How to use the eventlet.hubs.use_hub function in eventlet

def _child_process(self, service):
        self._child_process_handle_signal()

        # Reopen the eventlet hub to make sure we don't share an epoll
        # fd with parent and/or siblings, which would be bad
        eventlet.hubs.use_hub()

        # Close write to ensure only parent has it open
        os.close(self.writepipe)
        # Create greenthread to watch for parent to close pipe
        eventlet.spawn_n(self._pipe_watcher)

        # Reseed random number generator
        random.seed()

        launcher = Launcher()
        launcher.launch_service(service)
        return launcher

def _child_process(self, service):
        self._child_process_handle_signal()

        # Reopen the eventlet hub to make sure we don't share an epoll
        # fd with parent and/or siblings, which would be bad
        eventlet.hubs.use_hub()

        # Close write to ensure only parent has it open
        os.close(self.writepipe)
        # Create greenthread to watch for parent to close pipe
        eventlet.spawn_n(self._pipe_watcher)

        # Reseed random number generator
        random.seed()

        launcher = Launcher()
        launcher.launch_service(service)
        return launcher

def _child_process(self, service):
        self._child_process_handle_signal()

        # Reopen the eventlet hub to make sure we don't share an epoll
        # fd with parent and/or siblings, which would be bad
        eventlet.hubs.use_hub()

        # Close write to ensure only parent has it open
        os.close(self.writepipe)
        # Create greenthread to watch for parent to close pipe
        eventlet.spawn_n(self._pipe_watcher)

        # Reseed random number generator
        random.seed()

        launcher = Launcher()
        launcher.launch_service(service)
        return launcher

def new_websocket_client(self):
        """Called after a new WebSocket connection has been established."""
        # Reopen the eventlet hub to make sure we don't share an epoll
        # fd with parent and/or siblings, which would be bad
        from eventlet import hubs
        hubs.use_hub()

        # The zun expected behavior is to have token
        # passed to the method GET of the request
        parse = urlparse.urlparse(self.path)
        if parse.scheme not in ('http', 'https'):
            # From a bug in urlparse in Python < 2.7.4 we cannot support
            # special schemes (cf: https://bugs.python.org/issue9374)
            if sys.version_info < (2, 7, 4):
                raise exception.ZunException(
                    _("We do not support scheme '%s' under Python < 2.7.4, "
                      "please use http or https") % parse.scheme)

        query = parse.query
        token = urlparse.parse_qs(query).get("token", [""]).pop()
        uuid = urlparse.parse_qs(query).get("uuid", [""]).pop()
        exec_id = urlparse.parse_qs(query).get("exec_id", [""]).pop()

def run_server(self):
        """Run a WSGI server."""
        eventlet.wsgi.HttpProtocol.default_request_version = "HTTP/1.0"
        eventlet.hubs.use_hub('poll')
        eventlet.patcher.monkey_patch(all=False, socket=True)
        self.pool = eventlet.GreenPool(size=self.threads)
        try:
            eventlet.wsgi.server(self.sock, self.application,
                    log=WritableLogger(self.logger), custom_pool=self.pool)
        except socket.error, err:
            if err[0] != errno.EINVAL:
                raise
        self.pool.waitall()

def patch(self):
        hubs.use_hub()
        eventlet.monkey_patch(os=False)
        patch_sendfile()

def patch(self):
        hubs.use_hub()
        eventlet.monkey_patch(os=False)
        patch_sendfile()

def _child_process(self, service):
        self._child_process_handle_signal()

        # Reopen the eventlet hub to make sure we don't share an epoll
        # fd with parent and/or siblings, which would be bad
        eventlet.hubs.use_hub()

        # Close write to ensure only parent has it open
        os.close(self.writepipe)
        # Create greenthread to watch for parent to close pipe
        eventlet.spawn_n(self._pipe_watcher)

        # Reseed random number generator
        random.seed()

        launcher = Launcher()
        launcher.launch_service(service)
        return launcher

def new_websocket_client(self):
                    if Config.is_eventlet():
                        from eventlet import hubs
                        hubs.use_hub()

                    return ProxyRequestHandler.new_websocket_client(self)
        except: