Re: git fetch slow as molasses due to tag downloading

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Dec 14, 2006, 16:05 UTC
Message-ID: <Pine.LNX.4.63.0612141701440.3635@wbgn013.biozentrum.uni-wuerzburg.de>
In-Reply-To: <elrr8j$a02$1@sea.gmane.org>

Hi,

On Thu, 14 Dec 2006, Han-Wen Nienhuys wrote:

Show 11 quoted lines

> just upgraded our autobuilder from 1.4.3 to 1.4.4.2.
> 
> Now, our standard download command comes to a complete halt.  Judging
> >from the "ps -ef" apparently, it does 
> 
>    git-show-ref --verify --quiet -- [TAG]
> 
> This is done for every one of the 1500 tags that are in my repository. 
> At approx 20 tags per second this takes an awful lot of time. 
> 
> 1. Is this necessary?

Yes. The purpose is to check which tags have not yet been fetched.

> 2. Is this efficient?  Wouldn't doing all tags in a single git-show-ref 
> invocation be potentially quicker?

It is not efficient. But it cannot be solved like you propose, since it is inside a loop, and a "continue" is executed when the tag exists already.

IMHO this should be solved as a filter: "git-show-ref --stdin --show-invalid". Thus, git does not have to traverse _every_ ref for _every_ incoming tag.

Ciao, Dscho