[m-rev.] for review: Support dynamic creation of Mercury engines in low-level C parallel grades.

[Peter Wang]

On Wed, 25 Jun 2014 14:29:42 +1000, Paul Bone <paul at bone.id.au> wrote:
> > > > diff --git a/runtime/mercury_wrapper.h b/runtime/mercury_wrapper.h
> > > > index 4f7ce48..3a4a50c 100644
> > > > --- a/runtime/mercury_wrapper.h
> > > > +++ b/runtime/mercury_wrapper.h
> > > > @@ -258,7 +258,7 @@ extern MR_Unsigned          MR_contexts_per_thread;
> > > >  
> > > >  /*
> > > >  ** The number of outstanding contexts we can create
> > > > -** (MR_contexts_per_thread * MR_num_threads).
> > > > +** (MR_contexts_per_thread * MR_num_ws_engines).
> > > >  */
> > > >  extern MR_Unsigned          MR_max_outstanding_contexts;
> > > >  
> > > 
> > > That raises a question.  Are contexts created for thread.spawn_native
> > > counted towards this limit?
> > 
> > Yes, because it is a (crude) attempt to limit memory usage.
> 
> Okay, that's fair enough.  It should be in a comment somewhere, probably
> here though.

Oh, I see.  Exclusive contexts would eat into the number of contexts
that work-stealing engines can use, which is probably unexpected.
Rather, exclusive contexts should NOT count towards
MR_max_outstanding_contexts (and MR_max_outstanding_contexts and
MR_max_contexts_per_thread should be renamed).

Peter