Re: name-rev --stdin is slow

From: Daniel Barkalow <barkalow@iabervon.org>
Date: Jun 19, 2008, 23:00 UTC
Message-ID: <alpine.LNX.1.00.0806191849540.19665@iabervon.org>
In-Reply-To: <485AD90E.6000309@gmail.com>

On Fri, 20 Jun 2008, Lea Wiemann wrote:

Show 8 quoted lines

> Daniel Barkalow wrote:
> > Actually, I think it's the reverse: without --stdin, name-rev can do a first
> > pass that lets it eliminate a lot of data from consideration; with --stdin,
> > it doesn't know if an item it hasn't seen is going to need some data, and so
> > it's conservative and doesn't eliminate anything,
> 
> Are you sure that's the case?  time git-name-rev --stdin < /dev/null gives the
> same high startup time without looking up anything.

Ah, okay. There's a startup pass that goes through all of the refs (tags in particular), and does stuff with them, but only if they aren't filtered out.

> Anyways, it would be great if someone could try to fix that, since a 6-second
> startup time on a repository like linux-2.6 makes the --stdin option unusable
> for applications like gitweb (for which it would actually be quite useful to
> reduce the number of forks).

It might be possible to collect all of the input, set up the filter, and do the (now cheaper) initial pass, but I don't think that would offer any real advantage over just collecting them in the caller and calling name-rev with a long command line.

	-Daniel
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