aio.py

#!/bin/env python

# https://towardsdatascience.com/stop-waiting-start-using-async-and-await-18fcd1c28fd0
# docker run -it -v $PWD:/src -w /src python:3.7-slim
# pip install aiohttp asyncio requests

import aiohttp
import asyncio
import time
from typing import Any, Iterable, List, Tuple, Callable
import os
import requests

def image_name_from_url(url: str) -> str:
    return url.split("/")[-1]

def download_all(urls: Iterable[str]) -> List[Tuple[str, bytes]]:
    def download(url: str) -> Tuple[str, bytes]:
        print(f"Start downloading {url}")
        with requests.Session() as s:
            resp = s.get(url)
            out= image_name_from_url(url), resp.content
        print(f"Done downloading {url}")
        return out
    return [download(url) for url in urls]

async def donwload_aio(urls:Iterable[str])->List[Tuple[str, bytes]]:
    async def download(url: str) -> Tuple[str, bytes]:
        print(f"Start downloading {url}")
        async with aiohttp.ClientSession() as s:
            resp = await s.get(url)
            out = image_name_from_url(url), await resp.read()
        print(f"Done downloading {url}")
        return out
        
    return await asyncio.gather(*[download(url) for url in urls])
    
if __name__ == "__main__":
    # Get list of images from dogs API
    URL = "https://dog.ceo/api/breed/hound/images"
    images = requests.get(URL).json()["message"]
# Take only 200 images to not run into issues with gather     
    reduced = images[:200]
    st = time.time()
    images_s = download_all(reduced)
    print(f"Synchronous exec took {time.time() - st} seconds")
    
    st = time.time()
    images_a = asyncio.run(donwload_aio(reduced))
    print(f"Asynchronous exec took {time.time() - st} seconds")