parallel.py

#!/usr/bin/env python3

# Small snippet of code to demonstrate fetching remote resources in parallel

import asyncio
import aiohttp
import random
import time

async def req(session, delay):
    url = f'http://httpbin.org/delay/{delay}'
    async with session.get(url) as resp:
        result = (resp.status, await resp.text())
    return result

async def main():
    conn = aiohttp.TCPConnector(limit=20)
    async with aiohttp.ClientSession(connector=conn) as sess:
        tasks = []
        for i in range(40):
            delay = random.uniform(.5, 5.5)
            tasks.append(req(sess, delay))

        await asyncio.gather(*tasks)


start = time.time()
asyncio.run(main())
print(f'duration: {time.time() - start}')

# Sample output:
# $ python parallel.py
# duration: 10.057737827301025