Re: bash parallel build: make[1]: warning: -j16 forced in submake: resetting jobserver mode.

[Cedric Blancher]

On Sun, 14 Apr 2024 at 01:24, Dmitry Goncharov <dgoncharov@users.sf.net> wrote:
>
> On Sat, Apr 13, 2024 at 12:41 AM Cedric Blancher
> <cedric.blancher@gmail.com> wrote:
> >
> > Good morning!
> >
> > Building bash HEAD on Cygwin 3.5.3 and Debian Linux 11  in make
> > parallel mode issues a warning, which looks like a Makefile bug:
> > $ make -h 16
> > ...
> > make[1]: warning: -j16 forced in submake: resetting jobserver mode.
> > ...
> > Can this be fixed please?
>
>
> It takes a certain makefile setting to cause this warning.
> E.g. -j16 can be specified in the makefile on the recipe line like this
>
> $ ls
> lib  makefile
> $ cat makefile
> all:; $(MAKE) -C lib -j4
> $ cat lib/makefile
> all:;
> $ make -j2
> make -C lib -j4
> make[1]: warning: -j4 forced in submake: resetting jobserver mode.
> make[1]: Entering directory
> '/home/dgoncharov/src/gmake/test/jobserver_reset/lib'
> make[1]: 'all' is up to date.
> make[1]: Leaving directory 
> '/home/dgoncharov/src/gmake/test/jobserver_reset/lib'
> $
>
> Submake detects that it has its own -j switch and it no longer
> participates in the parent make job server.
> Instead, the submake will become a master of its own jobserver and run
> up to 4 (in this example) jobs, and the parent make keep running its
> own job server with up to 2 (in this example) jobs.
> This can also be caused by settings in submake env.
> See https://www.gnu.org/software/make/manual/html_node/Error-Messages.html.
>
> You can check what env the submake in question has and which recipe
> runs it and see where this setting comes from.

We were only using
make -j16 all
at the bash base dir. That should NOT trigger this warning.

Ced
-- 
Cedric Blancher <cedric.blancher@gmail.com>
[https://plus.google.com/u/0/+CedricBlancher/]
Institute Pasteur