asynciotest.py

import sys
import asyncio
from aiohttp import ClientSession

async def fetch(url, session):
    async with session.get(url) as response:
        response = await response.read()

async def limit_fetch(sem, url, session):
    async with sem:
        await fetch(url, session)

async def run(r):
    url = "https://httpbin.org/get/{}"
    tasks = []

    sem = asyncio.Semaphore(1000)

    async with ClientSession() as session:
        for i in range(r):
            task = asyncio.ensure_future(limit_fetch(sem, url.format(i), session))
            tasks.append(task)

        responses = asyncio.gather(*tasks)
        await responses

number = int(sys.argv[1])
loop = asyncio.get_event_loop()

future = asyncio.ensure_future(run(number))
loop.run_until_complete(future)