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tornado.platform.twisted — Bridges between Twisted and Tornado

Bridges between the Twisted reactor and Tornado IOLoop.

This module lets you run applications and libraries written for Twisted in a Tornado application. It can be used in two modes, depending on which library’s underlying event loop you want to use.

This module has been tested with Twisted versions 11.0.0 and newer.

Twisted on Tornado

class tornado.platform.twisted.TornadoReactor[source]

Twisted reactor built on the Tornado IOLoop.

TornadoReactor implements the Twisted reactor interface on top of the Tornado IOLoop. To use it, simply call install at the beginning of the application:

import tornado.platform.twisted
from twisted.internet import reactor

When the app is ready to start, call IOLoop.current().start() instead of

It is also possible to create a non-global reactor by calling tornado.platform.twisted.TornadoReactor(). However, if the IOLoop and reactor are to be short-lived (such as those used in unit tests), additional cleanup may be required. Specifically, it is recommended to call:


before closing the IOLoop.

Changed in version 5.0: The io_loop argument (deprecated since version 4.1) has been removed.


Install this package as the default Twisted reactor.

install() must be called very early in the startup process, before most other twisted-related imports. Conversely, because it initializes the IOLoop, it cannot be called before fork_processes or multi-process start. These conflicting requirements make it difficult to use TornadoReactor in multi-process mode, and an external process manager such as supervisord is recommended instead.

Changed in version 5.0: The io_loop argument (deprecated since version 4.1) has been removed.

Tornado on Twisted

class tornado.platform.twisted.TwistedIOLoop[source]

IOLoop implementation that runs on Twisted.

TwistedIOLoop implements the Tornado IOLoop interface on top of the Twisted reactor. Recommended usage:

from tornado.platform.twisted import TwistedIOLoop
from twisted.internet import reactor
# Set up your tornado application as usual using `IOLoop.instance`

Uses the global Twisted reactor by default. To create multiple TwistedIOLoops in the same process, you must pass a unique reactor when constructing each one.

Not compatible with tornado.process.Subprocess.set_exit_callback because the SIGCHLD handlers used by Tornado and Twisted conflict with each other.

See also tornado.ioloop.IOLoop.install() for general notes on installing alternative IOLoops.

Twisted DNS resolver

class tornado.platform.twisted.TwistedResolver[source]

Twisted-based asynchronous resolver.

This is a non-blocking and non-threaded resolver. It is recommended only when threads cannot be used, since it has limitations compared to the standard getaddrinfo-based Resolver and DefaultExecutorResolver. Specifically, it returns at most one result, and arguments other than host and family are ignored. It may fail to resolve when family is not socket.AF_UNSPEC.

Requires Twisted 12.1 or newer.

Changed in version 5.0: The io_loop argument (deprecated since version 4.1) has been removed.