[OSM-dev] Mapnik's speed rendering slow ?

[Jon Burgess]

2008/11/8 sylvain letuffe <liste at letuffe.org>:
> Hi there,
>
> I'have set up a tiles server based on mapnik that I plan to use (for now) for
> France only.
> ( Very good wiki page explaining that)
> My setup is : debian etch 64/mapnik 0.5.1/postGIS/generate_tiles.py
> with a quite common machine : dual core 2.5GHZ / 2Go RAM
>
> After much fighting I finaly made it work, and I am happy on all aspects, but
> speed.
>
> While the Mapnik at openstreetmap.org does the rendering (until level 18 if I
> see it well) in something like around ~24 hours, I am currently doing it for
> france (600Mo of osm data) until level 14 at a poor ~15 hours time
>
> Unless the server over there is a martian one clocked at 10^16 Hz, I think I'm
> doing something wrong, but what ?
>
> I was searching on the wiki/doc at mapnik but didn't find tips for that
>
> The only thing I changed in generate_tiles.py is :
> minZoom = 5
> maxZoom = 16
> bbox = (-4, 42.0,8,50.0)
> render_tiles(bbox, mapfile, tile_dir, minZoom, maxZoom)
>
> Symptoms to help :
> - The CPU is fed up at 100% ( load 1.00)
> - The memory is almost unused (5Mo for postgres !! 60Mo for generate_tiles.py)
> - The disk is unused
> - A tile takes ~0.5s to be generated
> - Severall thousand of "Empty Tile" messages appears during the process, while
> still taking ~0.5s
> Does this benchmark looks okay ?

0.5s per tile looks about right. The main tile server does not manage
to render all z18 tiles in 24 hours.

* It only renders the tiles that are looked at. This is less than 1%
of all the possible tiles.
* It will attempt to render new tiles on the fly if they don't yet exist.
* A background process re-renders all the previous tiles. This takes
about 7 days to run.

This is handled by a special Apache module called mod_tile.

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

This is only useful if you have the appropriate access on the server
to setup and install this module. If you just have a plain file
serving web host then you may need to stick with static pre-rendered
tiles.

-- 
    Jon