vc-git-state very slow, waiting for `git diff-index`, in large repositories

vc-git-state very slow, waiting for `git diff-index`, in large repositories

[Matt McClure]

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Emacs opens files from one of my largest Git repositories very slowly. It
looks like it spends most of that time waiting for `git diff-index -z HEAD
-- <file>`.

I upgraded this morning to
http://emacsformacosx.com/emacs-builds/Emacs-2012-07-28-109240-universal-10.6.8.dmghoping
that it would include the fix for
http://debbugs.gnu.org/cgi/bugreport.cgi?bug=11757 and that that would make
Emacs fast enough. But it was still very slow.

I see there's another open ticket citing the call to `git diff-index` from
`vc-git-state`: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8288

Applying the workaround from comment 14 in that ticket works for me, but it
seems like it would be better to address the problem closer to the root in
the Emacs source and/or in Git.

What would you recommend?

-- 
Matt McClure
http://www.matthewlmcclure.com
http://www.mapmyfitness.com/profile/matthewlmcclure

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Re: vc-git-state very slow, waiting for `git diff-index`, in large repositories

[Dmitry Gutov]

Hi Matt,

Matt McClure <matthewlmcclure@gmail.com> writes:
 > Emacs opens files from one of my largest Git repositories very 
slowly. It looks
 > like it spends most of that time waiting for `git diff-index -z HEAD 
-- <file>`.
 >
 > I upgraded this morning to
 > 
http://emacsformacosx.com/emacs-builds/Emacs-2012-07-28-109240-universal-10.6.8.dmg
 > hoping that it would include the fix for
 > http://debbugs.gnu.org/cgi/bugreport.cgi?bug=11757 and that that 
would make
 > Emacs fast enough. But it was still very slow.

11757 was totally unrelated.

 > I see there's another open ticket citing the call to `git diff-index` 
from
 > `vc-git-state`: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8288
 >
 > Applying the workaround from comment 14 in that ticket works for me, 
but it
 > seems like it would be better to address the problem closer to the 
root in the
 > Emacs source and/or in Git.
 >
 > What would you recommend?

I'd recommend timing 'git diff-index -z HEAD -- <file>' vs 'git status
--short <file>' vs 'git status -z --porcelain <file>' in the console on
your real repository and posting the numbers to the bug 8288.
And maybe contributing an example patch that works for you. The function
responsible for this is `vc-git-state'.

--Dmitry

Re: vc-git-state very slow, waiting for `git diff-index`, in large repositories

[Matt McClure]

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Hi Dmitry,

On Wed, Aug 1, 2012 at 12:19 PM, Dmitry Gutov <dgutov@yandex.ru> wrote:

> I'd recommend timing 'git diff-index -z HEAD -- <file>' vs 'git status
> --short <file>' vs 'git status -z --porcelain <file>' in the console on
> your real repository and posting the numbers to the bug 8288.
> And maybe contributing an example patch that works for you. The function
> responsible for this is `vc-git-state'.


Both `git diff-index` and `git status` were comparably slow at least to my
subjective perception. After archiving old branches and a garbage clean --
`git tag`, `git branch -d`, `git gc` -- both perform fast enough again. For
the time being, I think I retract my earlier belief that I was seeing the
same thing as described in bug 8288.

Thanks for your help.

Matt

-- 
Matt McClure
http://www.matthewlmcclure.com
http://www.mapmyfitness.com/profile/matthewlmcclure

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