CherryPy Sessions on GAE

My only confirmed regular reader, Sal, notified me of a potential problem with using CherryPy on GAE which stems from the multi-threaded nature of CherryPy and the single threaded ways of GAE. It was first noticed in trying to take advantage of the cherrypy.session facilities. In short, you can use cherrypy.session to store session values in the memcached backend, but I am still trying to determine whether the session information is deleted from the store, even on a cherrypy.session.delete() call. and it seems to work just fine, but I have to confirm a few things regarding the session cookie left behind on the browser.

The original comment is here, for the curious.

If you would still need sessions and just can’t wait for the bugs to be ironed out, here is how you go about using cherrypy.session. In your main.py:

from google.appengine.api import memcache
# patch sys memcache module locations to use GAE memcache
sys.modules['memcache'] = memcache

You’ll need these configuration options defined and applied to the tree.mount() in the main():

cf = {"/":{'tools.sessions.on':  True,
            'tools.sessions.storage_type': "memcached",
            'tools.sessions.servers': ['memcached://'],
            'tools.sessions.name': 'hello_gb_session_id',
            'tools.sessions.clean_thread': True,
            'tools.session.timeout': 10, # ten minute session timeout, not sure if this works
            }}
  app = cherrypy.tree.mount(MyClass(),config=cf)

Then in your methods you can get and set session variables at will like so:

def index(self):
    cherrypy.session['msg'] = "Hello World!"
    return cherrypy.session['msg']