gistfile1.txt

#!/usr/bin/env python3
import asyncio


class HTTPManager():

  def __init__(self):
    self.cache = {}
  

  async def get_throttled_url(self, url, throttle=2):
    if url not in self.cache:
      self.cache[url] = asyncio.Semaphore(throttle)
    async with self.cache[url]:
      await self.get_url(url)
    return 3


  async def get_url(self, url):
    print('GET {url} ...'.format(url=url))
    await asyncio.sleep(2)
    print('GOT IT: {url}.'.format(url=url))
    return 2


# Python 3.7+
loop = asyncio.get_event_loop()
http = HTTPManager()
urls = ("abc", "xyz", "abc", "eee", "abc", "eee", "xyz", "xyz", "abc", "abc", "xyz", "eee")
todo = [http.get_throttled_url(url) for url in urls]
w = asyncio.wait(todo)
res, _ = loop.run_until_complete(w)
for r in res:
  print(r)
loop.close()