I am opening a file which has 100,000 URL's. I need to send an HTTP request to each URL and print the status code. I am using Python 2.6, and so far looked at the many confusing ways Python implements threading/concurrency. I have even looked at the python concurrence library, but cannot figure out how to write this program correctly. Has anyone come across a similar problem? I guess generally I need to know how to perform thousands of tasks in Python as fast as possible - I suppose that means 'concurrently'.


当前回答

创建epoll对象, 打开许多客户端TCP套接字, 调整他们的发送缓冲区比请求头多一点, 发送一个请求头-它应该是即时的,只是放置到缓冲区, 在epoll对象中注册套接字 在epoll obect上做。poll, 从.poll中读取每个套接字的前3个字节, 将它们写入sys。Stdout后面跟着\n(不刷新), 关闭客户端套接字。

限制同时打开的套接字数量-在创建套接字时处理错误。只有当另一个套接字关闭时才创建新的套接字。 调整操作系统限制。 尝试分成几个(不是很多)进程:这可能有助于更有效地使用CPU。

其他回答

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。

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

考虑使用风车,虽然风车可能不能做那么多线程。

您可以在5台机器上使用手卷Python脚本,每台机器使用端口40000-60000连接出站,打开100,000个端口连接。

另外,使用一个线程良好的QA应用程序(如OpenSTA)做一个示例测试可能会有所帮助,以了解每个服务器可以处理多少。

另外,试着在LWP::ConnCache类中使用简单的Perl。这样您可能会获得更好的性能(更多的连接)。

这个扭曲的异步web客户端运行得相当快。

#!/usr/bin/python2.7

from twisted.internet import reactor
from twisted.internet.defer import Deferred, DeferredList, DeferredLock
from twisted.internet.defer import inlineCallbacks
from twisted.web.client import Agent, HTTPConnectionPool
from twisted.web.http_headers import Headers
from pprint import pprint
from collections import defaultdict
from urlparse import urlparse
from random import randrange
import fileinput

pool = HTTPConnectionPool(reactor)
pool.maxPersistentPerHost = 16
agent = Agent(reactor, pool)
locks = defaultdict(DeferredLock)
codes = {}

def getLock(url, simultaneous = 1):
    return locks[urlparse(url).netloc, randrange(simultaneous)]

@inlineCallbacks
def getMapping(url):
    # Limit ourselves to 4 simultaneous connections per host
    # Tweak this number, but it should be no larger than pool.maxPersistentPerHost 
    lock = getLock(url,4)
    yield lock.acquire()
    try:
        resp = yield agent.request('HEAD', url)
        codes[url] = resp.code
    except Exception as e:
        codes[url] = str(e)
    finally:
        lock.release()


dl = DeferredList(getMapping(url.strip()) for url in fileinput.input())
dl.addCallback(lambda _: reactor.stop())

reactor.run()
pprint(codes)

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]>]