From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 24 Aug 2020 21:19:35 GMT
Subject: Re: [PATCH 7/7] index-pack: make quantum of work smaller
Message-ID: <xmqqk0xn3fo8.fsf@gitster.c.googlers.com>
In-Reply-To: <3e69f41f19535fa2c04fae6adc78bcc4f052d523.1598296530.git.jonathantanmy@google.com>

Jonathan Tan <jonathantanmy@google.com> writes:

> Currently, when index-pack resolves deltas, it does not split up delta
> trees into threads: each delta base root (an object that is not a
> REF_DELTA or OFS_DELTA) can go into its own thread, but all deltas on
> that root (direct or indirect) are processed in the same thread.
>
> This is a problem when a repository contains a large text file (thus,
> delta-able) that is modified many times - delta resolution time during
> fetching is dominated by processing the deltas corresponding to that
> text file.

We favor wide and shallow delta trees for both reduced storage
footprint and lower runtime overhead, so optimizing the index-pack
for that use case makes a lot of sense.