[OSM-dev] Availability of slippy map during LinuxTag 2007

Jon Burgess jburgess777 at googlemail.com
Wed May 30 12:18:37 BST 2007

On 30/05/07, Sebastian Spaeth <Sebastian at sspaeth.de> wrote:
> Hash: SHA1
> Jon Burgess wrote:
> >> 1) When using the Mapnik layer a lot, we will get the tiles saying "Tile
> >> download limit reached for your IP". That is not exactly what we want to
> >> showcase.
> >> Can this limit be removed? At least for the duration of LinuxTag?
> > I have just disabled the 10k download limit for the mapnik tiles.
> I had filed a ticket because I found that limit too harsh.
> http://trac.openstreetmap.org/ticket/456
> Do we know if bandwidth is a problem with the tile box? What are the
> bottlenecks on that machine? There are apache modules like mod_cband
> that can limit bandwidth on a per IP/Netmask-base if that helps somewhat.

I think the original limit was implemented after it was found that
some people were spidering large numbers of tiles (100k+). This puts
an artifical load on the system since it causes many tiles to get
rendered even if they are never likely to get looked at again. This
slows down things for other people which are actively viewing the map.

I've been collecting some simple stats from the access blocks over the
past week. We typically serve around 1M tiles per day to a couple of
thousand different IPs with only 1 - 10 people hitting the 10k limit
on any day.

I think we do need to implement some limit. For fairness if nothing
else. I'd rather we serve tiles to thousands of people which are
actively viewing the map instead of a few that just that want an
off-line copy of a map of europe.

Maybe adding a throttle / rate limit or something like an unlimited
download via a different URL which could have a lower priority (maybe
only for users with a login only). We also need to encourage large
users to download the planet.osm file and do their own local rendering
if they are wanting very large numbers of tiles. I'm hoping to improve
the Mapnik docs on the wiki to make this easier for people to do.


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