[Twisted-Python] Does the default session expiry work?

I'm using twisted 8.2 and (after reading glyph's latest "Twisted in 60 seconds" entry), I've realized that my sessions never expire. I never added any session expiration code, but I thought that the default code expires after 15 minutes. In the below example, I modified twisted\web\server to make Session.sessionTimeout be 30 seconds (I also put a print statement in Session's ctor, as the log shows), then did two GETs separated by more than 30 seconds. As the log shows, it looks like the exact same session uid is being returned. I would expect it to be deleted by Session.expire, since time - lastModifiedTime > 30. Am I missing something? import sys from twisted.web import server, static from twisted.web.resource import Resource from twisted.web.server import Session, NOT_DONE_YET from twisted.internet import reactor, ssl from twisted.python import log class TestSessionResource(Resource): isLeaf = True def render_GET(self, request): session = request.getSession() print session.sessionTimeout print session.uid print session return "<html><body><p>Session Test</p></body></html>" root = TestSessionResource() reactor.listenTCP(9000, server.Site(root)) log.startLogging(sys.stdout) reactor.run() 2010-03-02 12:16:49-0600 [-] Log opened. 2010-03-02 12:16:52-0600 [HTTPChannel,0,127.0.0.1] making a new session!!! 2010-03-02 12:16:52-0600 [HTTPChannel,0,127.0.0.1] 30 2010-03-02 12:16:52-0600 [HTTPChannel,0,127.0.0.1] 338e4aa450f671b2f0115513737e643b 2010-03-02 12:16:52-0600 [HTTPChannel,0,127.0.0.1] <twisted.web.server.Session instance at 0x01042AD0> 2010-03-02 12:16:52-0600 [HTTPChannel,0,127.0.0.1] 127.0.0.1 - - [02/Mar/2010:18:16:51 +0000] "GET / HTTP/1.1" 200 45 "-" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.0.249.89 Safari/532.5" 2010-03-02 12:16:52-0600 [HTTPChannel,0,127.0.0.1] 30 2010-03-02 12:16:52-0600 [HTTPChannel,0,127.0.0.1] 338e4aa450f671b2f0115513737e643b 2010-03-02 12:16:52-0600 [HTTPChannel,0,127.0.0.1] <twisted.web.server.Session instance at 0x01042AD0> 2010-03-02 12:16:52-0600 [HTTPChannel,0,127.0.0.1] 127.0.0.1 - - [02/Mar/2010:18:16:51 +0000] "GET /favicon.ico HTTP/1.1" 200 45 "-" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.0.249.89 Safari/532.5" 2010-03-02 12:17:45-0600 [HTTPChannel,0,127.0.0.1] 30 2010-03-02 12:17:45-0600 [HTTPChannel,0,127.0.0.1] 338e4aa450f671b2f0115513737e643b 2010-03-02 12:17:45-0600 [HTTPChannel,0,127.0.0.1] <twisted.web.server.Session instance at 0x01042AD0> 2010-03-02 12:17:45-0600 [HTTPChannel,0,127.0.0.1] 127.0.0.1 - - [02/Mar/2010:18:17:44 +0000] "GET / HTTP/1.1" 200 45 "-" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.0.249.89 Safari/532.5" 2010-03-02 12:17:45-0600 [HTTPChannel,0,127.0.0.1] 30 2010-03-02 12:17:45-0600 [HTTPChannel,0,127.0.0.1] 338e4aa450f671b2f0115513737e643b 2010-03-02 12:17:45-0600 [HTTPChannel,0,127.0.0.1] <twisted.web.server.Session instance at 0x01042AD0> 2010-03-02 12:17:45-0600 [HTTPChannel,0,127.0.0.1] 127.0.0.1 - - [02/Mar/2010:18:17:44 +0000] "GET /favicon.ico HTTP/1.1" 200 45 "-" "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.0.249.89 Safari/532.5"