asyncio.rst

tornado.platform.asyncio --- Bridge between asyncio and Tornado

.. module:: tornado.platform.asyncio

.. versionadded:: 3.2

This module integrates Tornado with the asyncio module introduced in Python 3.4 (and available as a separate download for Python 3.3). This makes it possible to combine the two libraries on the same event loop.

Most applications should use AsyncIOMainLoop to run Tornado on the default asyncio event loop. Applications that need to run event loops on multiple threads may use AsyncIOLoop to create multiple loops.

Note

Tornado requires the ~asyncio.BaseEventLoop.add_reader family of methods, so it is not compatible with the ~asyncio.ProactorEventLoop on Windows. Use the ~asyncio.SelectorEventLoop instead.

.. py:class:: AsyncIOMainLoop

    ``AsyncIOMainLoop`` creates an `.IOLoop` that corresponds to the
    current ``asyncio`` event loop (i.e. the one returned by
    ``asyncio.get_event_loop()``).  Recommended usage::

        from tornado.platform.asyncio import AsyncIOMainLoop
        import asyncio
        AsyncIOMainLoop().install()
        asyncio.get_event_loop().run_forever()

.. py:class:: AsyncIOLoop

    ``AsyncIOLoop`` is an `.IOLoop` that runs on an ``asyncio`` event loop.
    This class follows the usual Tornado semantics for creating new
    ``IOLoops``; these loops are not necessarily related to the
    ``asyncio`` default event loop.  Recommended usage::

        from tornado.ioloop import IOLoop
        IOLoop.configure('tornado.platform.asyncio.AsyncIOLoop')
        IOLoop.instance().start()

    Each ``AsyncIOLoop`` creates a new ``asyncio.EventLoop``; this object
    can be accessed with the ``asyncio_loop`` attribute.

.. py:function:: to_tornado_future

   Convert an ``asyncio.Future`` to a `tornado.concurrent.Future`.

   .. versionadded:: 4.1

.. py:function:: to_asyncio_future

   Convert a `tornado.concurrent.Future` to an ``asyncio.Future``.

   .. versionadded:: 4.1