From: Jeff King <peff@peff.net>
Date: Mon, 28 Jan 2008 05:59:33 GMT
Subject: Re: git-revert is a memory hog
Message-ID: <20080128055933.GA13521@coredump.intra.peff.net>
In-Reply-To: <20080127172748.GD2558@does.not.exist>

On Sun, Jan 27, 2008 at 07:27:48PM +0200, Adrian Bunk wrote:

> <--  snip  -->
> 
> $ git-revert d19fbe8a7
> Auto-merged drivers/input/input.c
> CONFLICT (content): Merge conflict in drivers/input/input.c
> Auto-merged include/linux/input.h
> CONFLICT (content): Merge conflict in include/linux/input.h
> Automatic revert failed.  After resolving the conflicts,
> mark the corrected paths with 'git add <paths>' and commit the result.
> $ 
> 
> <--  snip  -->
> 
> In top you can see that this took > 800 MB of RAM !

I tried to reproduce this, but my peak heap allocation was only around
20MB. Is your repository fully packed? Not packed at all? Can you use
valgrind/massif to figure out where the memory is going?

> I don't know how easy it would be to implement, but shouldn't git-revert 
> be able to be as fast and less memory consuming as
>   git-show d19fbe8a7 | patch -p1 -R

In your case, the patch doesn't apply cleanly, so we end up doing a
3-way merge (in my tests, it is git-merge-recursive which ends up taking
up the memory).

-Peff