Re: [PATCH v2 1/5] test-list-objects: List a subset of object ids

From: Junio C Hamano <gitster@pobox.com>
Date: Oct 5, 2017, 09:48 UTC
Message-ID: <xmqqvaju6i3p.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20171005084249.sdkimglkxqh2vi4i@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 17 quoted lines

> This is weirdly specific. Can we accomplish the same thing with existing
> tools?
>
> E.g., could:
>
>   git cat-file --batch-all-objects --batch-check='%(objectname)' |
>   shuffle |
>   head -n 100
>
> do the same thing?
>
> I know that "shuffle" isn't available everywhere, but I'd much rather
> see us fill in portability gaps in a general way, rather than
> introducing one-shot C code that needs to be maintained (and you
> wouldn't _think_ that t/helper programs need much maintenance, but try
> perusing "git log t/helper" output; they have to adapt to the same
> tree-wide changes as the rest of the code).

I was thinking about this a bit more, and came to the conclusion that "sort -R" and "shuf" are wrong tools to use. We would want to measure with something close to real world workload. for example, letting

	git rev-list --all --objects

produce the listof objects in traversal order (i.e. this is very similar to the order in which "git log -p" needs to access the objects) and chomping at the number of sample objects you need in your test would give you such a list.