Re: devel/py-joblib patch

[Jason Bacon <jtocino%gmx.com@localhost>]

On 1/10/24 20:40, Taylor R Campbell wrote:
> OK, but for NetBSD today, why is running `sysctl hw.ncpu' in a
> subprocess better than calling os.sysconf('SC_NPROCESSORS_CONF')?

It's not, but this is a temporary fix, so I just followed the pattern
for other platforms.  It will be changed to the number of physical cores
once that's possible, which will require a sysctl, unless a non-standard
sysconf variable is added.

This routine should be called infrequently (ideally once per process),
so performance is not a major concern anyway.

> They are always the same, because sysconf(_SC_NPROCESSORS_CONF) in
> libc just queries hw.ncpu (but with substantially less overhead than
> running a subprocess).
>
> Maybe tomorrow we'll add hw.ncoresnotcountingthreads or whatever, but
> I'm confused why you say you have to stick with subprocesses and not
> os.sysconf for now.

Did you see Martin's suggestion to expose the low-level kernel data
rather the compute core counts?  I think this is a good approach, as it
minimizes complexity in the OS, and maximizes flexibility for the user,
albeit with a small amount of work.