# loop.run_in_executor, запуск в отдельном потоке
import asyncio
from urllib.request import urlopen

# a synchronous function
def sync_get_url(url):
    return urlopen(url).read()

async def load_url(url, loop=None):
    future = loop.run_in_executor(None, sync_get_url, url)
    response = await future
    print(len(response))
    
loop = asyncio.get_event_loop()
loop.run_until_complete(load_url("http://sinfo/", loop=loop))