How Does Python\'s Asyncio Achieve Asynchronous Programming?

How does asyncio work?

Asynchronous programming in Python is made possible by the asyncio module, which leverages the capabilities of generators and yield from.

Coroutines with Async and Await

Asyncio utilizes coroutines, which are functions that can be paused and resumed while running. In Python, coroutines are defined using the async def keyword, and they utilize the await keyword to yield from other coroutines.

Futures and Tasks

Futures are objects that implement the __await__() method and hold a state and result. Tasks are special futures that wrap around coroutines and interact with both the inner and outer coroutines.

IO Implementation

Asynchronous IO is achieved through the use of event loops and the select function, provided by the underlying operating system. Event loops manage a queue of tasks and coordinate their execution.

When a coroutine awaits an IO operation, such as receiving data from a socket, the corresponding task registers the socket with the select function. When the IO operation completes, the select function wakes up the event loop, which in turn notifies the task and sets the result of the future associated with the socket to done.

This sequence of events allows asyncio tasks to pause their execution while waiting for IO operations, and the event loop seamlessly switches to other waiting tasks, ensuring optimal resource utilization.

The above is the detailed content of How Does Python's Asyncio Achieve Asynchronous Programming?. For more information, please follow other related articles on the PHP Chinese website!