A example of scrapper using asyncio and aiohttp

scrapper.py

import asyncio
import aiohttp
import bs4
import tqdm


@asyncio.coroutine
def get(*args, **kwargs):
    response = yield from aiohttp.request('GET', *args, **kwargs)
    return (yield from response.read_and_close(decode=True))


@asyncio.coroutine
def wait_with_progress(coros):
    for f in tqdm.tqdm(asyncio.as_completed(coros), total=len(coros)):
        yield from f


def first_magnet(page):
    soup = bs4.BeautifulSoup(page)
    a = soup.find('a', title='Download this torrent using magnet')
    return a['href']


@asyncio.coroutine
def print_magnet(query):
    url = 'http://thepiratebay.se/search/{}/0/7/0'.format(query)
    with (yield from sem):
        page = yield from get(url, compress=True)
    magnet = first_magnet(page)
    print('{}: {}'.format(query, magnet))


distros = ['archlinux', 'ubuntu', 'debian']
sem = asyncio.Semaphore(5)
loop = asyncio.get_event_loop()
f = asyncio.wait([print_magnet(d) for d in distros])
loop.run_until_complete(f)

Perhaps I'm being picky, but you should pass your variable sem to print_magnet() to keep data encapsulation. Was confusing me as I had no idea what this variable was. Apart from that, this was helpful :)

Hi, I did a "POST" version with connection pooling after I'd read the example.

import asyncio
import aiohttp
import ujson
import tqdm

payload = ujson.dumps({'hello': 'world'})
url = "http://127.0.0.1:8000"

sem = asyncio.Semaphore(5)

@asyncio.coroutine
def wait_with_progress(coros):
    for f in tqdm.tqdm(asyncio.as_completed(coros), total=len(coros)):
        yield from f

@asyncio.coroutine
def post():
    resp = yield from aiohttp.request('post', url, data=payload, connector=conn)
    return (yield from resp.text())

@asyncio.coroutine
def print_status(i):
    with (yield from sem):
        status = yield from post()
        #print('#' + str(i) + ' ' + status)

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    conn = aiohttp.connector.TCPConnector()
    f = [print_status(i) for i in range(5000)]
    loop.run_until_complete(wait_with_progress(f))

And the echo server:

from flask import Flask
from flask import request

app = Flask(__name__)

@app.route('/', methods=['POST'])
def echo():
    return request.data

if __name__ == '__main__':
    app.run(port=8000)

The aiohttp method ClientResponse.read_and_close() is gone as of December 2015

Should change line 10 to:

return (yield from response.text())

import asyncio
import aiohttp
import bs4
import tqdm


async def get(*args, **kwargs):
    async with aiohttp.ClientSession() as session:
        async with session.get(*args, **kwargs) as resp:
            return (await resp.text())


def first_magnet(page):
    soup = bs4.BeautifulSoup(page, features="lxml")
    a = soup.find('a', title='Download this torrent using magnet')
    return a['href']


async def print_magnet(query):
    url = 'http://thepiratebay.se/search/{}/0/7/0'.format(query)
    async with sem:
        page = await get(url, compress=True)
    magnet = first_magnet(page)
    print('{}: {}'.format(query, magnet))


distros = ['archlinux', 'ubuntu', 'debian']
sem = asyncio.Semaphore(5)
loop = asyncio.get_event_loop()
f = asyncio.wait([print_magnet(d) for d in distros])
loop.run_until_complete(f)

Tested with Python 3.8, but rip ThePirateBay.

This gist doesn't work with the latest version of Python and asyncio, as of March 2023.

@asyncio.coroutine doesn't exist in asyncio any longer.