code: def get(self):
      
      try:
        cluster = self.get_argument_cluster()
        role = self.get_argument_role()
        environ = self.get_argument_environ()
        topology_name = self.get_argument_topology()
        instance = self.get_argument_instance()
        topology_info = self.tracker.getTopologyInfo(topology_name, cluster, role, environ)
        result = yield getInstancePid(topology_info, instance)
        self.write_success_response(result)
      except Exception as e:
        Log.debug(traceback.format_exc())
        self.write_error_response(e)
docs: get method