[OSM-talk] instant rendering of new tiles in mapnik layer

[Jon Burgess]

I've just made some changes to the Mapnik layer tile server to generate
missing tiles on-the-fly. In most cases you should not see the 404 'more
tiles coming soon' tile being returned. 

This extra load may adversely effect the performance of tile so I have
placed some bounds on the maximum number of outstanding tiles. If this
limit is hit you will get the old 'more coming soon' tile again. This
might happen right now if you all rush at once to examine those zoom 18
tiles!

The data used to render the tiles is still from the latest planet.osm
dump so please do not expect any data that you have uploaded since
Wednesday to appear until after the next planet dump.

Re-rendering of existing tile is still done as a background process so
you may see stale data immediately after a new planet dump. I may extend
the live rendering to include these tiles too if the current setup works
well.

I'll be monitoring tile to ensure it doesn't get completely overloaded
and will switch back to the old scheme if there are any problems. Please
let me know if you see any performance issues with the mapnik layer
tiles.

	Jon