What's new in Tornado 6.4.0

Nov 28, 2023

General Changes


- Python 3.12 is now supported. Older versions of Tornado will work on Python 3.12 but may log
  deprecation warnings.

Deprecation Notices

.IOLoop.add_callback_from_signal is suspected to have been broken since Tornado 5.0 and will be removed in version 7.0. Use asyncio.loop.add_signal_handler instead.
The client_secret argument to .OAuth2Mixin.authorize_redirect is deprecated and will be removed in Tornado 7.0. This argument has never been used and other similar methods in this module don't have it.
.TwitterMixin is deprecated and will be removed in the future.

tornado.auth


- The ``client_secret`` argument to `.OAuth2Mixin.authorize_redirect` is deprecated and will be
  removed in Tornado 7.0. This argument has never been used and other similar methods in this module
  don't have it.
- `.TwitterMixin` is deprecated and will be removed in the future.

``tornado.autoreload``

Autoreload can now be used when the program is run as a directory rather than a file or module.
New CLI flag --until-success re-runs the program on any failure but stops after the first successful run.

tornado.concurrent


- Fixed reference cycles that could lead to increased memory usage.

``tornado.escape``
~~~~~~~~~~~~~~~~~~

- Several methods in this module now simply pass through to their equivalents in the standard
  library.

``tornado.gen``
~~~~~~~~~~~~~~~

- This module now holds a strong reference to all running `asyncio.Task` objects it creates. This
  prevents premature garbage collection which could cause warnings like "Task was destroyed but it
  is pending!".

``tornado.ioloop``
~~~~~~~~~~~~~~~~~~

- `.IOLoop.add_callback_from_signal` is suspected to have been broken since Tornado 5.0 and will be
  removed in version 7.0.  Use `asyncio.loop.add_signal_handler` instead.
- The type annotation for `.IOLoop.run_in_executor` has been updated to match the updated signature
  of `asyncio.loop.run_in_executor`.
- Fixed reference cycles that could lead to increased memory usage.

``tornado.locale``
~~~~~~~~~~~~~~~~~~

- `.format_timestamp` now supports "aware" datetime objects.

``tornado.platform.asyncio``

The shutdown protocol for .AddThreadSelectorEventLoop now requires the use of asyncio.run or asyncio.loop.shutdown_asyncgens to avoid leaking the thread.
Introduced .SelectorThread class containing the core functionality of .AddThreadSelectorEventLoop.
The close() method of .AddThreadSelectorEventLoop is now idempotent.

tornado.web


- `.StaticFileHandler.get_modified_time` now supports "aware" datetime objects and the default
  implementation now returns aware objects.

``tornado.websocket``

Unclosed client connections now reliably log a warning. Previously the warning was dependent on garbage collection and whether the ping_interval option was used.
The subprotocols argument to .WebSocketClientConnection now defaults to None instead of an empty list (which was mutable and reused)