# modified fetch function with semaphore
import asyncio
from aiohttp import TCPConnector, ClientSession

async def fetch(url, session):
    async with session.get(url) as response:
        delay = response.headers.get("DELAY")
        date = response.headers.get("DATE")
        print("{}:{} with delay {}".format(date, response.url, delay))
        return await response.text()


async def bound_fetch(sem, url, session):
    # Getter function with semaphore.
    async with sem:
        await fetch(url, session)


async def run(r):
    url = "http://localhost:8000/{}"
    tasks = []
    # create instance of Semaphore
    sem = asyncio.Semaphore(1000)

    # Create client session that will ensure we dont open new connection
    # per each request.
    conn = TCPConnector(limit=0)
    async with ClientSession(connector=conn) as session:
        for i in range(r):
            # pass Semaphore and session to every GET request
            task = asyncio.ensure_future(bound_fetch(sem, url.format(i), session))
            tasks.append(task)

        responses = asyncio.gather(*tasks)
        await responses

number = 10000
asyncio.run(run(number))