From: Mike Hommey <mh@glandium.org>
Date: Thu, 16 Apr 2020 11:34:04 GMT
Subject: Re: Order of operations at the end of fast-import?
Message-ID: <20200416113404.pr2hzihavdvtfjh3@glandium.org>
In-Reply-To: <20200416042449.ztgyrdunsrzt7avp@glandium.org>

On Thu, Apr 16, 2020 at 01:24:49PM +0900, Mike Hommey wrote:
> Hi,
> 
> I just noticed that the order of operations at the end of fast-import
> are:
> - end_packfile
> - dump_branches
> - dump_tags
> 
> The first may create loose objects if the pack is small (per
> fastimport.unpackLimit, defaulting to 100). The latter two create refs.
> 
> There seems to be a theoretical race condition here, if something else
> triggers a gc at the "wrong" time, the loose objects might be cleaned up
> and the branches/tags refs become dangling.

Come to think of it, this is only a problem with --prune=now, and the
same applies to loose objects created with git add, git write-tree,
git-commit-tree.

Mike