Using "localhost" as a remote builder deadlocks the build

[LisannaAtHome]

A nix-build command of the form nix-build --builders "ssh://nix@localhost" will deadlock, because the local nix-build command is holding the /nix/store lock for that output, thus preventing the remote build process (running on the same machine) from grabbing the lock and performing the build. So the command gets stuck at "waiting for locks or build slots..."

[shlevy]

I'm not completely sure the answer here shouldn't just be "don't do that". @edolstra ?

[copumpkin]

It seems like it should be to have the tool tell you "don't do that" when you try it, rather than observing the deadlock, googling it, and seeing @shlevy tell you not to do that 😄

[LisannaAtHome]

this is desired as a workaround for #2012

If the resolution of this ends up being "don't do that", what's the right solution for #2012 ?

[shlevy]

Oh, right, fair.

[jwiegley]

Any word on this issue? Being able to specify localhost as a remote builder would make it much easier to prioritize local over remote builds across multiple machines (or vice versa, depending on the relative strengths of the machines, and the cost of networking).

[stale]

I marked this as stale due to inactivity. → More info

[stale]

I closed this issue due to inactivity. → More info

[Misterio77]

Has anyone ever found a workaround for this? I'd like to have a weaker machine help a stronger one with builds.

Configuring daemon or local (with protocol = null) as a buildMachine outputs the dreaded:

waiting for lock on '/nix/store/xxx'

Trying localhost (with protocol = ssh and a dedicated builder sshUser) freezes with:

building xxx on ssh://builder@localhost: debug1: Sending command: nix-store --serve --write

Is there any other way to set speedFactor on the local machine?

[maralorn]

I encountered the same issue. It would be really cool to be able to use remote builds but still prioritizing local builds.