Tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed. By using non-blocking network I/O, Tornado can scale to tens of thousands of open connections, making it ideal for long polling, WebSockets, and other applications that require a long-lived connection to each user.
Tornado is listed in PyPI and can be installed with pip or easy_install. Tornado should run on any Unix-like platform, although for the best performance and scalability only Linux (with epoll) and BSD (with kqueue) are recommended for production deployment (even though Mac OS X is derived from BSD and supports kqueue, its networking performance is generally poor so it is recommended only for development use).
Tornado will also run on Windows, although this configuration is not officially supported and is recommended only for development use. The Tornado web framework and HTTP server together offer a full-stack alternative to WSGI.
While it is possible to use the Tornado web framework in a WSGI container (WSGIAdapter), or use the Tornado HTTP server as a container for other WSGI frameworks (WSGIContainer), each of these combinations has limitations and to take full advantage of Tornado the developer needs to use the Tornado’s web framework and HTTP server together.