Re: parallel build issues

[Nick Bowler]

On 2021-06-21, Werner LEMBERG <wl@gnu.org> wrote:
>
>> The problem is not related to the snippet you posted.  The
>> concurrent recursive make invocations are being spawned from
>> somewhere else in your build system.
>
> The `Makefile.am` file one level higher is as follows.
>
>   ACLOCAL_AMFLAGS = -I gnulib/m4 -I m4
>
>   SUBDIRS = gnulib/src \
>             lib \
>             frontend \
>             doc
>   EXTRA_DIST = bootstrap \
>                bootstrap.conf \
>                FTL.TXT \
>                gnulib/m4/gnulib-cache.m4 \
>                GPLv2.TXT \
>                README \
>                TODO \
>                .version
>
>   BUILT_SOURCES = .version
>   .version:
>         echo $(VERSION) > $@-t && mv $@-t $@
>
>   dist-hook:
>         echo $(VERSION) > $(distdir)/VERSION.TXT
>
> Looks pretty standard to me, but maybe I'm wrong.

Nothing shown here is going to cause this problem.  But with recursive
build problems it is insufficient to just look at just one makefile:
the problematic make invocations could be coming from anywhere in your
project.

For example, perhaps you have the same "frontend" directory listed also
in SUBDIRS for some other unrelated makefile?  That is probably the
simplest way this situation could happen.

Or perhaps the parent directory's makefile was itself being processed
by concurrent recursive invocations, which then results in independent
recursive invocations in the subdirectories.

If you can't find anything by a code inspection GNU make has some debug
features which may help visualize what is going on.

Cheers,
  Nick