asyncio 初体验

第一个程序

import asyncio

async def first():
    print("first")

result=first()
print(result)
asyncio.run(result)

await + 可等待对象（协程对象，future，task）

task对象-在事件循环中添加多个任务

import asyncio

async def f():
    print(1)
    await asyncio.sleep(1)
    print(2)
    return 'f'

async def main():
    print("main start")
    task_list=[
        asyncio.create_task(f(),name='f1'),
        asyncio.create_task(f(),name='f2')
    ]
    done,pending=await asyncio.wait(task_list,timeout=None) #done是集合，返回值对象
    print(done)

asyncio.run(main())

future对象-task类的基类

不支持协程转换为协程可执行的方法

import asyncio
import time


def f():
    print(1)
    time.sleep(2)
    print(2)
    return "f"

async def main():
    loop=asyncio.get_running_loop()
    fus=[loop.run_in_executor(None,f),
    loop.run_in_executor(None,f)] #None 可以传入线程池和进程池对象

    result=await asyncio.wait(fus)
    print(result)

asyncio.run(main())

例子

import asyncio
import requests


async def download(url):
    loop = asyncio.get_event_loop()
    fut=loop.run_in_executor(None,requests.get,url)
    res=await fut
    return res


urls=['u1','u2']
tasks=[
    download(url) for url in urls
]

asyncio.run(asyncio.wait(tasks))