Re: upload-pack is slow with lots of refs

> On Wed, Oct 3, 2012 at 8:03 PM, Jeff King <peff@peff.net> wrote:
> > What version of git are you using?  In the past year or so, I've made
> > several tweaks to speed up large numbers of refs, including:
> >
> >   - cff38a5 (receive-pack: eliminate duplicate .have refs, v1.7.6); note
> >     that this only helps if they are being pulled in by an alternates
> >     repo. And even then, it only helps if they are mostly duplicates;
> >     distinct ones are still O(n^2).
> >
> >   - 7db8d53 (fetch-pack: avoid quadratic behavior in remove_duplicates)
> >     a0de288 (fetch-pack: avoid quadratic loop in filter_refs)
> >     Both in v1.7.11. I think there is still a potential quadratic loop
> >     in mark_complete()
> >
> >   - 90108a2 (upload-pack: avoid parsing tag destinations)
> >     926f1dd (upload-pack: avoid parsing objects during ref advertisement)
> >     Both in v1.7.10. Note that tag objects are more expensive to
> >     advertise than commits, because we have to load and peel them.
> >
> > Even with those patches, though, I found that it was something like ~2s
> > to advertise 100,000 refs.
> 
> FWIW I bisected between 1.7.9 and 1.7.10 and found that the point at
> which it went from 1.5/s to 2.5/s upload-pack runs on the pathological
> git.git repository was none of those, but:
> 
>     ccdc6037fe - parse_object: try internal cache before reading object db