Tornado

6.5.5 · active · verified Sat Mar 28

Tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed. It enables scalable, non-blocking network I/O, making it ideal for applications requiring long-lived connections, such as long polling and WebSockets. The current version is 6.5.5, with a release cadence of approximately every few months.

Warnings

breaking IOLoop.add_callback_from_signal is deprecated and will be removed in Tornado 7.0. Use asyncio.loop.add_signal_handler instead.
Fix: Replace IOLoop.add_callback_from_signal with asyncio.loop.add_signal_handler.
deprecated The client_secret argument to OAuth2Mixin.authorize_redirect is deprecated and will be removed in Tornado 7.0.
Fix: Remove the client_secret argument from OAuth2Mixin.authorize_redirect calls.
gotcha Tornado is not thread-safe. Ensure that Tornado objects are not accessed from multiple threads simultaneously.
Fix: Use IOLoop.add_callback to schedule callbacks on the main thread.

Install

pip install tornado Install Tornado

Imports

RequestHandler
```
from tornado.web import RequestHandler
```
Ensure correct import path to avoid ImportError
Application
```
from tornado.web import Application
```
Ensure correct import path to avoid ImportError
IOLoop
```
from tornado.ioloop import IOLoop
```
Ensure correct import path to avoid ImportError

Quickstart

A simple Tornado application that responds with 'Hello, world' to GET requests on the root URL.

import asyncio
from tornado.web import Application, RequestHandler
from tornado.ioloop import IOLoop

class MainHandler(RequestHandler):
    def get(self):
        self.write('Hello, world')

def make_app():
    return Application([
        (r'/', MainHandler),
    ])

async def main():
    app = make_app()
    app.listen(8888)
    await asyncio.Event().wait()

if __name__ == '__main__':
    asyncio.run(main())

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