The document discusses the future of asynchronous I/O in Python. It introduces PEP 3156 and the new asyncio module in Python 3.4 as a standard library for asynchronous I/O. It describes how asyncio (called Tulip in the presentation) provides primitives like event loops, transports, protocols and coroutines to build asynchronous applications and frameworks in a pluggable, coroutine-friendly way. It provides examples of using Tulip to run asynchronous tasks and build an echo server.

1. Saúl Ibarra Corretgé
The future of async i/o in
Python
Amsterdam Python Meetup Group, 2nd October 2013
Thursday, October 3, 2013

2. __repr__(self)
@saghul
I work on VoIP and Real Time
Communications (RTC) stuff
Python is my (main) hammer
Thursday, October 3, 2013

3. while True
libuv, pyuv
tulip, rose
tornado-pyuv
twisted-pyuv
uvent
evergreen
Thursday, October 3, 2013

4. help(async_io)
Blocking Is Bad (TM)
Threads → overhead
i/o multiplexors: “Iʼll let you know
when you can write”
Windows: “Iʼll let you know when
Iʼm done writing”
Thursday, October 3, 2013

5. import platform
Thursday, October 3, 2013

6. raise NotImplementedError
“Included batteries donʼt fit”
asyncore, asyncchat
Many frameworks
Twisted
Tornado
Eventlet / Gevent
...
Thursday, October 3, 2013

7. Thursday, October 3, 2013

8. class MyLoop
Almost no reusable code between
frameworks
Multiple equivalent event loop
implementations
Multiple protocol implementations
HTTP, anyone?
Thursday, October 3, 2013

9. import tulip
Thursday, October 3, 2013

10. import tulip
PEP-3156: Async I/O support rebooted
A set of components / primitives for async i/o
Python >= 3.3
First version to ship with Python 3.4
(Boring) name for stdlib: asyncio
Thursday, October 3, 2013

11. dir(tulip)
Pluggable event loop
Easy to build adapters
Transport / protocol abstractions
Inspired by Twisted
High-level scheduler based on PEP-380 (yield
from), Futures, Tasks
Coroutine friendly Queue, Lock, Event, ...
Thursday, October 3, 2013

12. print(“hello world”)
from tulip import events
def test():
print("Hello Tulip!")
loop.stop()
loop = events.new_event_loop()
loop.call_soon(test)
loop.run_forever()
Thursday, October 3, 2013

13. from tulip import tasks
from tulip import events, tasks
@tasks.coroutine
def sleeper(name, n):
while True:
yield from tasks.sleep(n, loop=loop)
print('Hello from', name)
loop = events.new_event_loop()
t1 = tasks.async(sleeper('Task1', 1), loop=loop)
t2 = tasks.async(sleeper('Task2', 2), loop=loop)
loop.run_forever()
Thursday, October 3, 2013

14. echo echo echo
import os
from tulip import events, protocols
class EchoProtocol(protocols.Protocol):
def connection_made(self, transport):
print('Client connected')
self.transport = transport
def data_received(self, data):
print('Received data:',data)
self.transport.write(data)
def connection_lost(self, exc):
print('Connection closed', exc)
def Factory():
return EchoProtocol()
loop = events.new_event_loop()
f = loop.start_serving(Factory, '127.0.0.1', int(os.getenv('PORT') or 1234))
sockets = loop.run_until_complete(f)
print('Server started')
loop.run_forever()
Thursday, October 3, 2013

15. print(sys.modules)
People already started implementing stuff
with Tulip
Redis client, websockets, Gunicorn
worker, ...
https://code.google.com/p/tulip/wiki/
ThirdParty
Make your next library Tulip compatible!
(bonus points if it has a nice flower name)
Thursday, October 3, 2013

16. import __future__
All current frameworks would
integrate with Tulip, directly or using
an adapter
Reusable protocols
Integration with Twistedʼs Deferred
...
Thursday, October 3, 2013

17. help()
Checkout the code
http://code.google.com/p/tulip/
Join the mailing list
https://groups.google.com/forum/?
fromgroups#!forum/python-tulip
Thursday, October 3, 2013

18. input(‘Questions?’)
bettercallsaghul.com
Thursday, October 3, 2013

19. We are hiring!
VoIP, Instant Messaging, Presence
Python, C
PyQt, PyObjC
Windows, Linux, OSX
...
http://ag-projects.com
Thursday, October 3, 2013