Re: Allow parallelism in input/regression/lilypond-book/ (issue 547680043 by address@hidden)

[Han-Wen Nienhuys]

On Sun, Feb 23, 2020 at 2:59 PM Dan Eble <address@hidden> wrote:
>
> On Feb 23, 2020, at 06:08, Han-Wen Nienhuys <address@hidden> wrote:
> > I think we should do both: the lilypond runs in lp-book should be
> > protected by some sort of lock, and we should use both CPU_COUNT=M and
> > -jN.
> >
> > then worst case, you have M lilypond processes and N-1 other jobs.
>
> What would you recommend to a developer who doesn't want to run more than J = 
> M + N - 1 concurrent jobs due to lilypond development?  What values of M and 
> N would serve best?

Normally M=N= #cpus should be OK. A bit of extra parallelism doesn't
hurt, especially if you have hyperthreaded CPUs.

> > So wouldn't it appear that the way to exploit parallelism with
> > lilypond-book, short of writing its own jobserver, is to use CPU_COUNT
> > like we did before?
>
> Making lilypond-book a client of the GNU make job server sounds like an 
> option.
>
>   "Sharing Job Slots with GNU make"
>   https://www.gnu.org/software/make/manual/html_node/Job-Slots.html

This looks hairy, because it's not lilypond-book but lilypond itself
that starts up the jobs, so you have plumb through the jobserver
support.

-- 
Han-Wen Nienhuys - address@hidden - http://www.xs4all.nl/~hanwen