Re: [RFC] build with OpenMP by default?

[Mike Miller]

On Wed, Apr 23, 2014 at 3:49 AM, Susi Lehtola wrote:
> Still, talking about enabling OpenMP without anything in Octave that
> actually uses OpenMP is pretty much senseless... First one would have
> to implement parallellism, then test it and then talk about enabling it
> as a default.

If you didn't glance at the motivating bug report, here's a motivating
example that shows why I brought up enabling OpenMP by default:

  octave:1> im = imread ("large_image.tif");
  octave:2> clear -f
  octave:3> system ("pwd");
  /home/mike
  panic: Segmentation fault -- stopping myself...
  attempting to save variables to 'octave-workspace'...
  save to 'octave-workspace' complete

Enabling OpenMP in Octave, whether or not Octave itself uses it,
enables using OpenMP in oct-files. Without it, oct-files that do use
OpenMP (or use OpenMP-enabled libraries) can crash Octave. This
problem exists in 3.8.1 now, the GraphicsMagick library uses OpenMP.

I've just opened https://savannah.gnu.org/bugs/?42176, for which my
fix will be to enable OpenMP by default as I proposed in this thread.
Please comment there if you have thoughts on how to solve this problem
without linking Octave with OpenMP by default.

-- 
mike