git@vger.kernel.org mailing list mirror (one of many)
 help / color / mirror / code / Atom feed
From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: Jonathan Nieder <jrnieder@gmail.com>,
	Junio C Hamano <gitster@pobox.com>,
	git@vger.kernel.org,
	Ian Jackson <ijackson@chiark.greenend.org.uk>
Subject: Re: [PATCH] rebase: mark the C reimplementation as an experimental opt-in feature (was Re: [ANNOUNCE] Git v2.20.0-rc1)
Date: Wed, 28 Nov 2018 13:21:14 +0100	[thread overview]
Message-ID: <87bm69z939.fsf@evledraar.gmail.com> (raw)
In-Reply-To: <nycvar.QRO.7.76.6.1811281015360.41@tvgsbejvaqbjf.bet>


On Wed, Nov 28 2018, Johannes Schindelin wrote:

> Hi Jonathan,
>
> On Tue, 27 Nov 2018, Jonathan Nieder wrote:
>
>> At https://bugs.debian.org/914695 is a report of a test regression in
>> an outside project that is very likely to have been triggered by the
>> new faster rebase code.
>
> From looking through that log.gz (without having a clue where the test
> code lives, so I cannot say what it is supposed to do, and also: this is
> the first time I hear about dgit...), it would appear that this must be a
> regression in the reflog messages produced by `git rebase`.
>
>> The issue has not been triaged, so I don't know yet whether it's a
>> problem in rebase-in-c or a manifestation of a bug in the test.
>
> It ends thusly:
>
> -- snip --
> [...]
> + git reflog
> + egrep 'debrebase new-upstream.*checkout'
> + test 1 = 0
> + t-report-failure
> + set +x
> TEST FAILED
> -- snap --
>
> Which makes me think that the reflog we produce in *some* code path that
> originally called `git checkout` differs from the scripted rebase's
> generated reflog.
>
>> That said, Google has been running with the new rebase since ~1 month
>> ago when it became the default, with no issues reported by users.  As a
>> result, I am confident that it can cope with what most users of "next"
>> throw at it, which means that if we are to find more issues to polish it
>> better, it will need all the exposure it can get.
>
> Right. And there are a few weeks before the holidays, which should give me
> time to fix whatever bugs are discovered (I only half mind being the only
> one who fixes these bugs).
>
>> In the Google deployment, we will keep using rebase-in-c even if it
>> gets disabled by default, in order to help with that.
>>
>> From the Debian point of view, it's only a matter of time before
>> rebase-in-c becomes the default: even if it's not the default in 2.20,
>> it would presumably be so in 2.21 or 2.22.  That means the community's
>> attention when resolving security and reliability bugs would be on the
>> rebase-in-c implementation.  As a result, the Debian package will most
>> likely enable rebase-in-c by default even if upstream disables it, in
>> order to increase the package's shelf life (i.e. to ease the
>> maintenance burden of supporting whichever version of the package ends
>> up in the next Debian stable).
>>
>> So with either hat on, it doesn't matter whether you apply this patch
>> upstream.
>>
>> Having two pretty different deployments end up with the same
>> conclusion leads me to suspect that it's best for upstream not to
>> apply the revert patch, unless either
>>
>>   (a) we have a concrete regression to address and then try again, or
>>   (b) we have a test or other plan to follow before trying again.
>
> In this instance, I am more a fan of the "let's move fast and break
> things, then move even faster fixing them" approach.
>
> Besides, the bug that Ævar discovered was a bug already in the scripted
> rebase, but hidden by yet another bug (the missing error checking).
>
> I get the pretty firm impression that the common code paths are now pretty
> robust, and only lesser-exercised features may expose a bug (or
> regression, as in the case of the reflogs, where one could argue that the
> exact reflog message is not something we promise not to fiddle with).

Since I raised this 'should we hold off?' I thought I'd chime in and say
that I'm fine with going along with what you suggest and having the
builtin as the default in the final. IOW not merge
jc/postpone-rebase-in-c down.

  reply	other threads:[~2018-11-28 12:21 UTC|newest]

Thread overview: 97+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-13 12:38 [PATCH 0/1] rebase: understand -C again, refactor Johannes Schindelin via GitGitGadget
2018-11-13 12:38 ` [PATCH 1/1] rebase: really just passthru the `git am` options Johannes Schindelin via GitGitGadget
2018-11-13 13:05   ` Junio C Hamano
2018-11-13 15:05   ` Phillip Wood
2018-11-13 19:21     ` Johannes Schindelin
2018-11-13 19:58       ` Phillip Wood
2018-11-13 21:50         ` rebase-in-C stability for 2.20 Ævar Arnfjörð Bjarmason
2018-11-14  0:07           ` Stefan Beller
2018-11-14  9:01             ` [PATCH 0/2] rebase.useBuiltin doc & test mode Ævar Arnfjörð Bjarmason
2018-11-14 14:07               ` Johannes Schindelin
2018-11-14  9:01             ` [PATCH 1/2] rebase doc: document rebase.useBuiltin Ævar Arnfjörð Bjarmason
2018-11-14  9:01             ` [PATCH 2/2] tests: add a special setup where rebase.useBuiltin is off Ævar Arnfjörð Bjarmason
2018-11-14  0:36           ` rebase-in-C stability for 2.20 Elijah Newren
2018-11-14  3:39           ` Junio C Hamano
2018-11-24 20:54           ` [ANNOUNCE] Git v2.20.0-rc1 Ævar Arnfjörð Bjarmason
2018-11-25  1:00             ` Junio C Hamano
2018-11-26  6:10               ` [PATCH] rebase: mark the C reimplementation as an experimental opt-in feature (was Re: [ANNOUNCE] Git v2.20.0-rc1) Junio C Hamano
2018-11-28  4:31                 ` Jonathan Nieder
2018-11-28  9:23                   ` Johannes Schindelin
2018-11-28 12:21                     ` Ævar Arnfjörð Bjarmason [this message]
2018-11-29  4:58                       ` Junio C Hamano
2018-11-29 14:17                     ` Johannes Schindelin
2018-11-29 14:30                       ` Ian Jackson
2018-11-29 15:39                         ` Johannes Schindelin
2018-11-29 15:50                           ` Ian Jackson
2018-11-29 16:14                             ` Johannes Schindelin
2018-11-29 16:26                               ` Ian Jackson
2018-11-26 22:52             ` [ANNOUNCE] Git v2.20.0-rc1 Johannes Schindelin
2018-11-26 23:47               ` Johannes Schindelin
2018-11-28  4:07                 ` Junio C Hamano
2018-11-28  9:30                   ` Johannes Schindelin
2018-11-14 14:22         ` [PATCH 1/1] rebase: really just passthru the `git am` options Johannes Schindelin
2018-11-14  7:29 ` [PATCH 0/1] rebase: understand -C again, refactor Jeff King
2018-11-14 14:28   ` Johannes Schindelin
2018-11-14 16:25 ` [PATCH v2 0/2] " Johannes Schindelin via GitGitGadget
2018-11-14 16:25   ` [PATCH v2 1/2] rebase: really just passthru the `git am` options Johannes Schindelin via GitGitGadget
2018-11-14 16:25   ` [PATCH v2 2/2] rebase: validate -C<n> and --whitespace=<mode> parameters early Johannes Schindelin via GitGitGadget
2018-11-14 16:37     ` Phillip Wood
2018-11-14 21:24       ` Johannes Schindelin
2018-11-19 12:38     ` Ævar Arnfjörð Bjarmason
2018-11-19 21:37       ` Git Test Coverage Report (v2.20.0-rc0) Ævar Arnfjörð Bjarmason
2018-11-20 10:58       ` [PATCH v2 2/2] rebase: validate -C<n> and --whitespace=<mode> parameters early Johannes Schindelin
2018-11-20 11:42         ` [PATCH] rebase: mark a test as failing with rebase.useBuiltin=false Ævar Arnfjörð Bjarmason
2018-11-20 19:55           ` Johannes Schindelin
  -- strict thread matches above, loose matches on Subject: below --
2018-11-19  2:54 Git Test Coverage Report (v2.20.0-rc0) Derrick Stolee
2018-11-19 15:40 ` Derrick Stolee
2018-11-19 16:21   ` Jeff King
2018-11-19 18:44     ` Jeff King
2018-11-19 19:00   ` Ben Peart
2018-11-19 21:06     ` Derrick Stolee
2018-11-20 11:34   ` Jeff King
2018-11-20 12:17     ` Derrick Stolee
2018-11-20 12:40       ` Jeff King
2018-11-19 18:33 ` Ævar Arnfjörð Bjarmason
2018-11-19 18:51   ` [PATCH] tests: add a special setup where rebase.useBuiltin is off (Re: Git Test Coverage Report (v2.20.0-rc0)) Jonathan Nieder
2018-11-19 21:03     ` Ævar Arnfjörð Bjarmason
2018-11-19 19:10   ` Git Test Coverage Report (v2.20.0-rc0) Derrick Stolee
2018-11-19 19:39     ` Ævar Arnfjörð Bjarmason
2018-11-19 19:44       ` Derrick Stolee
2018-11-19 21:31   ` Derrick Stolee
2018-11-20 20:43     ` Johannes Schindelin
2018-11-21 15:20 [ANNOUNCE] Git v2.20.0-rc1 Junio C Hamano
2018-11-22 15:58 ` Ævar Arnfjörð Bjarmason
2018-11-22 19:27   ` Eric Sunshine
2018-11-22 21:12     ` [PATCH 0/2] format-patch: pre-2.20 range-diff regression fix Ævar Arnfjörð Bjarmason
2018-11-22 21:12     ` [PATCH 1/2] format-patch: add a more exhaustive --range-diff test Ævar Arnfjörð Bjarmason
2018-11-24  4:14       ` Junio C Hamano
2018-11-24 11:45         ` Ævar Arnfjörð Bjarmason
2018-11-22 21:12     ` [PATCH 2/2] format-patch: don't include --stat with --range-diff output Ævar Arnfjörð Bjarmason
2018-11-24  2:26       ` Junio C Hamano
2018-11-24  4:17         ` Junio C Hamano
2018-11-28 20:18           ` [PATCH 0/2] format-patch: fix root cause of recent regression Ævar Arnfjörð Bjarmason
2018-11-28 20:18           ` [PATCH 1/2] format-patch: add test for --range-diff diff output Ævar Arnfjörð Bjarmason
2018-11-28 20:18           ` [PATCH 2/2] format-patch: allow for independent diff & range-diff options Ævar Arnfjörð Bjarmason
2018-11-29  2:59             ` Junio C Hamano
2018-11-29 10:07             ` Johannes Schindelin
2018-11-29 10:30               ` Ævar Arnfjörð Bjarmason
2018-11-29 12:12                 ` Johannes Schindelin
2018-11-29 14:35                   ` Ævar Arnfjörð Bjarmason
2018-11-29 15:41                     ` Johannes Schindelin
2018-11-29 16:03                       ` Ævar Arnfjörð Bjarmason
2018-11-29 19:03                         ` Johannes Schindelin
2018-11-30  2:30                         ` Junio C Hamano
2018-11-30  4:27                           ` [PATCH] format-patch: do not let its diff-options affect --range-diff (was Re: [PATCH 2/2] format-patch: allow for independent diff & range-diff options) Junio C Hamano
2018-11-30  8:57                             ` Junio C Hamano
2018-11-30  9:24                               ` Ævar Arnfjörð Bjarmason
2018-11-30 12:32                               ` Johannes Schindelin
2018-11-30  9:31                             ` Eric Sunshine
2018-12-03 13:27                               ` Martin Ågren
2018-12-03 20:07                                 ` [PATCH v2] range-diff: always pass at least minimal diff options Martin Ågren
2018-12-03 21:21                                   ` [PATCH v3] " Eric Sunshine
2018-12-04  1:35                                     ` Junio C Hamano
2018-12-04  5:40                                     ` Martin Ågren
2018-11-30  9:58                         ` [PATCH 2/2] format-patch: allow for independent diff & range-diff options Eric Sunshine
2018-11-26  7:35 ` [ANNOUNCE] Git v2.20.0-rc1 Junio C Hamano
2018-11-26 15:41   ` Elijah Newren
2018-11-27  0:40     ` Junio C Hamano

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87bm69z939.fsf@evledraar.gmail.com \
    --to=avarab@gmail.com \
    --cc=Johannes.Schindelin@gmx.de \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.com \
    --cc=ijackson@chiark.greenend.org.uk \
    --cc=jrnieder@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://80x24.org/mirrors/git.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).