GitLab

Force a full GC after importing a project

Closes #59477

See merge request gitlab-org/gitlab-ce!26803

(cherry picked from commit 57cba4d1)

d4c6a3af Force a full GC after importing a project

Partially addresses #47424.

Because we don't need them, and they would slow down
the repository, keeping unneeded objects as well.

We could also consider doing this in regular housekeeping.

[ci skip]

This moves tracking of the pushes since the last Git GC from PostgreSQL
to Redis. This reduces the number of writes on the "projects" table.
This in turn reduces the vacuuming overhead.

The lease used for incrementing the counter has been removed. This lease
was mostly put in place to prevent high database load but this isn't
needed anymore due to the counter now being stored in Redis.

Fixes gitlab-org/gitlab-ce#22125

Due to a stale NFS cache, it's possible that a branch lookup fails
while `git gc` is running and causes missing branches in merge requests.

Possible workaround for #15392

This reverts commit 3e991230.

# Conflicts:
#	app/models/project.rb

Favor `unless` over `if` for negative conditions
(or control flow ||).

See #17478

This allows us to track how much time is spent in updating the
"pushes_since_gc" column as well as the time needed to obtain the lease.