Re: "lock file exists" when fetching in bare clone of repository

From: Jeff King <peff@peff.net>
Date: Aug 26, 2025, 11:19 UTC
Message-ID: <20250826111952.GA1926324@coredump.intra.peff.net>
In-Reply-To: <20250820213323.GA1667633@coredump.intra.peff.net>

On Wed, Aug 20, 2025 at 05:33:23PM -0400, Jeff King wrote:

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> If so, and assuming you're on a case-insensitive filesystem, then the
> lock files would collide. You wouldn't see anything after the fact
> because git-fetch itself would create the colliding lockfile, and then
> clean it up after hitting the fatal error.
> 
> If that is the case, you can try using the reftables backend in v2.51.0.
> It doesn't use the filesystem for its ref storage or locking. Something
> like:
> 
>   git init --bare --ref-format=reftable

The response below came to me off-list. Here it is quoted with my reply:

On Sun, Aug 24, 2025 at 05:03:20PM +0100, Dave Evans wrote:

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> I'm sorry but I do not have an email client I could use to post to the
> git mailing list.
> Please could you post my thoughts on this to the list.
>
> https://lore.kernel.org/git/20250820213323.GA1667633@coredump.intra.peff.net/
>
> I use git 2.51.0 built using Macports on a very old version of macOS
>
> There are a couple of repos on github that were showing this problem:
> vectorgraphics/asymptote
> ghc/ghc
>
> Both of them were bare clones.
>
> I applied  --ref-format=reftable to the vectorgraphics/asymptote repo
> and a fetch
> went through to the end successfully
>
> The only snag I can see is that cgit no longer works. It says :
> Failed to open github/vectorgraphics/asymptote: No such file or directory
>
> The version of cgit is about 5 years old

I think that's all expected. Unlike most systems which call Git commands like for-each-ref, etc, to access the ref store, cgit is linked directly against Git's C code (something we don't support, but the cgit authors accepted as a risk). So an old version of cgit will link against an old version of Git, and won't know about reftable at all.

It _might_ not even be able to detect the directory as a git repo, though I thought the reftable format was designed to let even old versions of Git see the repo (e.g., the dummy value in HEAD).

-Peff