git@vger.kernel.org mailing list mirror (one of many)
 help / color / mirror / code / Atom feed
From: Jeff King <peff@peff.net>
To: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Cc: "Martin Fick" <mfick@codeaurora.org>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Derrick Stolee" <stolee@gmail.com>,
	"Lars Schneider" <larsxschneider@gmail.com>,
	git <git@vger.kernel.org>, "Duy Nguyen" <pclouds@gmail.com>
Subject: Re: worktrees vs. alternates
Date: Wed, 16 May 2018 12:23:43 -0700	[thread overview]
Message-ID: <20180516192343.GB3417@sigill.intra.peff.net> (raw)
In-Reply-To: <e8776c83-ea57-456d-5bc8-ca2fc990bed0@linuxfoundation.org>

On Wed, May 16, 2018 at 03:01:13PM -0400, Konstantin Ryabitsev wrote:

> On 05/16/18 14:26, Martin Fick wrote:
> > If you are going to keep the unreferenced objects around 
> > forever, it might be better to keep them around in packed 
> > form?
> 
> I'm undecided about that. On the one hand this does create lots of small
> files and inevitably causes (some) performance degradation. On the other
> hand, I don't want to keep useless objects in the pack, because that
> would also cause performance degradation for people cloning the "mother
> repo." If my assumptions on any of that are incorrect, I'm happy to
> learn more.

I implemented "repack -k", which keeps all objects and just rolls them
into the new pack (along with any currently-loose unreachable objects).
Aside from corner cases (e.g., where somebody accidentally added a 20GB
file to an otherwise 100MB-repo and then rolled it back), it usually
doesn't significantly affect the repository size.

And it generally should not cause performance problems for people
cloning, since Git will create a custom pack for each client with only
the reachable objects.

There _is_ an interesting corner case where a reachable object might be
a delta against an unreachable one, which can cause a clone to have to
break that relationship and find a new delta. At GitHub we have some
custom code that tries to avoid these kind of delta dependencies (not
just to unreachable objects, but to other forks that share object
storage). You can see the patch at:

  https://github.com/peff/git jk/delta-islands

-Peff

  parent reply	other threads:[~2018-05-16 19:23 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-16  8:13 worktrees vs. alternates Lars Schneider
2018-05-16  9:29 ` Ævar Arnfjörð Bjarmason
2018-05-16  9:42   ` Robert P. J. Day
2018-05-16 11:07     ` Ævar Arnfjörð Bjarmason
2018-05-16  9:51   ` Lars Schneider
2018-05-16 10:33     ` Ævar Arnfjörð Bjarmason
2018-05-16 13:02       ` Derrick Stolee
2018-05-16 14:58         ` Konstantin Ryabitsev
2018-05-16 15:34           ` Ævar Arnfjörð Bjarmason
2018-05-16 15:49             ` Konstantin Ryabitsev
2018-05-16 17:54               ` Ævar Arnfjörð Bjarmason
2018-05-16 17:14           ` Martin Fick
2018-05-16 17:41             ` Konstantin Ryabitsev
2018-05-16 18:02               ` Ævar Arnfjörð Bjarmason
2018-05-16 18:12                 ` Konstantin Ryabitsev
2018-05-16 18:26                   ` Martin Fick
2018-05-16 19:01                     ` Konstantin Ryabitsev
2018-05-16 19:03                       ` Martin Fick
2018-05-16 19:11                         ` Konstantin Ryabitsev
2018-05-16 19:18                           ` Martin Fick
2018-05-16 19:23                       ` Jeff King [this message]
2018-05-16 19:29                         ` Konstantin Ryabitsev
2018-05-16 19:37                           ` Jeff King
2018-05-16 19:40                             ` Martin Fick
2018-05-16 20:06                               ` Jeff King
2018-05-16 20:43                                 ` Martin Fick
2018-05-16 20:02                             ` Konstantin Ryabitsev
2018-05-16 20:17                               ` Jeff King
2018-05-17  0:43                               ` Sitaram Chamarty
2018-05-17  3:31                                 ` Jeff King
2018-05-19  5:45                                   ` Duy Nguyen
2018-05-16 19:14           ` Jeff King
2018-05-16 21:18             ` Stefan Beller
2018-05-16 23:45               ` Jeff King

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=20180516192343.GB3417@sigill.intra.peff.net \
    --to=peff@peff.net \
    --cc=avarab@gmail.com \
    --cc=git@vger.kernel.org \
    --cc=konstantin@linuxfoundation.org \
    --cc=larsxschneider@gmail.com \
    --cc=mfick@codeaurora.org \
    --cc=pclouds@gmail.com \
    --cc=stolee@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).