aiohttp stream download

down.py

from contextlib import closing

import asyncio
import aiohttp


f = open('path/to/file', 'wb')
url = 'http://speedtest.wdc01.softlayer.com/downloads/test100.zip'
chunk_size = 5 * 2**20  # MB


async def download_file(session, url, f):
    async with session.get(url) as response:
        data_to_read = True
        while data_to_read:
            data = bytearray()
            red = 0
            while red < chunk_size:
                chunk = await response.content.read(chunk_size - red)
                if not chunk:
                    data_to_read = False
                    break
                data.extend(chunk)
                red += len(chunk)
            
            f.write(data)


loop = asyncio.get_event_loop()
with closing(aiohttp.ClientSession(loop=loop)) as session:
    loop.run_until_complete(download_file(session, url, f))

f.close()