Re: Bug in 2.26: git-fetch fetching too many objects?

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Apr 21, 2020, 19:36 UTC
Message-ID: <20200421193611.GA103469@google.com>
In-Reply-To: <xmqqblnkodi4.fsf@gitster.c.googlers.com>

Hi,

Junio C Hamano wrote:

> Jonathan Nieder <jrnieder@gmail.com> writes:
>> Dixit, Ashutosh wrote:

Show 9 quoted lines

>>> I am seeing a strange behavior in git-fetch in 2.26. I frequently fetch
>>> from a couple of linux kernel remotes (so you will have an idea how big the
>>> repo is). I have a different system with 2.20 on which I never see a
>>> problem.
>> ...
>> I suspect this is related to the change that protocol v2 does to use
>> stateless-rpc even in stateful protocols.  If my suspicion is correct,
>> then the same behavior would show up with protocol v0 over http and
>> https as well.

[...]

> This is at least the fourth time we hear that v2 may not be ready
> for the real-world use.  Perhaps we should revert the default flip
> on the maintenance track while we hunt for bugs and improve the
> protocol support?

That feels to me like an overreaction, since these are all reports of the same issue that we have a fix to. Shouldn't we just flip the default for fetch.negotiationAlgorithm to skipping? If we revert to buy time, what would we do with that time?

In other words, if I understand correctly, it's describing an issue that also exists in protocol v0 for https. I would be *very* interested in any evidence one way or another about whether I am understanding correctly. If we flip the default, I don't see how we'll get that evidence, since we've been using protocol v2 as the default at $DAYJOB for quite a long time now.

Thanks, Jonathan