Re: git svn clone/fetch hits issues with gc --auto

From: Martin Langhoff <martin.langhoff@gmail.com>
To: "Ævar Arnfjörð" <avarab@gmail.com>
Cc: Junio C Hamano <gitster@pobox.com>,
	Jonathan Nieder <jrnieder@gmail.com>,
	e@80x24.org, Git Mailing List <git@vger.kernel.org>
Subject: Re: git svn clone/fetch hits issues with gc --auto
Date: Wed, 10 Oct 2018 07:41:25 -0400	[thread overview]
Message-ID: <CACPiFCKMF2di=waQ5reRtjUFEjuE6DkxxLcN-YnF-SqgE_m=_Q@mail.gmail.com> (raw)
In-Reply-To: <878t36f3ed.fsf@evledraar.gmail.com>

On Wed, Oct 10, 2018 at 7:27 AM Ævar Arnfjörð Bjarmason
<avarab@gmail.com> wrote:
> As Jeff's
> https://public-inbox.org/git/20180716175103.GB18636@sigill.intra.peff.net/
> and my https://public-inbox.org/git/878t69dgvx.fsf@evledraar.gmail.com/
> note it's a bit more complex than that.

Ok, my bad for not reading the whole thread :-) thanks for the kind explanation.

>  - The warning is actionable, you can decide to up your expiration
>    policy.

A newbie-ish user shouldn't need to know git's internal store model
_and the nuances of its special cases_ got get through.

>  - We use this warning as a proxy for "let's not run for a day"

Oh, so _that's_ the trick with creating gc.log? I then understand the
idea of changing to exit 0.

But it's far from clear, and a clear _flag_, and not spitting again
the same warning, or differently-worded warning would be better.

"We won't try running gc, a recent run was deemed pointless until some
time passes. Nothing to worry about."

>  - This conflation of the user-visible warning and the policy is an
>    emergent effect of how the different gc pieces interact, which as I
>    note in the linked thread(s) sucks.

It sure does, and that aspect should be easy to fix...(?)

> So it's creating a lot of garbage during its cloning process that can
> just be immediately thrown away? What is it doing? Using the object
> store as a scratch pad for its own temporary state?

Yeah, thats suspicious and I don't know why. I've worked on other
importers and while those needed 'gc' to generate packs, they didn't
generate garbage objects. After gc, the repo was "clean".

cheers,

m
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