[OSM-dev] How is Mapnik Performances ?

[Jon Burgess]

On Mon, 2009-01-05 at 20:46 +0000, Roberto Navoni wrote:
> Hi,
> I have a question for OSM-Developer ;)
> So I'm trying mapnik for render italian OSM planet , but the performance 
> on my sandbox is not so god . I'm using an old one hp laptop that use 
> Ubuntu 8.04 as SO and as hardware use P4 3 Ghz 1 GByte of ram . I see 
> that actualy are rendering only two  tile for second.  I'm usining 
> postgress 8.3 as db. Are there some optimization for speed up the render 
> time.
> How many mapnik i can start on a single cpu ? The performance is better ?

Are you using generate_tiles.py for rendering your tiles?
Is the web server under your control or are you serving static files via
a 3rd party web host?

The main tile.openstreetmap.org server uses mod_tile[1] which uses
several optimisation tricks to improve the performance but you can only
get the full benefit of this if you can install a custom Apache module.

- multithreaded rendering (should exploit improve efficiency if you have
hyperthreading in your CPU).
- rendering and storing tiles in "meta-tiles" (8x8 at once).
- rendering on-demand, avoiding the need to pre-render lots of tiles

If you can't install the Apache module then the mod_tile render daemon
can be used standalone with the speedtest & convert_meta tools to
generate a tree containing plain PNG files for uploading to a 3rd party
web host. I can provide more details if you are interested in this.

Last time I benchmarked the tile.openstreetmap.org server it was
rendering approximately 600 tiles/s using 2 x dual core Opteron CPUs.
The osm.xml file has got significantly more complex since I did those
tests so the numbers are probably a bit slower now. Even so, your P4
should manage more than 10 times your current performance.

	Jon

1: http://wiki.openstreetmap.org/index.php/Mod_tile