Am Mittwoch, dem 13.07.2022 um 19:21 +0200 schrieb Julien Lepiller: > I've heard that theory before. From observation on my late armhf > server > (two cores): > > - it takes just below 2GB to build one of the derivations > - It doesn't swap a single byte > - whether with two or a single core, it takes roughly the same amount > of memory > - substitution is nice, it doesn't require lots of memory (and then - > - > cores is useless) > > I think it's because we load all the files in a batch before we build > them. The biggest amount of memory required is not for running the > compiler on a thread, but for loading files and keeping them in > memory for the whole duration of the build. With more threads, we > still don't load each file more than once (twice to build it), so > there's no reason it should take more memory. > > Or maybe the process of loading and building is inherently single- > threaded? I don't think so, but maybe? Loading and building is implemented in build-aux/compile-all.scm, which does use multiple parallel workers. However, since all compilation appears to be done in the same Guile process, I don't think multi- threading makes too big of an impact (it'll be the same garbage collector regardless of ordering).
Cheers
