bug#69596: ‘guix publish’ memory leak

["Ludovic Courtès" <ludo@gnu.org>]

It seems that ‘guix publish’ has been leaking memory noticeably I’d say
since the beginning of the year on berlin.  After roughly 10 days, it
has several GiB resident and needs to be restarted or it becomes too
unresponsive.

I wonder what could be causing this because we used to let it run for
months without problems I believe.

This is what’s currently running on berlin:

  /gnu/store/cpnshv80n3mar5lwp4qqa2dxxxv4zb03-guix-1.4.0-16.aeb4943/libexec/guix/guile \
  /gnu/store/cpnshv80n3mar5lwp4qqa2dxxxv4zb03-guix-1.4.0-16.aeb4943/bin/guix \
  publish -u guix-publish -p 3000 -C lzip:9 -C zstd:19 --nar-path=nar \
  --listen=localhost --workers=8 --ttl=15552000s \
  --cache=/var/cache/guix/publish --cache-bypass-threshold=157286400

… coming from commit 21e4d6cd6913eca131f2c0fd0cd509fc843c7eb8.

I don’t see anything that changed recently, be it in maintenance.git
(for the parameters), ‘guix publish’, guile-{lzlib,zstd}, or Guile.
Maybe we had just been lucky?  Anyone else seeing this?

Ludo’.