[OSM-dev] Apache + mapnik + mod_python problem

[Dane Springmeyer]

On Jun 27, 2010, at 9:59 AM, yvecai wrote:

> Hi all,
> I am currently using a setup similar to http://wiki.openstreetmap.org/wiki/Howto_real_time_tiles_rendering_with_mapnik_and_mod_python.
> 

A better setup would likely be mod_tile, which supports multi-threaded request handling and rendering, by loading up a mapnik map object per thread.

> The problem I have is that some tiles are properly rendered, but other are not, like in this example: http://yvecai.olympe-network.com/divers/Capture.png

That is because each request is likely generating a child thread that is trying to share the same mapnik map, which is not good behavior, unless your python code is deployed as multiprocess (rather than multithreaded). If you are interested in multiprocess deployment see mod_wsgi, run in daemon mode, with threads=1 and processes=N CPU

> It looks like the rendering is not 'finished', and this is also the case for a layer containing only hillshading from SRTM raster images (some tiles are simply missing).
> On the other and, the generate_tile.py script works OK to create the tiles on disk.

Right, because generate_tiles.py is also smart like mod_tile. It works by creating a mapnik map for each thread.

> 
> Please find attached the scripts used by mod_python and the apache config file.
> 
> Ubuntu 10.04, mapnik 0.7.1
> Apache/2.2.14 (Ubuntu) mod_python/3.3.1 Python/2.6.5 configured
> Yves
> <renderer.py><gen_tile.py><moi.conf>_______________________________________________
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