bug#51787: GC takes more than 9 hours on berlin

[Mathieu Othacehe]

Hello,

On berlin, the daily GC command is still running whereas it was started
9 hours ago.

--8<---------------cut here---------------start------------->8---
guix processes
[...]
SessionPID: 37231
ClientPID: 37195
ClientCommand: 
/gnu/store/49vfv8l1j96bbd73ssbqanpnjz83arss-guix-1.3.0-11.014f1b6/libexec/guix/guile
 \ /gnu/store/49vfv8l1j96bbd73ssbqanpnjz83arss-guix-1.3.0-11.014f1b6/bin/guix 
gc -F10995116277760
--8<---------------cut here---------------end--------------->8---

and

--8<---------------cut here---------------start------------->8---
mathieu@berlin ~$ ps auxww|grep 37195
root      37195  0.0  0.0 183260 33440 ?        Sl   03:59   0:00 
/gnu/store/49vfv8l1j96bbd73ssbqanpnjz83arss-guix-1.3.0-11.014f1b6/libexec/guix/guile
 \ /gnu/store/49vfv8l1j96bbd73ssbqanpnjz83arss-guix-1.3.0-11.014f1b6/bin/guix 
gc -F10995116277760
--8<---------------cut here---------------end--------------->8---

That's really problematic as it is blocking some other berlin services
such as Cuirass, which has 4564 packages in its fetch queue:

--8<---------------cut here---------------start------------->8---
mathieu@berlin ~$ less /var/log/cuirass-remote-server.log
[...]
2021-11-12T12:47:01 period update: 0 resumable, 0 failed builds.
2021-11-12T12:47:01 period update: 4564 items in the fetch queue.
--8<---------------cut here---------------end--------------->8---

Thanks,

Mathieu