This document discusses the Tornado web server framework. It provides an overview of Tornado, including that it is a non-blocking and scalable web server that was used by FriendFeed and is now open-sourced by Facebook. It describes Tornado's architecture, which uses an IOLoop and callbacks instead of threads to remain asynchronous and non-blocking. An example "Hello World" application in Tornado is also provided. Performance comparisons show Tornado outperforming other frameworks like Node.js and Twisted.

1. TornadoRocking the Non-Blocking WebContact:Twitter: Kurtiss Hare, CTO & Co-Founder of playhaven.com@kurtiss

2. What is Tornado?Scalable, Non-blocking Web ServerPowered www.friendfeed.comNow open-sourced by Facebook after FF acquisition

3. Why Tornado?

4. Why Tornado?Paul Buchheit

5. Why Tornado?Don’tBePaul Buchheit

6. Why Tornado?Processor/Thread ModelCherryPy, Mod_WSGI, uWSGI, …Lightweight ThreadsGevent, Eventlet, …IOLoop/Callback ModelTornado, Cogen, …What are you trying to do?

7. Why Tornado?Trying to address the c10k problem?10,000 concurrent connectionsProcessor/thread is known to fall overTrying to enable real-time/long-polling, WebSockets?Different problem than handling many short-lived, pipelined requests.Want to extend your arsenal with a tool that addresses these problems?Tornado might be for you.

8. Tornado’s Architecture~2000 clientstornado.ioloop._polltornado.web.RequestHandlertornado.httpserver.HTTPServersocket.sockettornado.ioloop.IOStreamtornado.httpserver.HTTPConnectiontornado.web.ApplicationRouting/MVCtornado.ioloop

9. Tornado’s Architecturetornado.ioloop._pollEdge-triggered when possible (epoll/kqueue)Falls back on level triggered (select)Handles:Callback registrationNew connectionsConnections with new dataHeart of Tornado’s approach to c10k

10. Hello, worldimport tornado.httpserverimport tornado.ioloopimport tornado.webclass MainHandler(tornado.web.RequestHandler): def get(self): self.write("Hello, world")application = tornado.web.Application([ (r"/", MainHandler),])if __name__ == "__main__”: http_server = tornado.httpserver.HTTPServer(application) http_server.listen(8888) tornado.ioloop.IOLoop.instance().start()

11. Rocking the Non-Blockclass MainHandler(tornado.web.RequestHandler): @tornado.web.asynchronous def get(self): http = tornado.httpclient.AsyncHTTPClient() http.fetch("http://friendfeed-api.com/v2/feed/kurtiss", callback=self.async_callback(self.on_response)) def on_response(self, response): if response.error: raise tornado.web.HTTPError(500) json = tornado.escape.json_decode(response.body) self.write("Fetched " + str(len(json["entries"])) + " entries ”) self.finish()

12. Performance NotesSource: http://developers.facebook.com/blog/post/301

13. Performance NotesBetter ComparisonsNode.js – Tornado by 110% throughput [0]Twisted.Web – Tornado by 84% shorter average response time [1]Caveat Emptor, OK?http://nichol.as/benchmark-of-python-web-serversOf note, “Server Latency,” vs. gEvent, uWSGILikely due to CPU availabilityNothing beats a load test on your own environmentPlayHaven’s use is modest, but growing:<500 concurrent web requestsNo long polling … yet.[0] http://news.ycombinator.com/item?id=1089340[1] http://www.apparatusproject.org/blog/2009/09/twisted-web-vs-tornado-part-deux/

14. Let’s Code

15. Questions? Beer?