Introduction

In Python, asyncio is a powerful asynchronous programming library for writing highly concurrent asynchronous programs. In asyncio, Future and Task are two core concepts used to manage the state and execution of asynchronous operations. This article will introduce Future and Task in asyncio, including their concepts, usage, and practical application scenarios, with plenty of example code.

Future

A Future is an object representing the result of an asynchronous operation that may be completed in the future. In asyncio, you can create a Future object using asyncio.Future(), and then wrap an asynchronous operation into a Task object using asyncio.ensure_future() or asyncio.create_task(), ultimately obtaining the result of the asynchronous operatoin.

1. Creating a Future Object

Here is a simple example demonstrating how to use asyncio.Future() to create a Future object:

import asyncio

async def coro():
    await asyncio.sleep(1)
    return "Hello, Future!"

future = asyncio.Future()

In this example, a coroutine function coro is created, and then a Future object is created using asyncio.Future().

2. Wrapping a Future in to a Task

Besides using a Future object directly, we can also wrap an asynchronous operation into a Task object using asyncio.ensure_future() or asyncio.create_task(), making it easier to manage asynchronous operations.

task = asyncio.ensure_future(coro())
# Or
task = asyncio.create_task(coro())

3. Retrieving the Future Result

Once the asynchronous operation is complete, you can use the add_done_callback() method or the await keyword to obtain the result of the Future object.

def callback(fut):
    print("Future result:", fut.result())

future.add_done_callback(callback)

# Or use the await keyword

Task

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