CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 08/16/2017 12:17 PM, Michael Bieri wrote:
> Hi all
>
> The CGAL documentation just says that I have to enable the parallel tag,
> like:
>
> typedef CGAL::Parallel_tag Concurrency_tag;
> typedef
> CGAL::Mesh_triangulation_3<Mesh_domain,CGAL::Default,Concurrency_tag>::type
> Tr;
>
> Surprisingly, it compiled right after that modification, even though I
> neither set any link flags for the Intel TBB nor did I find any traces
> that I already have Intel TBB on my system (Mac Book Pro) at all.

If you copy-paste a cmake script from CGAL it might be automatically
done. I know this a proposal to issue a warning when the user ask
for parallel support while it is not available but it was not
implemented IIRC. One way to check is to verify that
CGAL_LINKED_WITH_TBB is defined.
Otherwise have a look at this cmake script for example:
https://github.com/CGAL/cgal/blob/master/Mesh_3/examples/Mesh_3/CMakeLists.txt

> What exactly do I need to do to use parallel meshing? How can I control
> the number of threads? Is there an example?

You should refer to the Intel TBB documentation.
Something like this should work:

{
  tbb::task_scheduler_init tsi(6); // 6 threads
  run_parallel_algo1(); // Uses 6 threads
}

Sebastien.

> Thanks a lot and best regards,
> Michael