[Tilesathome] Memcached?

Grant Slater openstreetmap at firefishy.com
Thu Jul 17 14:46:30 BST 2008


Ian Dees wrote:
> Spaetz, do you have enough access rights to the tah.osm.org 
> <http://tah.osm.org> server to install memcached? I'm thinking we 
> should cache the tile images just before we send them to the user, and 
> then check the cache when we get a tile request. Even with a 25 or 
> 30MB cache, I imagine we could cache in memory some of the 
> most-visited areas. When a tileset uploads, we could make sure and 
> invalidate the cache enty for it (if it exists).
>
> I could spend some time working on this if you have rights to install 
> memcached and the python bindings.

Serving tiles is unlikely to an expensive process. OS will cache 
filesystem reads regardless.

It would be better to optimise HTTP headers to improve caching (and 
hence offloading the server) and also support Conditional "304 Not 
Modified" HTTP Requests.

See how JonB solved this for the OSM Mapnik layer:
http://trac.openstreetmap.org/ticket/1022
http://trac.openstreetmap.org/ticket/1023
http://trac.openstreetmap.org/ticket/1024
http://trac.openstreetmap.org/ticket/1040


/ Grant





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