Re: [BUG] "git describe --match" performance

From: Kristoffer Haugsbakk <kristofferhaugsbakk@fastmail.com>
Date: Oct 31, 2024, 16:14 UTC
Message-ID: <469d82f8-4883-4c87-b681-288a0520e745@app.fastmail.com>
In-Reply-To: <20241031114731.GA608553@coredump.intra.peff.net>

On Thu, Oct 31, 2024, at 12:47, Jeff King wrote:

Show 10 quoted lines

>   git commit-graph write --reachable
>
> That reduces the slow case for me by a factor of 10. And likewise other
> traversal operations should get faster.
>
> I think we'll build the commit graph file by default these days when you
> run "git gc". But we don't build it immediately after cloning. Perhaps
> we should change that.
>
> -Peff

There was this thread from last year where Rohit cloned Linux and the command took more than twelve seconds. Then git-commit-graph(1) fixed it.

https://lore.kernel.org/git/CAKazavxTXwcZFtL2XyU3MpaUR=snWY8w8Lwpco+mkbqm2nWE=w@mail.gmail.com/

It would be nice if the graph was written on clone. With the status quo you might think that there is performance bug (if that’s the term) somewhere. Then you make a reproduction script using git-clone(1) in order to have a blank slate. Of course it reproduces every time. But the slow git-log(1) doesn’t happen for people who have had the repo long enough for a GC to hit.