Python 异步编程 asyncio 与 aiohttp 实战

Python 异步编程 asyncio 与 aiohttp 实战

asyncio 是 Python 异步 I/O 框架，适合 IO 密集型任务。

1. 基本用法

import asyncio



async def say_hello():

    print("Hello")

    await asyncio.sleep(1)

    print("World")



asyncio.run(say_hello())

2. 并发任务

async def main():

    tasks = [asyncio.create_task(say_hello()) for _ in range(3)]

    await asyncio.gather(*tasks)

3. aiohttp 异步 HTTP 请求

import aiohttp



async def fetch(session, url):

    async with session.get(url) as response:

        return await response.text()



async def main():

    async with aiohttp.ClientSession() as session:

        results = await asyncio.gather(

            fetch(session, "http://httpbin.org/get"),

            fetch(session, "http://httpbin.org/ip")

        )

        print(results)

4. 并发控制（Semaphore）

sem = asyncio.Semaphore(10)



async def bounded_fetch(session, url):

    async with sem:

        return await fetch(session, url)

异步爬虫比多线程更轻量，可大幅提升 IO 密集型应用性能。