socket ResourceWarning using urllib in Python 3

I don't know if this is the answer, but it is part of the way to an answer.

If I add the header "connection: close" to the response from my web services, the HTTPResponse object seems to clean itself up properly without a warning.

And in fact, the HTTP Spec (http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html) says:

HTTP/1.1 applications that do not support persistent connections MUST include the "close" connection option in every message.

So the problem was on the server end (i.e. my fault!). In the event that you don't have control over the headers coming from the server, I don't know what you can do.

I had the same problem with urllib3 and I just added a context manager to close connection automatically:

import urllib3

def get(addr, headers):
    """ this function will close the connection after a http request. """
    with urllib3.PoolManager() as conn:
        res = conn.request('GET', addr, headers=headers)
        if r.status == 200:
            return res.data
        else:
            raise ConnectionError(res.reason)

Note that urllib3 is designed to have a pool of connections and to keep connections alive for you. This can significantly speed up your application, if it needs to make a series of requests, e.g. few calls to the backend API.

Please read urllib3 documentation re connection pools here: https://urllib3.readthedocs.io/en/1.5/pools.html

P.S. you could also use requests lib, which is not a part of the Python standard lib (at 2019) but is very powerful and simple to use: http://docs.python-requests.org/en/master/