Send the request through the server and return the HTTP response.

def _relay(self, **kwargs):
        """Send the request through the server and return the HTTP response."""
        retval = None
        delay_time = 2  # For connection retries
        read_attempts = 0  # For reading from socket
        while retval is None:  # Evict can return False
            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            sock_fp = sock.makefile('rwb')  # Used for pickle
            try:
                sock.connect((self.host, self.port))
                cPickle.dump(kwargs, sock_fp, cPickle.HIGHEST_PROTOCOL)
                sock_fp.flush()
                retval = cPickle.load(sock_fp)
            except:  # pylint: disable=W0702
                exc_type, exc, _ = sys.exc_info()
                socket_error = exc_type is socket.error
                if socket_error and exc.errno == 111:  # Connection refused
                    sys.stderr.write('Cannot connect to multiprocess server. I'
                                     's it running? Retrying in {0} seconds.\n'
                                     .format(delay_time))
                    time.sleep(delay_time)
                    delay_time = min(64, delay_time * 2)
                elif exc_type is EOFError or socket_error and exc.errno == 104:
                    # Failure during socket READ
                    if read_attempts >= 3:
                        raise ClientException('Successive failures reading '
                                              'from the multiprocess server.')
                    sys.stderr.write('Lost connection with multiprocess server'
                                     ' during read. Trying again.\n')
                    read_attempts += 1
                else:
                    raise
            finally:
                sock_fp.close()
                sock.close()
        if isinstance(retval, Exception):
            raise retval  # pylint: disable=E0702
        return retval