[OSM-talk] Mapnik tileset coherency issues

[Christopher Schmidt]

On Thu, Oct 18, 2007 at 05:38:30PM -0400, Andrew MacKinnon wrote:
> On 10/18/07, Tom Hughes <tom at compton.nu> wrote:
> > > I'm not convinced by the need for a queue for the high zoom tiles - I
> > > think we should either render straight away or not at all. I think the
> > > probability of any individual high level tile being re-visited is quite low.
> >
> > Umm.... Without the queue lots of people would just get blank space
> > on the map. At peak times there is no way we can render all the needed
> > tiles on demand and if they're not queued then they will still not be
> > there the next time somebody looks at that area.
> 
> http://labs.metacarta.com/osm/, an alternative OSM slippy map, seems
> to be able to render tiles in real time with quite acceptable
> performance. 

1. Super-fast machine donated to a university by Intel.
2. Super-low usage in comparison to OSM -- that site serves something
   like 1000 tiles a day compared to OSM's millions!
3. If a lot of people view it immediately after I've viewed the cache,
   it causes tons of problems -- the load average got to 120 before I
   had to kill Apache eventually on Wednesday morning.

It's nice to be able to have it as a tool for visualizing the most up to
date data for developers, but it's not a tenable solution for OSM's main
map.

> perhaps rendering tiles in real time at off-peak times, and putting
> them into a queue at peak times.

That's already the case -- there just *are* no off-peak times anymore.

Regards,
-- 
Christopher Schmidt
MetaCarta