Tornado Web Server — Tornado 6.5.5 documentation
Tornado Web Server
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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.
Quick links
Current version: 6.5.5 (
download from PyPI
release notes
Source (GitHub)
Mailing lists:
discussion
and
announcements
Stack Overflow
Wiki
Hello, world
Here is a simple “Hello, world” example web app for Tornado:
import
asyncio
import
tornado
class
MainHandler
tornado
web
RequestHandler
):
def
get
self
):
self
write
"Hello, world"
def
make_app
():
return
tornado
web
Application
([
"/"
MainHandler
),
])
async
def
main
():
app
make_app
()
app
listen
8888
await
asyncio
Event
()
wait
()
if
__name__
==
"__main__"
asyncio
run
main
())
This example does not use any of Tornado’s asynchronous features; for
that see this
simple chat room
Threads and WSGI
Tornado is different from most Python web frameworks. It is not based
on
WSGI
, and it is
typically run with only one thread per process. See the
User’s guide
for more on Tornado’s approach to asynchronous programming.
While some support of WSGI is available in the
tornado.wsgi
module,
it is not a focus of development and most applications should be
written to use Tornado’s own interfaces (such as
tornado.web
directly instead of using WSGI.
In general, Tornado code is not thread-safe. The only method in
Tornado that is safe to call from other threads is
IOLoop.add_callback
. You can also use
IOLoop.run_in_executor
to
asynchronously run a blocking function on another thread, but note
that the function passed to
run_in_executor
should avoid
referencing any Tornado objects.
run_in_executor
is the
recommended way to interact with blocking code.
asyncio
Integration
Tornado is integrated with the standard library
asyncio
module and
shares the same event loop (by default since Tornado 5.0). In general,
libraries designed for use with
asyncio
can be mixed freely with
Tornado.
Installation
pip
install
tornado
Tornado is listed in
PyPI
and
can be installed with
pip
. Note that the source distribution
includes demo applications that are not present when Tornado is
installed in this way, so you may wish to download a copy of the
source tarball or clone the
git repository
as well.
Prerequisites
: Tornado 6.3 requires Python 3.9 or newer. The following
optional packages may be useful:
pycurl
is used by the optional
tornado.curl_httpclient
. Libcurl version 7.22 or higher is required.
pycares
is an alternative
non-blocking DNS resolver that can be used when threads are not
appropriate.
Platforms
: Tornado is designed for Unix-like platforms, with best
performance and scalability on systems supporting
epoll
(Linux),
kqueue
(BSD/macOS), or
/dev/poll
(Solaris).
Tornado will also run on Windows, although this configuration is not
officially supported or recommended for production use. Some features
are missing on Windows (including multi-process mode) and scalability
is limited (Even though Tornado is built on
asyncio
, which
supports Windows, Tornado does not use the APIs that are necessary for
scalable networking on Windows).
Documentation
This documentation is also available in
PDF and Epub formats
User’s guide
Introduction
Asynchronous and non-Blocking I/O
Coroutines
Queue
example - a concurrent web spider
Structure of a Tornado web application
Templates and UI
Authentication and security
Running and deploying
Web framework
tornado.web
RequestHandler
and
Application
classes
tornado.template
— Flexible output generation
tornado.routing
— Basic routing implementation
tornado.escape
— Escaping and string manipulation
tornado.locale
— Internationalization support
tornado.websocket
— Bidirectional communication to the browser
HTTP servers and clients
tornado.httpserver
— Non-blocking HTTP server
tornado.httpclient
— Asynchronous HTTP client
tornado.httputil
— Manipulate HTTP headers and URLs
tornado.http1connection
– HTTP/1.x client/server implementation
Asynchronous networking
tornado.ioloop
— Main event loop
tornado.iostream
— Convenient wrappers for non-blocking sockets
tornado.netutil
— Miscellaneous network utilities
tornado.tcpclient
IOStream
connection factory
tornado.tcpserver
— Basic
IOStream
-based TCP server
Coroutines and concurrency
tornado.gen
— Generator-based coroutines
tornado.locks
– Synchronization primitives
tornado.queues
– Queues for coroutines
tornado.process
— Utilities for multiple processes
Integration with other services
tornado.auth
— Third-party login with OpenID and OAuth
tornado.wsgi
— Interoperability with other Python frameworks and servers
tornado.platform.caresresolver
— Asynchronous DNS Resolver using C-Ares
tornado.platform.twisted
— Bridges between Twisted and Tornado
tornado.platform.asyncio
— Bridge between
asyncio
and Tornado
Utilities
tornado.autoreload
— Automatically detect code changes in development
tornado.concurrent
— Work with
Future
objects
tornado.log
— Logging support
tornado.options
— Command-line parsing
tornado.testing
— Unit testing support for asynchronous code
tornado.util
— General-purpose utilities
Frequently Asked Questions
Release notes
What’s new in Tornado 6.5.5
What’s new in Tornado 6.5.4
What’s new in Tornado 6.5.3
What’s new in Tornado 6.5.2
What’s new in Tornado 6.5.1
What’s new in Tornado 6.5.0
What’s new in Tornado 6.4.2
What’s new in Tornado 6.4.1
What’s new in Tornado 6.4.0
What’s new in Tornado 6.3.3
What’s new in Tornado 6.3.2
What’s new in Tornado 6.3.1
What’s new in Tornado 6.3.0
What’s new in Tornado 6.2.0
What’s new in Tornado 6.1.0
What’s new in Tornado 6.0.4
What’s new in Tornado 6.0.3
What’s new in Tornado 6.0.2
What’s new in Tornado 6.0.1
What’s new in Tornado 6.0
What’s new in Tornado 5.1.1
What’s new in Tornado 5.1
What’s new in Tornado 5.0.2
What’s new in Tornado 5.0.1
What’s new in Tornado 5.0
What’s new in Tornado 4.5.3
What’s new in Tornado 4.5.2
What’s new in Tornado 4.5.1
What’s new in Tornado 4.5
What’s new in Tornado 4.4.3
What’s new in Tornado 4.4.2
What’s new in Tornado 4.4.1
What’s new in Tornado 4.4
What’s new in Tornado 4.3
What’s new in Tornado 4.2.1
What’s new in Tornado 4.2
What’s new in Tornado 4.1
What’s new in Tornado 4.0.2
What’s new in Tornado 4.0.1
What’s new in Tornado 4.0
What’s new in Tornado 3.2.2
What’s new in Tornado 3.2.1
What’s new in Tornado 3.2
What’s new in Tornado 3.1.1
What’s new in Tornado 3.1
What’s new in Tornado 3.0.2
What’s new in Tornado 3.0.1
What’s new in Tornado 3.0
What’s new in Tornado 2.4.1
What’s new in Tornado 2.4
What’s new in Tornado 2.3
What’s new in Tornado 2.2.1
What’s new in Tornado 2.2
What’s new in Tornado 2.1.1
What’s new in Tornado 2.1
What’s new in Tornado 2.0
What’s new in Tornado 1.2.1
What’s new in Tornado 1.2
What’s new in Tornado 1.1.1
What’s new in Tornado 1.1
What’s new in Tornado 1.0.1
What’s new in Tornado 1.0
Index
Module Index
Search Page
Discussion and support
You can discuss Tornado on
the Tornado developer mailing list
, and report bugs on
the
GitHub issue tracker
. Links to additional
resources can be found on the
Tornado wiki
. New releases are
announced on the
announcements mailing list
Tornado is available under
the
Apache License, Version 2.0
This web site and all documentation is licensed under
Creative
Commons 3.0