[Scons-users] Need help to improve the incremental build time while using SCons

[Russel Winder]

On Tue, 2017-06-20 at 10:59 +0530, Basil Mathew wrote:
> 
[…]

> 
> I read that there are some improvements available in SCons version
> "2.5.1", I will try to set this up.

This is definitely a good first step. I can't remember exactly when
certain changes were made, but I suspect 2.4 → 2.5 will give a speed
up. But I am not sure it will solve the problem totally.

> In the mean while, I have these questions
> 
> 1. Is the nearly 6 fold increase in the incremental build time as
> compared
> to GMake on expected lines? I did go through the archive e-mails, but
> could
> not get a concrete answer to the question.

In a sense yes, Make uses only timestamps to determine whether
something needs to be rebuilt, whereas SCons uses timestamps and
signatures. Calculating the signatures has a cost but should lead to
fewer unnecessary builds. In effect SCons prioritises not building.
This does mean that SCons can pay a "no build" penalty.

Make is also fairly poor at this…

Tup and Ninja have very different approaches to build leading to an
almost zero time for "no build" situations. However they are not
intended (well Ninja isn't anyway) for manual use, they are intended as
backends for "meta-build" systems such as CMake, Meson, and Reggae. 

> 2. Are there any other options that would allow me to get a more
> favorable
> incremental build time?

All my experience is with relatively small builds, and rarely do I have
a "no build" situation. However, some people have used SCons with huge
codebases, and one person, Jason ??? <brain-fail-on-remembering-
names/>, developed a layer over SCons called Parts to manage these
sorts of issues. There is a (sort of) plan to merge Parts into SCons
but that hasn't happened yet.

-- 
Russel.
=============================================================================
Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder at ekiga.net
41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel at winder.org.uk
London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder
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