[OSM-dev] mapnik image export failures (and fixes?)

[Tom Hughes]

On 19/07/10 08:41, Frederik Ramm wrote:

> Mikel Maron wrote:
>> Since the export function is linked from the main site, imo we should
>> consider it a core service that should be available at some service
>> level. Personally, we use this feature often through Map Kibera.
>
> The Mapnik image export works by custom rendering your image, whereas
> the Osmarender image export, and also anything you do via
> openstreetmap.gryph.de/bigmap.cgi, works by stitching together
> individual tiles. If any of these work for you then they will be more
> reliable than the image export (the bigmap service will let you create a
> Perl script which you can then run at any time to update the image).

The critical point is that the mapnik export, like the export tab in 
general, was designed for one off manual use but people seem to have 
decided to script access to it and scrape maps from it.

Sure we could try and scale it by putting massive resources behind it, 
but as Frederik says, it's not really a very efficient way to do things.

For the record I did ask Jon where the load was falling when you asked 
about this on IRC precisely because if he had said it was CPU load then 
we might have been able to arrange for a dedicated server to run the export.

Unfortunately he said it's as much database as anything, and I don't 
really want to get into having to run a separate rendering database just 
for the export if we can avoid it.

Tom

-- 
Tom Hughes (tom at compton.nu)
http://compton.nu/