[Maposmatic-dev] File descriptor leak problem

[Thomas Petazzoni]

Hello,

The problem that is currently preventing us from announcing MapOSMatic,
and which is causing the regular unavailabilities of the service is a
file descriptor leak problem.

From the investigations Maxime and I conducted today, it seems like
Mapnik keeps the .shp (and related) files opened once the rendering is
terminated. We use such files for the grid and the administrative
boundary shape, one per page in multi-page renderings. So for a 50
pages multi-page rendering, there are about 104 (50*2 + 2 for the cover
+ 2 for the overview) shape files that remain open.

An option would be to move the rendering process into a separate Unix
process for every rendering, so that all resources (memory, file
descriptors, etc.) are cleaned up.

Another option would be to fix the problem itself, but it seems to be
within Mapnik internals and/or the Python API that does not provide the
way of telling Mapnik to release the resources it has taken.

Thomas
-- 
Thomas Petazzoni                http://thomas.enix.org
MapOSMatic                      http://www.maposmatic.org
Logiciels Libres à Toulouse     http://www.toulibre.org
Embedded Linux                  http://www.free-electrons.com