Re: [PATCH 0/2] Fix locking issues with git fetch --multiple --jobs=<n> and fetch.writeCommitGraph

From: Jeff King <peff@peff.net>
Date: Nov 4, 2019, 19:59 UTC
Message-ID: <20191104195928.GC20900@sigill.intra.peff.net>
In-Reply-To: <pull.443.git.1572740518.gitgitgadget@gmail.com>

On Sun, Nov 03, 2019 at 12:21:55AM +0000, Johannes Schindelin via GitGitGadget wrote:

Show 11 quoted lines

> The git fetch command recently learned to extend the --jobs=<n> option to
> cover the --multiple mode: it will run multiple fetches in parallel.
> 
> Together with the recent support to write commit-graphs automatically after
> each fetch by setting fetch.writeCommitGraph, this led to frequent issues
> where the commit-graph-chain.lock file could not be created because a
> parallel job had already created it.
> 
> This pair of patches first introduces the command-line option 
> --write-commit-graph (together with the --no-* variant) and then uses it to
> avoid writing the commit-graph until all fetch jobs are complete.

Thanks, the whole thing looks clearly explained and the patches themselves look good. And having "--[no-]write-commit-graph" is a good thing even independent of the problem you're fixing.

I wondered if it was worth having a test in the second patch, but I think it would be inherently racy. So it's probably not worth the trouble.

-Peff