Re: Git blame performance on files with a lot of history

From: Bryan Turner <bturner@atlassian.com>
Date: Dec 14, 2018, 19:10 UTC
Message-ID: <CAGyf7-EZaiVBnoBfRJXAK7KdaXzPaDFVocUrB8LQNU_Hi16u7g@mail.gmail.com>
In-Reply-To: <CABXAcUzoNJ6s3=2xZfWYQUZ_AUefwP=5UVUgMnafKHHtufzbSA@mail.gmail.com>

On Fri, Dec 14, 2018 at 10:29 AM Clement Moyroud <clement.moyroud@gmail.com> wrote:

Show 8 quoted lines

>
> Hello,
>
> My group at work is migrating a CVS repo to Git. The biggest issue we
> face so far is the performance of git blame, especially compared to
> CVS on the same file. One file especially causes us trouble: it's a
> 30k lines file with 25 years of history in 3k+ commits. The complete
> repo has 200k+ commits over that same period of time.

After you converted the repository from CVS to Git, did you run a manual repack?

The process of converting a repository from another SCM often results in poor delta chain selections which result in a repository that's unnecessarily large on disk, and/or performs quite slowly.

Something like `git repack -Adf --depth=50 --window=200` discards the existing delta chains and chooses new ones, and may result in significantly improved performance. A smaller depth, like --depth=20, might result in even more performance improvement, but may also make the repository larger on disk; you'll need to find the balance that works for you.

Might be something worth testing, if you haven't?

Bryan