import urllib.request 
from multiprocessing.dummy import Pool as ThreadPool

urls = [...]

pool = ThreadPool(len(urls)) 
results = pool.map(urllib.request.urlopen, urls)

pool.close() 
pool.join()

if __name__ ...

import asyncio
import urllib.request

def get_url(codes, url):
    codes.append(urllib.request.urlopen(url).getcode())
    return(codes)
codes = []
urls = [...]
async def get_code(codes, urls):
  for u in urls:
    codes = get_url(codes, u)
  await asyncio.sleep(0)
  for code in codes:
    print(code)

ioloop = asyncio.get_event_loop()
tasks = [ioloop.create_task(get_code(codes, urls))]
wait_tasks = asyncio.wait(tasks)
ioloop.run_until_complete(wait_tasks)
ioloop.close()