Re: git clean performance issues

From: Jeff King <peff@peff.net>
Date: Apr 4, 2015, 19:55 UTC
Message-ID: <20150404195507.GA31763@peff.net>
In-Reply-To: <CAMpP7NY++BwV+UygRj1C6Zsf=jE-z1AQuN3On0HeEqQpKGQtqw@mail.gmail.com>

On Sat, Apr 04, 2015 at 08:32:45PM +0200, erik elfström wrote:

Show 10 quoted lines

> In my scenario get_ref_cache will be called 10000+ times, each time
> with a new path. The final few calls will need to search through and
> compare 10000+ entries before realizing that there is no existing
> entry. This quickly ads up to 100 million+ calls to strcmp().
> 
> From what I can understand, the calls to get_ref_cache in this
> scenario will never do any useful work. Is this correct? If so, would
> it be possible to bypass it, maybe by calling
> resolve_gitlink_ref_recursive directly or by using some other way of
> checking for the presence of a git repo in clean.c:remove_dirs?

I think this is the same issue that was discussed here:

  http://thread.gmane.org/gmane.comp.version-control.git/265560/focus=265585

There is some discussion of a possible fix in that thread. I was hoping that Andreas was going to look further and produce a patch, but I imagine he got busy with other things. Do you want to try picking it up?

-Peff