[Scons-users] Clone effectiveness

[Bill Deegan]

Yes. That's generally how I go about it.
An Environment per type of build. Passed via SConscript's export argument
generally to all SConscripts but that my not make sense depending on your
build.
That way each SConscript could check if the env it's been passed is one it
"wants" to build.


On Fri, Sep 14, 2018 at 5:56 PM Hua Yanghao <huayanghao at gmail.com> wrote:

> I see. I solve this problem by defining and creating only new env for
> a build at top level, and never creating new env in SConscript.
> e.g. all SConscript is using a common pre-defined env, but one
> SConscript can be used by multiple env.
>
> This way my number of env is equal to the number of build target I have.
> On Fri, Sep 14, 2018 at 4:19 PM Gary Oberbrunner <garyo at oberbrunner.com>
> wrote:
> >
> > Overrides aren't expensive. Go ahead & use them, pass keyword flags to
> builders etc.
> > But let's say you have a sub-SConscript that must use a different
> compiler for everything in that subdir. Typical use is to import the main
> env, clone it, and modify for all the targets in that sub-SConscript.
> >
> > On Fri, Sep 14, 2018 at 9:41 AM Hua Yanghao <huayanghao at gmail.com>
> wrote:
> >>
> >> But seems passing flags also does similar thing with override?
> >>
> >> What must be changed in the env that cannot be done with ovrride? as
> >> majority of the builds are based on variable substitution.
> >> On Fri, Sep 14, 2018 at 3:12 PM Gary Oberbrunner <garyo at oberbrunner.com>
> wrote:
> >> >
> >> > Most people use them in a sub-SConscript so they can make changes to
> the env in that script that don't propate up to the calling SConstruct. Not
> the only use case of course, but a popular one.
> >> >
> >> > -- Gary
> >> >
> >> > On Fri, Sep 14, 2018 at 8:15 AM Hua Yanghao <huayanghao at gmail.com>
> wrote:
> >> >>
> >> >> Thanks Gary.
> >> >>
> >> >> In this case I think I am mostly using overrides, and only one env
> per
> >> >> software image build.
> >> >>
> >> >> If we have overrides what are the scenarios that a Clone() of the env
> >> >> is a must to have?
> >> >> On Fri, Sep 14, 2018 at 2:03 PM Gary Oberbrunner <
> garyo at oberbrunner.com> wrote:
> >> >> >
> >> >> > No. It may create an override internally, if you pass some keyword
> args, but that's not a clone. So you can call Object() thousands of times
> for sure.
> >> >> >
> >> >> > -- Gary
> >> >> >
> >> >> > On Fri, Sep 14, 2018 at 7:56 AM Hua Yanghao <huayanghao at gmail.com>
> wrote:
> >> >> >>
> >> >> >> Is every call to "Object()" implicitly creates a clone of
> environment?
> >> >> >> I seems like so just want to confirm.
> >> >> >> On Thu, Sep 13, 2018 at 9:20 PM Mats Wichmann <mats at wichmann.us>
> wrote:
> >> >> >> >
> >> >> >> > On 09/13/2018 12:52 PM, Damien Hocking wrote:
> >> >> >> > > We do this too.  Most dlls and sos have a cloned environment.
> >> >> >> >
> >> >> >> > As I said earlier, we clone lots (>90% of our sconscripts
> contain a
> >> >> >> > Clone() call), but the actual build time dwarfs the "process the
> >> >> >> > SConscripts" phase (*) so I don't worry much about it. We're
> not getting
> >> >> >> > killed on memory; I can build easily enough in a 2gb
> Vagrant-provisioned
> >> >> >> > (Linux) image. So while I'd like to *know* the numbers, it's
> mostly
> >> >> >> > curiosity.
> >> >> >> >
> >> >> >> > Maybe we can resurrect some of the benchmarking/timing code
> that exists
> >> >> >> > in the codebase now to get more info?
> >> >> >> >
> >> >> >> > * - recent build timings:
> >> >> >> > Total build time: 360.533189 seconds  (using scons -j4)
> >> >> >> > Total SConscript file execution time: 14.785102 seconds
> >> >> >> >
> >> >> >> > 15 seconds is slow, but if I sped up the sconscript time by
> 50%, I'd
> >> >> >> > still make no more than a 2% impact on the overall time.
> >> >> >> >
> >> >> >> > >> On Sep 13, 2018, at 12:27 PM, Pierre-Luc Boily <
> pierreluc.boily at gmail.com> wrote:
> >> >> >> > >>
> >> >> >> > >> Hello!
> >> >> >> > >>
> >> >> >> > >> Just read on the forum :
> >> >> >> > >>
> >> >> >> > >> /Here's the caveat.
> >> >> >> > >> Don't make a gazillion Clone's they're not lightweight.
> >> >> >> > >> If you make 100, it won't kill you, if you make 1000's you
> may start seeing
> >> >> >> > >> memory and speed impacted./
> >> >> >> > >>
> >> >> >> > >> Our project branch contains 800 sconscript files.  From
> those 800, 300 are
> >> >> >> > >> for windows compilation, 500 are for unix compilation.
> >> >> >> > >>
> >> >> >> > >> We systematically create a clone of the environment at the
> beginning of
> >> >> >> > >> *each *sconscript.  So, if I understand well, it might not
> be the best
> >> >> >> > >> approach.  It would be better to do a Clone only when it is
> needed?
> >> >> >> > >> Reducing the number of clone could potentially speed up the
> creating of the
> >> >> >> > >> tree?
> >> >> >> > >>
> >> >> >> > >> Thx
> >> >> >> > >>
> >> >> >> > >>
> >> >> >> > >>
> >> >> >> > >> --
> >> >> >> > >> Sent from:
> http://scons.1086193.n5.nabble.com/Users-f16930.html
> >> >> >> > >> _______________________________________________
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> >> >> >> >
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> >> >> >
> >> >> >
> >> >> > --
> >> >> > Gary
> >> >> > _______________________________________________
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> >> >
> >> >
> >> > --
> >> > Gary
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> >
> >
> > --
> > Gary
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