Tornado is a scalable, non-blocking web server and web application framework written in Python. It was developed for use by FriendFeed; the company was acquired by Facebook in 2009 and Tornado was open-sourced soon after.
Tornado is noted for its high performance. It tries to solve the C10k problem affecting other servers. The following table shows a benchmark test of Tornado against other Python-based servers:
Performance on AMD Opteron, 2.4 GHz, four cores
||Requests per second
||nginx, four frontends
||One single-threaded frontend