Re: Adding threading support to lang/sbcl

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

> Date: Wed, 14 Aug 2024 16:28:06 +0000 (UTC)
> From: Kevin Bloom <ktnb%netbsd.org@localhost>
> 
> I've found an issue with our current build of lang/sbcl in which it
> isn't compiled with threading support. This means that if you attempt
> to use the bordeaux-threads[1] library it won't work. I've tested it
> locally and it appears to work as expected useing the attached patch.
> 
> Does anyone know of a reason why this wasn't added before or have any
> reason why I shouldn't add it? I don't really see the need for making
> an option for it as it doesn't change much of anything from a
> packaging point of view.

I think the main question is whether it is stable enough to deploy.

On the one hand, this is hard to ascertain for sure -- ideally SBCL
would have some stress tests to exercise various kinds of plausible
races.

On the other hand, nobody wrote down the details of any instability
from past experiments.  So maybe it was an oversight.

I'd suggest flipping it on and running the SBCL test suite -- and, if
there's no tests that specifically exercise threads in it, try some
small experiments with threads that do lots of memory allocation to
exercise the GC and do some coordination (mutexes, condvars, threaded
queues, whatever).