[Cython] OpenMP support

[Greg Ewing]

Stefan Behnel wrote:

> You *can* use Python references inside of nogil blocks, even if there's 
> a lot of stuff that you can't do with them, ... But you can access cdef 
 > attributes on them,

Strictly speaking it's not even safe to do that, unless
you know there's some locking mechanism in effect that
prevents the underlying Python object going away from
under you.

-- 
Greg