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
我发现使用tornado包是最快和最简单的方法来实现这一点:
from tornado import ioloop, httpclient, gen
def main(urls):
"""
Asynchronously download the HTML contents of a list of URLs.
:param urls: A list of URLs to download.
:return: List of response objects, one for each URL.
"""
@gen.coroutine
def fetch_and_handle():
httpclient.AsyncHTTPClient.configure(None, defaults=dict(user_agent='MyUserAgent'))
http_client = httpclient.AsyncHTTPClient()
waiter = gen.WaitIterator(*[http_client.fetch(url, raise_error=False, method='HEAD')
for url in urls])
results = []
# Wait for the jobs to complete
while not waiter.done():
try:
response = yield waiter.next()
except httpclient.HTTPError as e:
print(f'Non-200 HTTP response returned: {e}')
continue
except Exception as e:
print(f'An unexpected error occurred querying: {e}')
continue
else:
print(f'URL \'{response.request.url}\' has status code <{response.code}>')
results.append(response)
return results
loop = ioloop.IOLoop.current()
web_pages = loop.run_sync(fetch_and_handle)
return web_pages
my_urls = ['url1.com', 'url2.com', 'url100000.com']
responses = main(my_urls)
print(responses[0])
其他回答
Twistedless解决方案:
from urlparse import urlparse
from threading import Thread
import httplib, sys
from Queue import Queue
concurrent = 200
def doWork():
while True:
url = q.get()
status, url = getStatus(url)
doSomethingWithResult(status, url)
q.task_done()
def getStatus(ourl):
try:
url = urlparse(ourl)
conn = httplib.HTTPConnection(url.netloc)
conn.request("HEAD", url.path)
res = conn.getresponse()
return res.status, ourl
except:
return "error", ourl
def doSomethingWithResult(status, url):
print status, url
q = Queue(concurrent * 2)
for i in range(concurrent):
t = Thread(target=doWork)
t.daemon = True
t.start()
try:
for url in open('urllist.txt'):
q.put(url.strip())
q.join()
except KeyboardInterrupt:
sys.exit(1)
这个方案比twisted方案稍微快一点,并且使用更少的CPU。
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。
我发现使用tornado包是最快和最简单的方法来实现这一点:
from tornado import ioloop, httpclient, gen
def main(urls):
"""
Asynchronously download the HTML contents of a list of URLs.
:param urls: A list of URLs to download.
:return: List of response objects, one for each URL.
"""
@gen.coroutine
def fetch_and_handle():
httpclient.AsyncHTTPClient.configure(None, defaults=dict(user_agent='MyUserAgent'))
http_client = httpclient.AsyncHTTPClient()
waiter = gen.WaitIterator(*[http_client.fetch(url, raise_error=False, method='HEAD')
for url in urls])
results = []
# Wait for the jobs to complete
while not waiter.done():
try:
response = yield waiter.next()
except httpclient.HTTPError as e:
print(f'Non-200 HTTP response returned: {e}')
continue
except Exception as e:
print(f'An unexpected error occurred querying: {e}')
continue
else:
print(f'URL \'{response.request.url}\' has status code <{response.code}>')
results.append(response)
return results
loop = ioloop.IOLoop.current()
web_pages = loop.run_sync(fetch_and_handle)
return web_pages
my_urls = ['url1.com', 'url2.com', 'url100000.com']
responses = main(my_urls)
print(responses[0])
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
最简单的方法是使用Python的内置线程库。它们不是“真正的”/内核线程。它们有问题(比如序列化),但足够好了。你需要一个队列和线程池。这里有一个选项,但是编写自己的选项很简单。您无法并行处理所有100,000个调用,但可以同时发出100个(或左右)调用。
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