gaepytz 2011b

A version of pytz that works well on Google App Engine.

pytz has a severe performance problem that impedes its usage on Google App Engine. This is caused because pytz.__init__ builds a list of available zoneinfos checking the entire zoneinfo database (which means: it tries to open hundreds of files). This is done in the module globals, so it is not easily avoidable. And it is far from ideal to do this in App Engine - app initialization becomes unacceptable if every time we import pytz it checks 500+ files.

In this alternative version, pytz is highly optimized for App Engine, following ideas from several recipes around:

• database files are not automatically reads when the module is imported

• the database files are loaded using zipimport to reduce number of files

• it uses memcache to cache already loaded zoneinfos

This results in almost unnoticeable load time and makes pytz usable on App Engine.