Out of memory on package installation

[Zert]

Sometimes on nix-env -i pkgname I have such error:

  error: unable to fork: Cannot allocate memory

There is 1Gb RAM on VirtualBox instance. Is 1Gb memory amount not enough for nix? Any plans to reduce a memory consumption?

[vcunat]

The evaluation can be expensive, especially for nix-env without -A, as it has to evaluate all packages and check their names.

[Zert]

NixOS now has about 3500 packages, while Gentoo has about 20000. So, when NixOS will have such amount of packages, will it consume 6 GB memory?

[7c6f434c]

No, everyone will just use -iA from the very beginning…

[domenkozar]

NixOS has ~14k packages. And yes, it's memory intensive. As said, we're aiming for -iA to be preferred way of installing software.

[Zert]

What is destiny of such functionality if nobody uses it? First you made evaluation of all packages, then you do not use it. Nice 😎

[7c6f434c]

Currently the package attribute names slowly converge to their package names; initially Nix language didn't allow attributes named foo-bar

[edolstra]

You can tell Nix to garbage-collect more aggressively:

GC_INITIAL_HEAP_SIZE=128k nix-env -qa

With this, nix-env -qa takes 235 MB on my laptop. (Without it, 471 MB.)

You can also do:

echo 1 > /proc/sys/vm/overcommit_memory

That should make the fork error go away.

[Zert]

@edolstra GC_INITIAL_HEAP_SIZE=128k had no effect, but echo 1 > /proc/sys/vm/overcommit_memory works fine. Thank you!

[jagajaga]

I think we should close this issue or wait when nix won't use such amount of memory.

[jagajaga]

Because I have the same problem on 1GB of memory.

[akavel]

As a note for future readers: this happended for me on Hyper-V too, and the suggested overcommit_memory tweak fixed it for me. I assume a change like below in /etc/nixos/configuration.nix should have the same effect:

boot.kernel.sysctl."vm.overcommit_memory" = "1";