[OE-core] [PATCH] bison: Reset load average settings if specified in environment

[Khem Raj]

On Sun, Mar 15, 2020 at 3:14 PM Richard Purdie
<richard.purdie at linuxfoundation.org> wrote:
>
> On Sat, 2020-03-14 at 21:29 -0700, Khem Raj wrote:
> > In some cases, we run into parallel build failures where
> > BUILT_SOURCES
> > is skipped, as a result required header files are not generated and
> > the
> > build fails with missing header errors like
> >
> > ../bison-3.5.2/lib/uniwidth/width.c:21:10: fatal error: uniwidth.h:
> > No such file or directory
> >  #include "uniwidth.h"
> >           ^~~~~~~~~~~~
> > compilation terminated.
> >
> > BUILT_SOURCES should be built automatically with `make all` [1]
> > therefore
> > ensure that make is invoked with `all` target
> >
> > bison-native parallel build fails when -l<n> is passed globally from
> > build environment, errors like below due to race starts to show up
> >
> > Therefore removes a previous load limit if set
> >
> > [1]
> > https://www.gnu.org/software/automake/manual/html_node/Built-Sources-Example.html#Built-Sources-Example
>
> I'm not sure I understand this. We've seen a failure on our ubuntu1604
> performance tester which I think is the same bug as this. The
> environment on that machine doesn't change, so how/where is this -l
> option coming from?
>

>From custom distro global settings for EXTRA_OEMAKE

> I suspect there is some issue we're not quite getting to still :(
>
 its well reproducible now with -j and -l together on our builders, From what
I see in makefiles bison is doing right thing in using BUILT_SOURCES so
I suspect it could be make acting in a certain way when those options
are present.

our custom settings use -l options globally in EXTRA_OEMAKE
this is to let machines with certain configurations build when machines are
shared, we don't want a given build to use all resources on box. Yes one
could say why not do something else to limit the resources build uses but
this is a global setting that works well

This patch just ensures that any -l setting passed from environment is
cleaned up and reset. So for general case it will be a noop.

> Cheers,
>
> Richard
>