Python urllib2 with keep alive

Question

How can I make a "keep alive" HTTP request using Python's urllib2?

Answer 1

Use the urlgrabber library. This includes an HTTP handler for urllib2 that supports HTTP 1.1 and keepalive:

>>> import urllib2
>>> from urlgrabber.keepalive import HTTPHandler
>>> keepalive_handler = HTTPHandler()
>>> opener = urllib2.build_opener(keepalive_handler)
>>> urllib2.install_opener(opener)
>>> 
>>> fo = urllib2.urlopen('http://www.python.org')

Note: you should use urlgrabber version 3.9.0 or earlier, as the keepalive module has been removed in version 3.9.1

There is a port of the keepalive module to Python 3.

Answer 2

Try urllib3 which has the following features:

• Re-use the same socket connection for multiple requests (HTTPConnectionPool and HTTPSConnectionPool) (with optional client-side certificate verification).
• File posting (encode_multipart_formdata).
• Built-in redirection and retries (optional).
• Supports gzip and deflate decoding.
• Thread-safe and sanity-safe.
• Small and easy to understand codebase perfect for extending and building upon. For a more comprehensive solution, have a look at Requests.

or a much more comprehensive solution - Requests - which supports keep-alive from version 0.8.0 (by using urllib3 internally) and has the following features:

• Extremely simple HEAD, GET, POST, PUT, PATCH, DELETE Requests.
• Gevent support for Asyncronous Requests.
• Sessions with cookie persistience.
• Basic, Digest, and Custom Authentication support.
• Automatic form-encoding of dictionaries
• A simple dictionary interface for request/response cookies.
• Multipart file uploads.
• Automatc decoding of Unicode, gzip, and deflate responses.
• Full support for unicode URLs and domain names.

Answer 3

Or check out httplib's HTTPConnection.

Answer 4

Unfortunately keepalive.py was removed from urlgrabber on 25 Sep 2009 by the following change after urlgrabber was changed to depend on pycurl (which supports keep-alive):

http://yum.baseurl.org/gitweb?p=urlgrabber.git;a=commit;h=f964aa8bdc52b29a2c137a917c72eecd4c4dda94

However, you can still get the last revision of keepalive.py here:

http://yum.baseurl.org/gitweb?p=urlgrabber.git;a=blob_plain;f=urlgrabber/keepalive.py;hb=a531cb19eb162ad7e0b62039d19259341f37f3a6

Answer 5

Note that urlgrabber does not entirely work with python 2.6. I fixed the issues (I think) by making the following modifications in keepalive.py.

In keepalive.HTTPHandler.do_open() remove this

     if r.status == 200 or not HANDLE_ERRORS:
         return r

And insert this

     if r.status == 200 or not HANDLE_ERRORS:
         # [speedplane] Must return an adinfourl object
         resp = urllib2.addinfourl(r, r.msg, req.get_full_url())
         resp.code = r.status
         resp.msg = r.reason
         return resp

Answer 6

Please avoid collective pain and use Requests instead. It will do the right thing by default and use keep-alive if applicable.

Answer 7

Here's a somewhat similar urlopen() that does keep-alive, though it's not threadsafe.

try:
    from http.client import HTTPConnection, HTTPSConnection
except ImportError:
    from httplib import HTTPConnection, HTTPSConnection
import select
connections = {}


def request(method, url, body=None, headers={}, **kwargs):
    scheme, _, host, path = url.split('/', 3)
    h = connections.get((scheme, host))
    if h and select.select([h.sock], [], [], 0)[0]:
        h.close()
        h = None
    if not h:
        Connection = HTTPConnection if scheme == 'http:' else HTTPSConnection
        h = connections[(scheme, host)] = Connection(host, **kwargs)
    h.request(method, '/' + path, body, headers)
    return h.getresponse()


def urlopen(url, data=None, *args, **kwargs):
    resp = request('POST' if data else 'GET', url, data, *args, **kwargs)
    assert resp.status < 400, (resp.status, resp.reason, resp.read())
    return resp