[m-rev.] for review: disable concurrency in non .par LLDS grades

[Peter Wang]

On Thu, 21 Aug 2025 13:05:54 +1000 Julien Fischer <jfischer at opturion.com> wrote:
> For review by Peter.
> 
> -----------------------------------------------
> 
> Disable concurrency in non .par LLDS grades.
> 
> The non .par LLDS grades currently "support" concurrency. However, this support
> is really on usable with a small few benchmark programs, due to the inability
> of the implementation to switch threads if the executing thread blocks. Disable
> this capability by causing spawn/3 to abort if used in non .par LLDS grades.
> 
> library/thread.m:
>     Make the above change to spawn/3.
> 
> compiler/globals.m:
>     Update the code that checks if the current grade supports concurrency.

Mention it in NEWS.

The help text for --parallel might need to be updated.

That should be fine, but there may be other documentation to update.

Peter