Parallel (async) HTTP requests with configurable concurrency using Python/aiohttp/asyncio

concurrency.py

import aiohttp
import nest_asyncio
nest_asyncio.apply()
from random import randint

class HttpClient:
  def __init__(self, session, concurrency):
    self.__session = session
    self.concurrency = asyncio.Semaphore(concurrency)

  async def download(self, url):
    print(datetime.now(), url, 'downloading')
    async with self.__session.get(url) as response:
      print(datetime.now(), url, response.status, 'downloaded')
      return response.status

  async def safe_download(self, url):
    async with self.concurrency:
      return await self.download(url)

async def main(urls):
  async with aiohttp.ClientSession() as session:
    http_client = HttpClient(session=session, concurrency=4)
    tasks = [asyncio.ensure_future(http_client.safe_download(url)) for url in urls]
    await asyncio.gather(*tasks)

urls = []
for i in range(10):
  rand = randint(2000, 5000)
  url = "https://deelay.me/{}/http://httpbin.org/get".format(rand)
  urls.append(url)
print(urls)

loop = asyncio.get_event_loop()
try:
  loop.run_until_complete(main(urls))
finally:
  loop.run_until_complete(loop.shutdown_asyncgens())
  loop.close()