Re: [PATCH v5 07/11] maintenance: take a lock on the objects directory

[Derrick Stolee <stolee@gmail.com>]

On 9/21/2020 9:36 AM, Ævar Arnfjörð Bjarmason wrote:
> There's now two different lock strategies in builtin/gc.c, the existing
> one introduced in 64a99eb476 ("gc: reject if another gc is running,
> unless --force is given", 2013-08-08) where we write the hostname to the
> gc.pid file, and then discard the lockfile depending on a heuristic of
> whether or not it's the same etc., and this one.
> 
> With this as an entry point we'll entirely do away with the old one
> since we don't use the "gc --auto" entry point.

Users could still erroneously launch two `git gc` commands concurrently
and that will not use the maintenance.lock file. The GC lock is worth
keeping around until we redirect the `gc` command to be an alias that
runs `git maintenance run --task=gc [options]`.

> All of that may or may not be desirable, but I think a description in
> the docs & tests for how these lock files should interact would be
> helpful. E.g. writing a different hostname in the gc lockfile and
> setting the time on it with with "test-tool chmtime" will cause it to
> plow ahead, but doing the same for "git maintenance" will stop it in its
> tracks no matter the time or content.

Thanks for the pointers to create this test. I'll try to get to it
soon. For now, here is a tracking issue [1].

[1] https://github.com/gitgitgadget/git/issues/737

Thanks,
-Stolee