[Scons-users] Per target env variables

[Bill Deegan]

use --debug=count to help you know how many Environment()'s you're creating
(including via clone).
If the number is large and you're having performance problems, then it's
likely something worth looking at.
(large >1000 or maybe 10k).

-Bill

On Mon, Sep 10, 2018 at 4:54 PM Mats Wichmann <mats at wichmann.us> wrote:

> On 09/10/2018 08:40 AM, Hua Yanghao wrote:
> > Not sure how Object(CFLAGS = old + new) is handled, but I have
> > verified that definitely going to customize for each and every object,
> > and no clash seen.
> > If this, behind the scene is also using a Clone() somehow I starts to
> > understand why my build startup is a bit slow (totally acceptable
> > though, e.g. for a build that creates 22 different target, a few
> > hundred C files each), around 9 seconds before the first build prints
> > on screen.
>
> I've looked at the work done to clone, and it's a fair bit. I've got a
> project that does a lot of clones, and is slow to start up, but I'm far
> from convinced it's the cost of cloning that makes it so.  I'd suggest
> if startup time isn't bugging you, don't worry about it.  If startup
> time *is* bugging you, then clones are _one_ place to look.
>
>
> >> On Wed, Sep 05, 2018 at 11:57:38PM -0400, Bill Deegan wrote:
> >>> 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.
> >>
> ...
> >>
> >> But in this scheme we clone a lot.  Maybe this is too heavyweight?
> >>
> >> Regards,
> >> Petteri
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