From: Shawn Pearce <spearce@spearce.org>
Date: Mon, 10 Oct 2011 23:49:12 GMT
Subject: Re: Garbage collection creates many unpacked objects.
Message-ID: <CAJo=hJtGyaudyL63AcaG=y4fvfO8Ka3pn=Orta-imb6AUXO6XA@mail.gmail.com>
In-Reply-To: <201110101730.43302.mfick@codeaurora.org>

On Mon, Oct 10, 2011 at 16:30, Martin Fick <mfick@codeaurora.org> wrote:
> If I clone linus' kernel, delete all the tags, and then run
> git gc, it ends up expanding into about 5K of unpacked
> objects.  The .git size goes from 473M to 511M.  This seems
> a bit strange no?  Shouldn't gcing yield a smaller repo an
> fewer unpacked refs?
>
> If I do this on our internal kernel repo (which has 2Ktags),
> it gets much more pathological, it expands to about 1M
> objects and grows to about 7G!!!

This is caused by unreachable objects being evicted from packs and
stored as loose objects for up to 2 weeks, until the next `git prune`
run. I think you can avoid this by using `git repack -a -d` instead of
`git gc`, but at the risk that a concurrent modification of the
repository may result in corruption due to a race condition between
the object being needed, and the object being deleted.