asyncio 学习

1.协程
协程函数: 定义形式为 async def 的函数;
协程对象: 调用 协程函数 所返回的对象。

2.创建任务
asyncio.create_task(coro, *, name=None)
将 coro 协程 封装为一个 Task 并调度其执行。返回 Task 对象。

3.并发运行任务
asyncio.gather(*aws, return_exceptions=False)
并发 运行 aws 序列中的 可等待对象。

import asyncio
import time
import json


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


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

#     await say_after(1, 'hello')
#     await say_after(2, 'world')

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


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

#     task1 = asyncio.create_task(say_after(1, 'hello'))
#     task2 = asyncio.create_task(say_after(2, 'world'))

#     await task1
#     await asyncio.sleep(1)
#     await task2

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


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

    task1 = asyncio.create_task(say_after(1, 'hello'))
    task2 = asyncio.create_task(say_after(2, 'world'))

    await asyncio.gather(task1, asyncio.sleep(1), task2)

    tasks = list()
    for i in range(1, 100):
        task = asyncio.create_task(say_after(2, f'hello{i}'))
        tasks.append(task)

    await asyncio.gather(*tasks)

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


asyncio.run(main())

参考官方文档：https://docs.python.org/zh-cn/3/library/asyncio-task.html
如何使用 asyncio 限制协程的并发数: https://www.cnblogs.com/kcxg/p/15107785.html