[MapProxy] Benchmarking Mapnik seeding performance

[Paul Norman]

I'm doing some investigations of metatile settings with MapProxy, and
wanted to run my method by the list in case anyone can spot problems
with it.

I have mapnik source pointing at Mapnik XML, and a file cache based on
it, saving in TMS directory layout. The metatile size is adjusted
depending on what I'm testing. For a seed file, I'm seeding that cache
to z8 with mapproxy-seed, adjusting the parallelism with -c.

A couple of potential problems I already know about are

- Mapnik has problems with images over 16384px in any dimension, so the
biggest metatiles that are power of two are 32x32
- inode limitations can be a problem for higher zooms, but aren't an
issue at z8, or even z12.

Are there any others that I might hit, particularly any unique to
MapProxy? I recall hearing that MapProxy needs to reload part of Mapnik
for each tile it renders, but found nothing documenting this and have no
idea if it's true.

[Oliver Tonnhofer]

Hi Paul,

Are there any others that I might hit, particularly any unique to MapProxy? I recall hearing that MapProxy needs to reload part of Mapnik for each tile it renders, but found nothing documenting this and have no idea if it's true.

Yes this is true (for each meta tile of course).

Reusing the loaded Mapnik objects was disabled because it caused trouble when they were used by multiple processes. It's been a while and I'm not sure what the actual issues were. There is definitely room for improvements in MapProxy.


Regards,
Oliver