asyncio基础用法

说明：需要Python 3.7+

1、并发运行两个coroutine，写法一： 用Task

import asyncio
import time

async def say_after(delay, what):
    await asyncio.sleep(delay)
    print(what)

async def main():
    task1 = asyncio.create_task(
        say_after(1, 'hello'))

    task2 = asyncio.create_task(
        say_after(2, 'world'))

    print(f"started at {time.strftime('%X')}")

    # Wait until both tasks are completed (should take around 2 seconds.)
    r1 = await task1
    r2 = await task2
    print(f"finished at {time.strftime('%X')}")
    print("result: ", r1, r2)

asyncio.run(main())

运行时间：2s

1、并发运行两个coroutine，写法二： 用 gather

import asyncio
import time

async def say_after(delay, what):
    await asyncio.sleep(delay)
    print(what)

async def main():
    print(f"started at {time.strftime('%X')}")

    result = await asyncio.gather(say_after(1, 'hello'), say_after(2, 'world'))

    print(f"finished at {time.strftime('%X')}")
    print("result: ", result)

asyncio.run(main())

运行时间：2s

说明：

一、使用async def 将方法变成协程，用await修饰有阻塞的操作

二、await后可跟三种类型: 协程, 任务 和 Future.