From: Brandon Casey <casey@nrlssc.navy.mil>
Date: Wed, 10 Oct 2007 22:55:25 GMT
Subject: Re: Spam: Re: git branch performance problem?
Message-ID: <470D585D.1030808@nrlssc.navy.mil>
In-Reply-To: <8c5c35580710101445h232f9a67jd0c326b3b97ae3dd@mail.gmail.com>

Lars Hjemli wrote:
> On 10/10/07, J. Bruce Fields <bfields@fieldses.org> wrote:
>> On Wed, Oct 10, 2007 at 06:30:02PM -0300, Han-Wen Nienhuys wrote:
>>> could it be that GC does not handle cyclic alternates correctly?
>> Does it handle alternates at all?  If you run git-gc on a repository
>> which other repositories get objects from, then my impression was that
>> bad things happen.
>>
> 
> AFAIK 'git gc' is safe, while 'git gc --prune' will remove loose
> (unreferenced) objects.

No, this is not the case, unless something has changed very recently
in git-gc or git-repack. Even git-gc with no arguments is unsafe if
the repository being gc'ed is listed in another's alternates.

git-gc calls repack with -a and -d. which causes a new pack to be
created which only contains the objects required by the local repository.
The other packs are then deleted. Objects contained in those packs and
required by a "sharing" repository (one using the alternates mechanism)
will be deleted if the local repository no longer references them.

Maybe git-gc should make use of repack's new -A option by default and
only use -a (and not -A) when --prune is specified...

-brandon