The asyncio module in Python

The asyncio module in Python provides support for writing concurrent, single-threaded programs using co-routines. It is available only in Python 3.

A co-routine using the asyncio module is one that uses either of the following approaches:

• Using the async def statement for defining functions

• Being decorated using the @asyncio.coroutine expression

Generator-based co-routines use the second technique, and they yield from expressions.

Co-routines created using the first technique typically use the await <future> expression to wait for the future to be completed.

Co-routines are scheduled for execution using an event loop, which connects the objects and schedules them as tasks. Different types of event loop are provided for different operating systems.

The following code rewrites our earlier example of a simple cooperative multitasking scheduler to use the asyncio module:

# asyncio_tasks.py
import asyncio

def number_generator(m, n):
    """ A number generator co-routine...