Re: [PATCH] packfile: fix perf regression with many packs

Le 13 août 2026 à 05:04, Johannes Schindelin [off-list ref] a écrit :

Hi Ben,

On Wed, 12 Aug 2026, Ben Knoble wrote:

quoted

quoted

Le 12 août 2026 à 15:15, Johannes Schindelin via GitGitGadget
[off-list ref] a écrit :

[...]
  packfile: fix perf regression with many packs

  This issue was spotted by a Microsoft Git user with the massive
  amount of packfiles typical of an average, long-running monorepo
  checkout.

As a different kind of intermediate solution, would turning on
maintenance for that user’s checkout help? (Not sure that would help CI
clone times unless the server repacks, of course.)

I should have clarified that the issue is a _Scalar_ clone. And
specifically a _Microsoft Git Scalar_ clone.

This matters because, for various reasons that I don't want to elaborate
on because today I'm in need of lifting up my mood, a substantial part of
Microsoft Git failed to get upstreamed to core Git.

One of these is the "shared cache repository", i.e. a bare repository that
is established as an alternate of the actual clone, and into which the
actual scheduled fetches go. For full details, see
https://github.com/microsoft/git/commit/55226d12ed36 (scalar: do
initialize `gvfs.sharedCache`, 2021-05-03).

Now, maintenance _does_ run, usually, on that shared cache repository
(being careful not to inadvertently drop objects merely because they're
unreachable within the shared cache repository). So theoretically, you're
right that maintenance should help this issue.

For reasons (which I don't have the time to find out, but I suspect that
maintenance simply takes too long and does not finish by the time the
machine is shut down for the day), it is still not exactly rare to find
setups with five-digit packfile counts. And since we _can_ handle this
more gracefully, we should ;-)

Ciao,
Johannes

Thanks, very informative!

What I actually meant, sorry if I wasn’t clear, is that maintenance seems likely to help the local (à la PS1) case more than the clone. But maybe it will suffer from the same « takes too long » problem, idk.