[Cython] Cython 0.15rc2 and parallelization issue

[Francesc Alted]

Hi,

I'm trying to take advantage of the exciting new parallelizing
capabilities recently introduced in forthcoming 0.15 version, but I'm
having a small difficulty.  When I try to compile a small demo routing
(attached), I'm getting this error:

$ cython -a mandel.pyx

Error compiling Cython file:
------------------------------------------------------------
...
    for pix in prange(num_pixels, nogil=True, schedule="dynamic"):
        x = pix % width
        y = pix // width
        cr = begin_r + (x * span_r / (width + 1.0))
        ci = begin_i + (y * span_i / (height + 1.0))
        n = MandelbrotCalculate(cr, ci, maxiter)
                              ^
------------------------------------------------------------

mandel.pyx:50:31: Calling gil-requiring function not allowed without gil

While trying to figure out why MandelbrotCalculate does require GIL, I
replaced the "for  prange", by a trivial "for range", and the
annotated HTML source reveals that the only line in (light) yellow in
this function is

    return n

which is translated as:

  /* "mandel.pyx":22
 *         ti = 2*zr*zi + ci
 *         zr, zi = tr, ti
 *     return n             # <<<<<<<<<<<<<<
 *
 * @cython.boundscheck(False)
 */
  __pyx_r = __pyx_v_n;
  goto __pyx_L0;

  __pyx_r = 0;
  __pyx_L0:;
  __Pyx_RefNannyFinishContext();
  return __pyx_r;
}

My guess is that this __Pyx_RefNannyFinishContext() call is preventing
to call the routing from the parallel loop.  Is that a bug, a
limitation of current implementation or it is just that I'm missing
something?

Thanks,

-- 
Francesc Alted
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