Re: Question: How to execute git-gc correctly on the git server

From: Michal Suchánek <msuchanek@suse.de>
Date: Dec 9, 2022, 00:49 UTC
Message-ID: <20221209004918.GI28810@kitsune.suse.cz>
In-Reply-To: <Y5GLsZgmrxbBtLqo@coredump.intra.peff.net>

On Thu, Dec 08, 2022 at 02:01:05AM -0500, Jeff King wrote:

Show 15 quoted lines

> On Thu, Dec 08, 2022 at 02:16:31AM +0100, Michal Suchánek wrote:
> 
> > > A "git gc" on a "live" repo is always racy in theory, but the odds that
> > > you'll run into data corrupting trouble tends to approach zero as you
> > > increase the gc.pruneExpire setting, with the default 2 weeks being more
> > > than enough for even the most paranoid user.
> > 
> > And that two weeks expiration applies to what, exactly?
> > 
> > For commits there is author date and commit date but many other objecs
> > won't have these I suppose. And the date when the object is pushed into
> > the repository is unrelated to these two, anyway.
> 
> In this case it's the mtime on the object file (or the pack containing
> it). But yes, it is far from a complete race-free solution.

So if you are pushing a branch that happens to reuse commits or other objects from an earlier branh that might have been collected ín the meantime you are basically doomed.

How likely that is depends a lot on your workflow.

People deleting a branch and then pushing another variant in which many objects are the same is a risk.

People exporting files from somewhere and adding them to the repo which are bit-identical when independently exported by multiple people and sometimes deleting branches is a risk.

...

Thanks

Michal