[PATCH] git: improve changelog and summary performance for large repos

[Tomáš Musil]

Hello,

we have recently converted a large repo (22k revisions, 4k tags) from 
Mercurial to Git and noticed a major slowdown when loading summary (8 
seconds) and changelog (24 seconds) pages, when for Mercurial repo the 
pages show basically instantly.

I have tracked down the issues to:

1. _empty() loads all revisions but just checking if repo has "head" 
seems to do the trick
2. _heads() loads and iterates over all refs (including tags) but later 
only checks /refs/heads and /refs/remotes/origin
3. SubprocessIOChunker's default buffer_size and chunk_size seem to be 
pretty low in _run_git_command when running "git log" to get all revisions

I attempted to address the first two points in the attached patch, in 
the third point I just mutiplied the defaults by 100 which seems to be 
enough for our repo but definitely is not a properly calculated solution.

Overall these changes dropped summary loading time to <2sec and 
changelog to <3sec for our large repo.

Thank you for keeping the Kallithea project alive.

Best regards,

Tomas
-------------- next part --------------
A non-text attachment was scrubbed...
Name: git_heads.patch
Type: text/x-patch
Size: 1555 bytes
Desc: not available
URL: <http://lists.sfconservancy.org/pipermail/kallithea-general/attachments/20260424/28296c06/attachment.bin>