[Nix-dev] Re: Another approach at parallelizing in-build jobs

[Nicolas Pierron]

Hi,

On Sun, Jun 20, 2010 at 22:23, Jeff Johnson <n3npq at mac.com> wrote:
>
> On Jun 20, 2010, at 4:02 PM, Peter Simons wrote:
>
>>
>> In other words, should a glibc that's been built with -j1 have a store
>> path different from one that's been built with -j2?
>>
>
> Since every build has different store path, does your question even make sense?

The output path hash is computed before the first step of the
compilation by combining all its dependencies and it build script and
other stuff used to define the build process.  The hidden question
that is asked here is should we consider -j options as a build
modifier or as a no-op option, in other words should we consider it in
the hash computation?

IMO, this depends on our ability at tagging builds with it.  So we
should probably have both method like:
* safe -j* builds in which case this is considered as a no-op.
(unlikely packages made with more than one make instances)
* unsafe -j* builds in which case this is considered as an unsafe operation.

The unsafe build could be used as a fallback if the safe build is not
provided by any other repositories or manifest.

-- 
Nicolas Pierron
http://www.linkedin.com/in/nicolasbpierron - http://nbp.name/