参考链接：http://docs.python.org/2/howto/urllib2.html？highlight=urlopen％20timeout

The Python support for fetching resources the web is layered. urllib2 uses the httplib library， which in turn uses the socket library.

As of Python 2.3 you can specify how long a socket should wait for a response before timing out. This can be useful in applications which have to fetch web pages. By default the socket module has no timeout and can hang. Currently， the socket timeout is not exposed at the httplib or urllib2 levels. However， you can set the default timeout globally for all sockets using

import socket

import urllib2



＃ timeout in seconds

timeout = 10

socket.setdefaulttimeout（timeout）



＃ this call to urllib2.urlopen now uses the default timeout

＃ we have set in the socket module

req = urllib2.Request（http://www.voidspace.org.uk）

response = urllib2.urlopen（req）