[Nix-dev] Re: make -j<n> howto?

[Peter Simons]

Marc Weber writes:

 > Using -j x could lead to different builds (doesn't in most cases though).

Um, what exactly do you mean? Are you saying that nix doesn't utilize
multi-processor machines because there is some inherent design problem that
would lead to broken packages if multiple CPUs are being used during the
build?


 > The only way to do this is adding that option to the builder.sh file or
 > such. (default buildPhase)

Does anyone agree with me when I say that this situation is unsatisfactory?
I don't know about others, but I don't want to edit the package distribution
just to pass a -j8 flag to make. Frankly, I am rather baffled that such an
obvious use case isn't supported.


 > It would be interesting to have an experimental maybe unpure use numcores
 > environment option which would be 1 in all production cases (buildfarm)
 > but might be set to another value on your local developement machine.

What exactly makes a parallel build "unpure"? Are you referring to broken
makefiles that contain race conditions and thus fail when make executes
build jobs concurrently?

Peter