[Scons-users] Scons none-deterministic behavior for incremental build

[Bill Deegan]

Generated by logic in your sconstruct/sconscripts? or do you shell out and
run a script/program to generate it.


On Tue, Dec 4, 2018 at 4:37 PM Hua Yanghao <huayanghao at gmail.com> wrote:

> Hi Bill,
> config.h is generated file, not checked in, it is generated in the
> build folder only.
> Well at least I see scons is very odering-sensitive. For example, if
> the order of SConscript processing changes (in the case of a set()),
> even if there is no dependency actually changed, scons thinks the
> target need to be rebuilt.
>
> any progress on these similar issues already? :)
>
> Best Regards,
> Yanghao
> On Tue, Dec 4, 2018 at 10:15 PM Bill Deegan <bill at baddogconsulting.com>
> wrote:
> >
> > Is "build/configs/qemu_arm_vexpress/arm3/config/config.h" a generated
> file? Or checked in?
> >
> > It's very unlikely to be set ordering. set's should only be used for
> membership checks not iteration in the SCons codebase.
> >
> > We're actively debugging similar issue.
> >
> > -Bill
> >
> > On Tue, Dec 4, 2018 at 3:23 PM Hua Yanghao <huayanghao at gmail.com> wrote:
> >>
> >> I does that a lot ... but a quick try to make sure no
> >> LIBS/LIBPATH/CPPPATH etc. is touched after Object() is being called,
> >> still shows the same 50~70% rebuild of the entire project.
> >> I am not using any parallel build, and somehow scons is having a very
> >> none-deterministic behavior.
> >>
> >> Actually I fixed partially the issue (e.g. in simpler build the
> >> incremental builds now works fine), due to python set() is having a
> >> random order for every run. I am thinking maybe scons is somehow also
> >> depends on the ordering of a set()? And when it happens to be the same
> >> order then no rebuild?
> >> On Tue, Dec 4, 2018 at 9:00 PM Oscar Anson <oscar at solidangle.com>
> wrote:
> >> >
> >> > Hi,
> >> >
> >> > Not sure if this could be related, but a similar issue happened to me
> where I get a relink of a shared library without changing anything in the
> project. It happened that I was setting the environment LIBS and LIBPATH
> after calling the builder of the library.
> >> >
> >> > El mar., 4 dic. 2018 20:55, Hua Yanghao <huayanghao at gmail.com>
> escribió:
> >> >>
> >> >> Dear Scons Experts,
> >> >> I recently hit on a very strange problem where scons incremental
> >> >> builds sometimes OK, sometimes the entire project is re-built.
> >> >>
> >> >> scons: 3.0.1
> >> >> python: 3.6.7
> >> >>
> >> >> --debug=explain gives below example trace:
> >> >> scons: rebuilding
> >> >> `build/configs/qemu_arm_vexpress/arm3/config/config.h' because
> >> >> AlwaysBuild() is specified
> >> >> __CONFIG build/configs/qemu_arm_vexpress/arm3/config/config.h
> >> >> scons: rebuilding
> >> >>
> `build/configs/qemu_arm_vexpress/arm3/firmware/arch/armv7/arch_init.o'
> >> >> because:
> >> >>            `firmware/arch/armv7/arch_init.c' is no longer a
> dependency
> >> >>            `firmware/arch/armv7/arch_init.c' is a new dependency
> >> >>
> >> >> It seems some how the C file itself is removed and re-added as the
> >> >> Object() dependency, and causes rebuild. However this is *NOT*
> >> >> *always* the case. Sometime the rebuild doesn't happen.
> >> >>
> >> >> I failed to create a minimal example that can show this issue so far,
> >> >> but in the production environment it is about 50% full-rebuild and
> 50%
> >> >> incremental re-build.
> >> >>
> >> >> Any thoughts or hints?
> >> >>
> >> >> Thanks,
> >> >> Yanghao
> >> >> _______________________________________________
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> >> >
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