Re: Use $(MAKE) instead of 'make' in lilypond-book regtests (issue 569400043 by address@hidden)

[Han-Wen Nienhuys]

On Sun, Feb 23, 2020 at 12:29 AM <address@hidden> wrote:
>
> On 2020/02/22 23:18:43, hanwenn wrote:
> > On 2020/02/22 23:17:50, hanwenn wrote:
> > > you were already potentially in a state where you have 3 jobs each
> spawning 3
> > > lp-book invocations,
> >
> > whoops, I mean: 3 lp-book invocations spawning 3 lilypond subprocesses
> each, for
> > 9 in total.
>
> Considering that I build with CPU_COUNT=9 make -j9 I am pretty sure that
> I'd have noticed if that were happening so far.  I may have a nice
> number of cores (4) and memory considered plentiful (16GB) for a laptop,
> but 81 parallel instances of LilyPond would certainly bring this system
> to its knees.

In practice, this doesn't happen, because our build system doesn't
parallelize all that well, and we don't have much large lp-book
documents anyway

In particular, we do

define make_subdirs
#       enforce order to avoid surprises due to implicit dependencies
[ "$(1)" = "$(filter $(1),$(SUBDIRS))" ] || (echo "*** {$(1)} is not a
subset of ordered set {$(SUBDIRS)}" 1>&2 && false)
+$(foreach d, $(1), $(MAKE) -C $(d) $(2) &&) true

ie. we only recurse into one subdirectory at a time.

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