Nix tests can't run in a system with 512MiB of RAM

[viric]

Even having 100MiB of swap, the tests fail due to not being able to run 'xz -9' in corepkgs/nar.nix

# xz -9 > /dev/null 
xz: (stdin): Cannot allocate memory
# free
             total       used       free     shared    buffers     cached
Mem:        448744     265720     183024          0      23812     193500
-/+ buffers/cache:      48408     400336
Swap:       102396      50244      52152

As for nixpkgs, it makes the building of nix fail.

[viric]

'xz' alone runs fine.

[edolstra]

Yes, "xz -9" uses a lot of memory. Maybe add more swap?

[viric]

Well, we all know that solution :) My concern was more about it being a big requirement, for the package manager tests.
Of all NixOS pieces, only nix (its tests) requires that amount of memory.

[viric]

My solution has been, both in the raspberry pi and the sheevaplug, to use:

nixpkgs.config.packageOverrides = p: {
      nix = p.lib.overrideDerivation p.nix (attrs: {
        patchPhase = "sed -i s/-9// corepkgs/nar.nix";
        });
      nixUnstable = p.lib.overrideDerivation p.nixUnstable (attrs: {
        patchPhase = "sed -i s/-9// corepkgs/nar.nix";
        });
  };
}

[bjornfor]

+1 for reducing the memory footprint. (Why does a test need to use more memory than the actual system?)

Interesting, "man xz" actually has lots of info about memory usage and ways to limit it. Search for memory or memlimit.

[edolstra]

But the "actual system" does use this much memory because it (nix-push) calls "xz -9".