What’s new in Tornado 2.2

Jan 30, 2012


  • Updated and expanded WebSocket support.

  • Improved compatibility in the Twisted/Tornado bridge.

  • Template errors now generate better stack traces.

  • Better exception handling in tornado.gen.

Security fixes

  • tornado.simple_httpclient now disables SSLv2 in all cases. Previously SSLv2 would be allowed if the Python interpreter was linked against a pre-1.0 version of OpenSSL.

Backwards-incompatible changes

  • tornado.process.fork_processes now raises SystemExit if all child processes exit cleanly rather than returning None. The old behavior was surprising and inconsistent with most of the documented examples of this function (which did not check the return value).

  • On Python 2.6, tornado.simple_httpclient only supports SSLv3. This is because Python 2.6 does not expose a way to support both SSLv3 and TLSv1 without also supporting the insecure SSLv2.

  • tornado.websocket no longer supports the older “draft 76” version of the websocket protocol by default, although this version can be enabled by overriding tornado.websocket.WebSocketHandler.allow_draft76.


  • SimpleAsyncHTTPClient no longer hangs on HEAD requests, responses with no content, or empty POST/PUT response bodies.

  • SimpleAsyncHTTPClient now supports 303 and 307 redirect codes.

  • tornado.curl_httpclient now accepts non-integer timeouts.

  • tornado.curl_httpclient now supports basic authentication with an empty password.


  • HTTPServer with xheaders=True will no longer accept X-Real-IP headers that don’t look like valid IP addresses.

  • HTTPServer now treats the Connection request header as case-insensitive.

tornado.ioloop and tornado.iostream

  • IOStream.write now works correctly when given an empty string.

  • IOStream.read_until (and read_until_regex) now perform better when there is a lot of buffered data, which improves peformance of SimpleAsyncHTTPClient when downloading files with lots of chunks.

  • SSLIOStream now works correctly when ssl_version is set to a value other than SSLv23.

  • Idle IOLoops no longer wake up several times a second.

  • tornado.ioloop.PeriodicCallback no longer triggers duplicate callbacks when stopped and started repeatedly.


  • Exceptions in template code will now show better stack traces that reference lines from the original template file.

  • {# and #} can now be used for comments (and unlike the old {% comment %} directive, these can wrap other template directives).

  • Template directives may now span multiple lines.



  • Updated to support the latest version of the protocol, as finalized in RFC 6455.

  • Many bugs were fixed in all supported protocol versions.

  • tornado.websocket no longer supports the older “draft 76” version of the websocket protocol by default, although this version can be enabled by overriding tornado.websocket.WebSocketHandler.allow_draft76.

  • WebSocketHandler.write_message now accepts a binary argument to send binary messages.

  • Subprotocols (i.e. the Sec-WebSocket-Protocol header) are now supported; see the WebSocketHandler.select_subprotocol method for details.

  • .WebSocketHandler.get_websocket_scheme can be used to select the appropriate url scheme (ws:// or wss://) in cases where HTTPRequest.protocol is not set correctly.

Other modules

  • tornado.auth.TwitterMixin.authenticate_redirect now takes a callback_uri parameter.

  • tornado.auth.TwitterMixin.twitter_request now accepts both URLs and partial paths (complete URLs are useful for the search API which follows different patterns).

  • Exception handling in tornado.gen has been improved. It is now possible to catch exceptions thrown by a Task.

  • tornado.netutil.bind_sockets now works when getaddrinfo returns duplicate addresses.

  • tornado.platform.twisted compatibility has been significantly improved. Twisted version 11.1.0 is now supported in addition to 11.0.0.

  • tornado.process.fork_processes correctly reseeds the random module even when os.urandom is not implemented.

  • tornado.testing.main supports a new flag --exception_on_interrupt, which can be set to false to make Ctrl-C kill the process more reliably (at the expense of stack traces when it does so).

  • tornado.version_info is now a four-tuple so official releases can be distinguished from development branches.