python block io 阻塞 eventloop 实例

import asyncio
 
import aiohttp
import requests
 
counter = 0
 
 
class Flag:
    def __init__(self):
        self.flag = False
 
 
big_file_url = "https://reutersinstitute.politics.ox.ac.uk/sites/default/files/2023-06/Digital_News_Report_2023.pdf"
 
 
async def async_req():
    async with aiohttp.ClientSession() as session:
        async with session.get(big_file_url) as response:
            print("!!!!!", response.status)
 
 
def block_req():
    resp = requests.get(big_file_url)
    print("!!!!!!", resp.status_code)
 
 
async def tick(flag: Flag):
    while not flag.flag:
        global counter
        counter += 1
        print("tick", counter)
        await asyncio.sleep(0.1)
 
 
async def main():
    flag = Flag()
    task = asyncio.create_task(tick(flag))
 
    await asyncio.sleep(1)
    block_req()
    # await async_req()
    print("awake")
    await asyncio.sleep(1)
    print("set flag")
    flag.flag = True
    await task
 
 
asyncio.run(main())