[Nix-dev] ‘NO_PARALLEL_BUILD’ and ‘NUM_CORES’ attributes

[Ludovic Courtès]

Hello,

Marc Weber <marco-oweber at gmx.de> writes:

> +
> +  NO_PARALLEL_BUILD_buildPhase = 1;
>  }
>
> Modified: nixpkgs/branches/stdenv-updates/pkgs/development/compilers/haxe/default.nix
> ===================================================================
> --- nixpkgs/branches/stdenv-updates/pkgs/development/compilers/haxe/default.nix	2010-06-15 19:00:54 UTC (rev 22284)
> +++ nixpkgs/branches/stdenv-updates/pkgs/development/compilers/haxe/default.nix	2010-06-15 19:00:58 UTC (rev 22285)
> @@ -55,6 +55,8 @@
>  
>        inherit zlib;
>  
> +      NUM_CORES = 1;

That’s intrusive and ugly to the eye.

Given Nix’ focus on deterministic builds, sequential builds should
remain the rule, not the exception.  That is, one would only annotate
packages known to be parallel-build-safe (i.e., the opposite of what
this patch does.)

Besides, parallel builds almost only matter when building things
locally.  The build farm is usually able to find other build tasks to
feed idle CPUs, anyway.

What’s more, ‘make -j’ builds interfere with the idea that ‘nix-worker’
has of the number of idle CPUs.

I’m in favor of reverting.

Thanks,
Ludo’.