crawler/async_crawler.py

import requests
import time
import asyncio
import aiohttp
from bs4 import BeautifulSoup
from urllib.request import urljoin
import re
import multiprocessing as mp

base_url = "https://morvanzhou.github.io/"

if base_url != "http://127.0.0.1:4000/":
    restricted_crawl = True
else:
    restricted_crawl = False

seen = set()
unseen = set([base_url,])


def parse(html):
    soup = BeautifulSoup(html, 'lxml')
    urls = soup.find_all('a', {"href": re.compile('^/.+?/$')})
    title = soup.find('h1').get_text().strip()
    page_urls = set([urljoin(base_url, url['href']) for url in urls])
    url = soup.find('meta', {'property': "og:url"})['content']
    return title, page_urls, url
async def crawl(url,session):
    r =await session.get(url)
    html = await r.text()
    return html

async def main(loop):
    pool = mp.Pool(8)
    async with aiohttp.ClientSession() as session:
        count = 1
        while len(unseen) != 0:
            print('\nAsync Crawling...')
            tasks = [loop.create_task(crawl(url, session)) for url in unseen]
            finished, unfinished = await asyncio.wait(tasks)
            htmls = [f.result() for f in finished]
            
            print('\nDistributed Parsing...')
            parse_jobs = [pool.apply_async(parse, args=(html,)) for html in htmls]
            results = [j.get() for j in parse_jobs]
            
            print('\nAnalysing...')
            seen.update(unseen)
            unseen.clear()
            for title, page_urls, url in results:
                print(count, title, url)
                unseen.update(page_urls - seen)
                count += 1

if __name__ == "__main__":
    t1 = time.time()
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main(loop))
    loop.close()
    print("Async total time: ", time.time() - t1)