(下一个项目的自我提示)

Python 3解决方案只使用请求。它是最简单且快速的，不需要多处理或复杂的异步库。

最重要的方面是重用连接，特别是对于HTTPS (TLS需要额外的往返才能打开)。注意，连接是特定于子域的。如果在多个域上抓取多个页面，则可以对url列表进行排序，以最大化连接重用(它有效地按域进行排序)。

当给定足够的线程时，它将与任何异步代码一样快。(请求在等待响应时释放python GIL)。

[带有日志记录和错误处理的生产等级代码]

import logging
import requests
import time
from concurrent.futures import ThreadPoolExecutor, as_completed

# source: https://stackoverflow.com/a/68583332/5994461

THREAD_POOL = 16

# This is how to create a reusable connection pool with python requests.
session = requests.Session()
session.mount(
    'https://',
    requests.adapters.HTTPAdapter(pool_maxsize=THREAD_POOL,
                                  max_retries=3,
                                  pool_block=True)
)

def get(url):
    response = session.get(url)
    logging.info("request was completed in %s seconds [%s]", response.elapsed.total_seconds(), response.url)
    if response.status_code != 200:
        logging.error("request failed, error code %s [%s]", response.status_code, response.url)
    if 500 <= response.status_code < 600:
        # server is overloaded? give it a break
        time.sleep(5)
    return response

def download(urls):
    with ThreadPoolExecutor(max_workers=THREAD_POOL) as executor:
        # wrap in a list() to wait for all requests to complete
        for response in list(executor.map(get, urls)):
            if response.status_code == 200:
                print(response.content)

def main():
    logging.basicConfig(
        format='%(asctime)s.%(msecs)03d %(levelname)-8s %(message)s',
        level=logging.INFO,
        datefmt='%Y-%m-%d %H:%M:%S'
    )

    urls = [
        "https://httpstat.us/200",
        "https://httpstat.us/200",
        "https://httpstat.us/200",
        "https://httpstat.us/404",
        "https://httpstat.us/503"
    ]

    download(urls)

if __name__ == "__main__":
    main()

自从2010年这篇文章发布以来，事情发生了很大的变化，我还没有尝试过所有其他的答案，但我尝试了一些，我发现使用python3.6对我来说这是最好的。

在AWS上运行时，我每秒可以获取大约150个独特的域名。

import concurrent.futures
import requests
import time

out = []
CONNECTIONS = 100
TIMEOUT = 5

tlds = open('../data/sample_1k.txt').read().splitlines()
urls = ['http://{}'.format(x) for x in tlds[1:]]

def load_url(url, timeout):
    ans = requests.head(url, timeout=timeout)
    return ans.status_code

with concurrent.futures.ThreadPoolExecutor(max_workers=CONNECTIONS) as executor:
    future_to_url = (executor.submit(load_url, url, TIMEOUT) for url in urls)
    time1 = time.time()
    for future in concurrent.futures.as_completed(future_to_url):
        try:
            data = future.result()
        except Exception as exc:
            data = str(type(exc))
        finally:
            out.append(data)

            print(str(len(out)),end="\r")

    time2 = time.time()

print(f'Took {time2-time1:.2f} s')

使用grequests，它是requests + Gevent模块的组合。

GRequests允许您使用带有Gevent的Requests来轻松地生成异步HTTP请求。

用法很简单:

import grequests

urls = [
   'http://www.heroku.com',
   'http://tablib.org',
   'http://httpbin.org',
   'http://python-requests.org',
   'http://kennethreitz.com'
]

创建一组未发送的请求:

>>> rs = (grequests.get(u) for u in urls)

同时发送:

>>> grequests.map(rs)
[<Response [200]>, <Response [200]>, <Response [200]>, <Response [200]>, <Response [200]>]

一个解决方案:

from twisted.internet import reactor, threads
from urlparse import urlparse
import httplib
import itertools


concurrent = 200
finished=itertools.count(1)
reactor.suggestThreadPoolSize(concurrent)

def getStatus(ourl):
    url = urlparse(ourl)
    conn = httplib.HTTPConnection(url.netloc)   
    conn.request("HEAD", url.path)
    res = conn.getresponse()
    return res.status

def processResponse(response,url):
    print response, url
    processedOne()

def processError(error,url):
    print "error", url#, error
    processedOne()

def processedOne():
    if finished.next()==added:
        reactor.stop()

def addTask(url):
    req = threads.deferToThread(getStatus, url)
    req.addCallback(processResponse, url)
    req.addErrback(processError, url)   

added=0
for url in open('urllist.txt'):
    added+=1
    addTask(url.strip())

try:
    reactor.run()
except KeyboardInterrupt:
    reactor.stop()

Testtime:

[kalmi@ubi1:~] wc -l urllist.txt
10000 urllist.txt
[kalmi@ubi1:~] time python f.py > /dev/null 

real    1m10.682s
user    0m16.020s
sys 0m10.330s
[kalmi@ubi1:~] head -n 6 urllist.txt
http://www.google.com
http://www.bix.hu
http://www.godaddy.com
http://www.google.com
http://www.bix.hu
http://www.godaddy.com
[kalmi@ubi1:~] python f.py | head -n 6
200 http://www.bix.hu
200 http://www.bix.hu
200 http://www.bix.hu
200 http://www.bix.hu
200 http://www.bix.hu
200 http://www.bix.hu

Pingtime:

bix.hu is ~10 ms away from me
godaddy.com: ~170 ms
google.com: ~30 ms

pip install requests-threads

使用实例使用async/await - send 100个并发请求

from requests_threads import AsyncSession

session = AsyncSession(n=100)

async def _main():
    rs = []
    for _ in range(100):
        rs.append(await session.get('http://httpbin.org/get'))
    print(rs)

if __name__ == '__main__':
    session.run(_main)

此示例仅适用于Python 3。您还可以提供自己的asyncio事件循环!

使用实例Twisted

from twisted.internet.defer import inlineCallbacks
from twisted.internet.task import react
from requests_threads import AsyncSession

session = AsyncSession(n=100)

@inlineCallbacks
def main(reactor):
    responses = []
    for i in range(100):
        responses.append(session.get('http://httpbin.org/get'))

    for response in responses:
        r = yield response
        print(r)

if __name__ == '__main__':
    react(main)

这个例子在Python 2和Python 3上都可以运行。

也许这对我的回购有帮助，一个基本的例子， 用python编写快速异步HTTP请求

线程绝对不是这里的答案。它们将提供进程和内核瓶颈，以及吞吐量限制，如果总体目标是“最快的方式”，这些限制是不可接受的。

稍微扭曲一点，它的异步HTTP客户端会给你更好的结果。