python aiohttp超时是针对单个TCP连接还是针对http请求？

Question

在 python aiohttp 中，我们可以在ClientSession 或（例如）session.get 中设置超时。 https://docs.aiohttp.org/en/stable/client_quickstart.html

假设我们这样做

async with aiohttp.ClientSession(timeout=<customized timeout>) as session: 
    async with session.get(<url1>): 
        xxx
    async with session.get(<url2>): 
        xxx

customized timeout 是针对整个async with aiohttp.ClientSession() 还是针对每个async with session.get？

Answer 1

超时适用于每个单独的请求；你可以像这样测试它：

import asyncio
import aiohttp
import random

async def main():
    timeout = aiohttp.ClientTimeout(total=3)
    async with aiohttp.ClientSession(timeout=timeout) as session:
        base_url = "http://httpbin.org/delay/%d"
        for i in range(10):
            url = base_url % random.randint(1, 5)
            try:
                async with session.get(url) as response:
                    data = await response.json()
                    print(f"step {i}, url {url}, status {response.status}, keys: {len(data)}")
            except asyncio.exceptions.TimeoutError:
                print(f"step {i}, url {url}, status timeout")

asyncio.run(main())

我的电脑上的结果：

step 0, url http://httpbin.org/delay/5, status timeout
step 1, url http://httpbin.org/delay/5, status timeout
step 2, url http://httpbin.org/delay/2, status 200, keys: 7
step 3, url http://httpbin.org/delay/4, status timeout
step 4, url http://httpbin.org/delay/4, status timeout
step 5, url http://httpbin.org/delay/3, status 200, keys: 7
step 6, url http://httpbin.org/delay/2, status 200, keys: 7
step 7, url http://httpbin.org/delay/3, status 200, keys: 7
step 8, url http://httpbin.org/delay/1, status 200, keys: 7
step 9, url http://httpbin.org/delay/2, status 200, keys: 7