• Igor Davydenko
• Python & React.js developer at Ezhome Inc.
• From Kyiv, Ukraine
• Love Python 3, asyncio & aio stack
• Personal Site
• @ GitHub
• @ Twitter

• Twisted
• Tornado
• Eventlet
• Gevent
• …

• Everything started back Dec 2012 with PEP 3156
• asyncio has been included into standard library 2 years ago, in Python 3.4
• Min version to use asyncio: Python 3.3
• asyncio has been ported to Python 2 as trollius

• Pluggable event-loop with various system-specific implementations
• Transport and protocol abstractions
• Concrete support of TCP, UDP, SSL, subprocess pipes, delayed calls, and others
• A Future class adapted for use with event loop
• Coroutines and tasks based on yield from
• Cancellation support for Futures and coroutines
• And few other features

import asyncio
import random

@asyncio.coroutine
def hello_world(idx):
    yield from asyncio.sleep(random.uniform(.1, .5))
    print('Hello, world!', idx)

loop = asyncio.get_event_loop()
loop.run_until_complete(asyncio.wait([hello_world(idx) for idx in range(10)]))
loop.close()

Hello, world! 2
Hello, world! 9
Hello, world! 4
Hello, world! 5
Hello, world! 1
Hello, world! 3
Hello, world! 8
Hello, world! 7
Hello, world! 6
Hello, world! 0

import random
import time

def hello_world(idx):
    time.sleep(random.uniform(.1, .5))
    print('Hello, world!', idx)

[hello_world(idx) for idx in range(10)]

Hello, world! 0
Hello, world! 1
Hello, world! 2
Hello, world! 3
Hello, world! 4
Hello, world! 5
Hello, world! 6
Hello, world! 7
Hello, world! 8
Hello, world! 9

import asyncio

@asyncio.coroutine

yield from asyncio.sleep(...)

loop = asyncio.get_event_loop()

asyncio.wait([...])

loop.run_until_complete(...)

loop.close()

• Again everything started with PEP, PEP 492
• First draft: last April
• Received warm greetings from community
• Included in Python 3.5, last September

@asyncio.coroutine
def hello_world(idx):
    yield from asyncio.sleep(random.uniform(.1, .5))
    print('Hello, world!', idx)

async def hello_world(idx):
    yield from asyncio.sleep(random.uniform(.1, .5))
    print('Hello, world!', idx)

async def hello_world(idx):
    await asyncio.sleep(random.uniform(.1, .5))
    print('Hello, world!', idx)

Before

with (yield from engine) as conn:
    yield from conn.excute(...)

After

async with engine.acquire() as conn:
    await conn.execute(...)

Before

for item in (yield from conn.execute(...)):
    ...

After

async for item in conn.execute(...):
    ...

• aiohttp
  HTTP client/server for asyncio.
• aiopg
  PostgreSQL client for asyncio. With SQLAlchemy core support.
• aioredis
  Redis client for asyncio.
• aio…
  There is also a clients for MySQL, Memcached, ZMQ, AMQP, ...

• Asphalt
  asyncio based microframework for network oriented applications
• autobahn
  WebSocket and WAMP in Python for Twisted and asyncio
• API Hour
  Write efficient network daemons (HTTP, SSH...) with ease
• nautilus
  A framework for building event-driven microservice applications

• muffin
  Fast, simple and asyncronous web-framework for Python 3
• Growler
  Micro web framework built atop of asyncio
• albatross3
  A modern, fast, simple async python3 web framework
• Kyōkai
  Fast asynchronous Python server-side web microframework

• curio
  The coroutine concurrency library
• aioh2
  HTTP/2 implementation with hyper-h2 on Python 3 asyncio
• aiotg
  Framework for building Telegram bots
• aiofiles
  File support for asyncio
• aioredx
  Pythonic redux
• Agent
  Async generators for humans
• twtxt
  Decentralised, minimalist microblogging service for hackers

• Why to write Python, if node.js is faster?
• Why to write Python, if Go is faster?
• Is asyncio slow?

• MagicStack/uvloop
• https://magic.io/blog/uvloop-blazing-fast-python-networking/
• pip install uvloop
• Fast, drop-in replacement of the built-in asyncio event loop
• Implemented in Cython and uses libuv under the hood
• uvloop makes asyncio 2-4x faster

aiohttp + Gunicorn

gunicorn -b 0.0.0.0:8000 -k aiohttp.worker.GunicornUVLoopWebWorker -w 5 \
path.to.app:app

asyncio

import asyncio
import uvloop
asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())

• MagicStack/asyncpg
• http://magic.io/blog/asyncpg-1m-rows-from-postgres-to-python/
• Database interface library designed specifically for PostgreSQL and Python/asyncio
• 3x faster than psycopg2 (and its asyncio variant – aiopg)

async def run():
    conn = await asyncpg.connect(user='user', password='password',
                                 database='database', host='127.0.0.1')
    values = await conn.fetch('SELECT * FROM mytable')
    await conn.close()

• All changes to asyncio in 3.6 will be backported to 3.5
• Main changes related to support of custom loop as uvloop

• Efficient guards using versionned dictionaries to check if something was modified
• Guards are used to decide if the specialized bytecode of a function can be used or not
• fatoptimizer project
• fat module