Re: What is the status of GSoC 2022 work on making Git use roaring bitmaps?

[Han-Wen Nienhuys <hanwen@google.com>]

On Mon, Jul 31, 2023 at 10:18 PM Taylor Blau <me@ttaylorr.com> wrote:
> I haven't proved conclusively one way or the other where Roaring+Run is
> significantly faster than EWAH or vice-versa. There are some cases where
> the former is a clear winner, and other cases where it's the latter.
>
> In any event, my extremely WIP patches to make this mostly work are
> available here:
>
>   https://github.com/ttaylorr/git/compare/tb/roaring-bitmaps
>

thanks. For anyone reading along, the changes to JGit are here

https://git.eclipse.org/r/c/jgit/jgit/+/203448

I was looking into this because I was hoping that roaring might
decrease peak memory usage.

I don't have firm evidence that it's better or worse, but I did
observe that runtime and memory usage during GC (which is heavy on
bitmap operations due to delta/xor encoding) was unchanged. That makes
me pessimistic that there are significant gains to be had.

> One thing that I was able to do to produce slightly smaller Roaring+Run

Just for my edification: what is "Roaring + Run" ?

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