sturla mentioned: using closures to
> implement worker threads. I think that's very pythonic. You could do
> something like this, for example:
> 
>      def worker():
>          for item in queue:
>              with nogil:
>                  do_stuff(item)
> 
>      queue.extend(work_items)
>      start_threads(worker, count)
> 
> Note that the queue is only needed to tell the thread what to work
> on. A lot of things can be shared over the closure. So the queue may
> not even be required in many cases.

I like this approach too.  I suppose that you will need to annotate the 
items so that they are not Python objects, no?  Something like:

     def worker():
         cdef int item  # tell that item is not a Python object!
         for item in queue:
             with nogil:
                 do_stuff(item)

     queue.extend(work_items)
     start_threads(worker, count)


-- 
Francesc Alted