Re: Significant performance waste in git-svn and friends

From: Mike Hommey <mh@glandium.org>
Date: Sep 6, 2007, 05:52 UTC
Message-ID: <20070906055211.GC5741@glandium.org>
In-Reply-To: <7vd4wwj16d.fsf@gitster.siamese.dyndns.org>

On Wed, Sep 05, 2007 at 01:40:42PM -0700, Junio C Hamano <gitster@pobox.com> wrote:

Show 7 quoted lines

> Mike Hommey <mh@glandium.org> writes:
> 
> > The same things obviously apply to git-cvsimport and other scripts
> > calling git-hash-object a lot.
> 
> I *obviously* hate this patch, as it makes this Porcelain
> command to be aware of the internal representation too much.

The patch was not supposed to be applied. I said it was lame ;) It was more of a proof of concept.

Anyways, thinking a bit more about it, I was wondering if it wouldn't be a good idea to have Git.pm have a "native" implementation (by native I mean a .so module) for low-level plumbing tools such as hash-object, cat-file and such.

Obviously, reinventing the wheel is not good, so this native implementation would be using a "git library" API, such as what has been done under SoC (though I don't know if this API exposes low-level plumbing functions)

> I wonder if letting fast-import handle the object creation is an
> option, though.

It could, probably. The reason I didn't use it is that it was way quicker to hack a 10 lines patch to create the blobs by hand than it would have been to fork a fast-import object at the correct place during git-svn initialization and piping to it at the appropriate times.

My goal was only to check how faster this would make it not to fork a git-hash-object per blob.

Mike