On Fri, Jul 2, 2021 at 3:39 PM Ævar Arnfjörð Bjarmason [off-list ref] wrote:

On Thu, Jul 01 2021, ZheNing Hu via GitGitGadget wrote:

quoted

The performance for `git cat-file --batch-all-objects
--batch-check` on the Git repository itself with performance
testing tool `hyperfine` changes from 669.4 ms ±  31.1 ms to
1.134 s ±  0.063 s.

The performance for `git cat-file --batch-all-objects --batch

quoted

/dev/null` on the Git repository itself with performance testing

tool `time` change from "27.37s user 0.29s system 98% cpu 28.089
total" to "33.69s user 1.54s system 87% cpu 40.258 total".

This new feature is really nice, but that's a really bad performance
regression. A lot of software in the wild relies on "cat-file --batch"
to be *the* performant interface to git for mass-extrction of object
data.

That's in increase of ~70% and ~20%, respectively. Have you dug into
(e.g. with a profiler) where we're now spending all this time?

Yeah, I think it's better to discuss this performance issue as part of
the discussion of this series, instead of as part of the discussion of
the blog posts.