Python3.x 如何使用 asyncio 添加连接超时

我想很快连接到许多不同网站的列表.

我该如何实现这一点？

import ssl
import asyncio
from contextlib import suppress
from concurrent.futures import ThreadPoolExecutor
import time


@asyncio.coroutine
def run():
    while True:
        host = yield from q.get()
        if not host:
            break

        with suppress(ssl.CertificateError):
            reader, writer = yield from asyncio.open_connection(host[1], 443, ssl=True) #timout option?
            reader.close()
            writer.close()


@asyncio.coroutine
def load_q():
    # only 3 entries for debugging reasons
    for host in [[1, 'python.org'], [2, 'qq.com'], [3, 'google.com']]:
        yield from q.put(host)
    for _ in range(NUM):
        q.put(None)


if __name__ == "__main__":
    NUM = 1000
    q = asyncio.Queue()

    loop = asyncio.get_event_loop()
    loop.set_default_executor(ThreadPoolExecutor(NUM))

    start = time.time()
    coros = [asyncio.async(run()) for i in range(NUM)]
    loop.run_until_complete(load_q())
    loop.run_until_complete(asyncio.wait(coros))
    end = time.time()
    print(end-start)

(旁注:有人知道如何优化这个吗？)