From: Jonathan Nieder <jrnieder@gmail.com>
To: Jeff King <peff@peff.net>
Cc: Jonathan Tan <jonathantanmy@google.com>, git@vger.kernel.org
Subject: Re: [PATCH] gc: do not warn about too many loose objects
Date: Mon, 16 Jul 2018 13:37:53 -0700 [thread overview]
Message-ID: <20180716203753.GE11513@aiede.svl.corp.google.com> (raw)
In-Reply-To: <20180716202915.GC25189@sigill.intra.peff.net>
Jeff King wrote:
> On Mon, Jul 16, 2018 at 12:54:31PM -0700, Jonathan Nieder wrote:
>> Even restricting attention to the warning, not the exit code, I think
>> you are saying the current behavior is acceptable. I do not believe
>> it is.
>
> I didn't say that at all. The current situation sucks,
Thanks for clarifying. That helps.
> and I think the
> right solution is to pack the unreachable objects instead of exploding
> them.
That seems like a huge widening in scope relative to what this
original patch tackled. I'm not aware of a way to do this without
breaking compatibility with the current (broken) race prevention. If
you're saying that breaking compatibility in that way is okay with
you, then great!
[...]
>> I think you are saying Jonathan's patch makes the behavior
>> worse, and I'm not seeing it. Can you describe an example user
>> interaction where the current behavior would be better than the
>> behavior after Jonathan's patch? That might help make this discussion
>> more concrete.
>
> It makes it worse because there is nothing to throttle a "gc --auto"
> that is making no progress.
[...]
> With the current code, that produces a bunch of annoying warnings for
> every commit ("I couldn't gc because the last gc reported a warning").
> But after Jonathan's patch, every single commit will do a full gc of the
> repository. In this tiny repository that's relatively quick, but in a
> real repo it's a ton of CPU and I/O, all for nothing.
I see. Do I understand correctly that if we find a way to print the
warning but not error out, that would be good enough for you?
[...]
>> Have you looked over the discussion in "Loose objects and unreachable
>> objects" in Documentation/technical/hash-function-transition.txt? Do
>> you have thoughts on it (preferrably in a separate thread)?
>
> It seems to propose putting the unreachable objects into a pack. Which
> yes, I absolutely agree with (as I thought I'd been saying in every
> single email in this thread).
I figured you were proposing something like
https://public-inbox.org/git/20180113100734.GA30698@sigill.intra.peff.net/,
which is still racy (because it does not handle the freshening in a safe
way).
[...]
> Even if we were going to remove this message to help the
> daemonized case, I think we'd want to retain it for the non-daemon case.
Interesting. That should be doable, e.g. following the approach
described below.
[...]
>> A simple way to do that without changing formats is to truncate the
>> file when exiting with status 0.
>
> That's a different behavior than what we do now (and what was suggested
> earlier), in that it assumes that anything written to stderr is OK for
> gc to hide from the user if the process exits with code zero.
>
> That's probably OK in most cases, though I wonder if there are corner
> cases. For example, if you have a corrupt ref, we used to say "error:
> refs/heads/foo does not point to a valid object!" but otherwise ignore
> it. These days git-gc sets REF_PARANOIA=1, so we'll actually barf on a
> corrupt ref. But I wonder if there are other cases lurking.
What decides it for me is that the user did not invoke "git gc --auto"
explicitly, so anything "git gc --auto" prints is tangential to what
the user was trying to do. If the gc failed, that is worth telling
them, but if e.g. it encountered a disk I/O error reading and
succeeded on retry (to make up a fake example), then that's likely
worth logging to syslog but it's not something the user asked to be
directly informed about.
Thanks,
Jonathan
next prev parent reply other threads:[~2018-07-16 20:37 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-16 17:27 [PATCH] gc: do not warn about too many loose objects Jonathan Tan
2018-07-16 17:51 ` Jeff King
2018-07-16 18:22 ` Jonathan Nieder
2018-07-16 18:52 ` Jeff King
2018-07-16 19:09 ` Jonathan Nieder
2018-07-16 19:41 ` Jeff King
2018-07-16 19:54 ` Jonathan Nieder
2018-07-16 20:29 ` Jeff King
2018-07-16 20:37 ` Jonathan Nieder [this message]
2018-07-16 21:09 ` Jeff King
2018-07-16 21:40 ` Jonathan Nieder
2018-07-16 21:45 ` Jeff King
2018-07-16 22:03 ` Jonathan Nieder
2018-07-16 22:43 ` Jeff King
2018-07-16 22:56 ` Jonathan Nieder
2018-07-16 23:26 ` Jeff King
2018-07-17 1:53 ` Jonathan Nieder
2018-07-17 8:59 ` Ævar Arnfjörð Bjarmason
2018-07-17 14:03 ` Jonathan Nieder
2018-07-17 15:24 ` Ævar Arnfjörð Bjarmason
2018-07-17 20:27 ` Jeff King
2018-07-18 13:11 ` Ævar Arnfjörð Bjarmason
2018-07-18 17:29 ` Jeff King
2018-07-17 15:59 ` Duy Nguyen
2018-07-17 18:09 ` Junio C Hamano
2018-07-16 19:15 ` Elijah Newren
2018-07-16 19:19 ` Jonathan Nieder
2018-07-16 20:21 ` Elijah Newren
2018-07-16 20:35 ` Jeff King
2018-07-16 20:56 ` Jonathan Nieder
2018-07-16 21:12 ` Jeff King
2018-07-16 19:52 ` Jeff King
2018-07-16 20:16 ` Elijah Newren
2018-07-16 20:38 ` Jeff King
2018-07-16 21:09 ` Elijah Newren
2018-07-16 21:21 ` Jeff King
2018-07-16 22:07 ` Elijah Newren
2018-07-16 22:55 ` Jeff King
2018-07-16 23:06 ` Elijah Newren
2018-07-16 21:31 ` Jonathan Nieder
2018-07-17 6:51 ` [PATCH v2 0/3] gc --auto: do not return error for prior errors in daemonized mode Jonathan Nieder
2018-07-17 6:53 ` [PATCH 1/3] gc: improve handling of errors reading gc.log Jonathan Nieder
2018-07-17 18:19 ` Junio C Hamano
2018-07-17 19:58 ` Jeff King
2018-07-17 6:54 ` [PATCH 2/3] gc: exit with status 128 on failure Jonathan Nieder
2018-07-17 18:22 ` Junio C Hamano
2018-07-17 19:59 ` Jeff King
2018-09-17 18:33 ` Jeff King
2018-09-17 18:40 ` Jonathan Nieder
2018-09-18 17:30 ` Jeff King
2018-07-17 6:57 ` [PATCH 3/3] gc: do not return error for prior errors in daemonized mode Jonathan Nieder
2018-07-17 20:13 ` Jeff King
2018-07-18 16:21 ` Junio C Hamano
2018-07-18 17:22 ` Jeff King
2018-07-18 18:19 ` Junio C Hamano
2018-07-18 19:06 ` Jeff King
2018-07-18 19:55 ` Junio C Hamano
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