Am Samstag, 15. Dezember 2012 schrieb Ludovic Courtès:
> First, guix-daemon is running as root, right?

Yes, in a separate terminal as
   NIX_SUBSTITUTERS="" guix-daemon --build-users-group=nixbld

> That seems to suggest that there’s a lock on each of these.  What does
> ‘ls -l /nix/var/nix/userpool/’ report?

-rw------- 1 root root 0 Dez 10 23:30 30001

/etc/group contains a line
nixbld:!:30000:nixbld1,nixbld2,nixbld3,nixbld4,nixbld5,nixbld6,nixbld7,nixbld8,nixbld9,nixbld10

and /etc/passwd:
nixbld1:x:30001:65534:Nix build user 1:/var/empty:/noshell
...
nixbld10:x:30001:65534:Nix build user 10:/var/empty:/noshell

> Can you also try running guix-daemon in strace, and then check then
> fcntl(fd, F_SETLKW, _) calls for user locks?

I find none of these:
   strace ./pre-inst-env guix-build hello 2>&1 | grep fcntl | grep F_SETLKW
returns nothing.

Andreas