Re: Dump http servers still slow?

From: Junio C Hamano <junkio@cox.net>
Date: Jul 30, 2005, 02:11 UTC
Message-ID: <7vmzo56o0u.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <1122645821.4263.6.camel@localhost.localdomain>

Darrin Thompson <darrint@progeny.com> writes:

Show 10 quoted lines

> Ok... so lets check my assumptions:
>
> 1. Pack files should reduce the number of http round trips.
> 2. What I'm seeing when I check out mainline git is the acquisition of a
> single large pack, then 600+ more recent objects. Better than before,
> but still hundreds of round trips.
> 3. If I wanted to further speed up the initial checkout on my own
> repositories I could frequently repack my most recent few hundred
> objects.
> 4. If curl had pipelining then less pack management would be needed.

All true. Another possibility is to make multiple requests in parallel; if curl does not do pipelining, either switch to something that does, or have more then one process using curl.

The dumb server preparation creates three files, two of which is currently used by clone (one is list of packs, the other is list of branches and tags). The third one is commit ancestry information. The commit walker could be taught to read it to figure out what commits it still needs to fetch without waiting for the commit being retrieved to be parsed.

Sorry, I am not planning to write that part myself.

One potential low hanging fruit is that even for cloning via git:// URL we _might_ be better off starting with the dumb server protocol; get the list of statically prepared packs and obtain them upfront before starting the clone-pack/upload-pack protocol pair.