class_docstr: Base class for the job.
  
  After establishing connection with the remote object, the job will
  create a remote class instance locally and enter an infinite loop
  in a separate process, waiting for commands from the remote object.
class_docstr_tok: ["Base","class","for","the","job",".","After","establishing","connection","with","the","remote","object",",","the","job","will","create","a","remote","class","instance","locally","and","enter","an","infinite","loop","in","a","separate","process",",","waiting","for","commands","from","the","remote","object","."]
docstr: Create a socket server that reply the ping signal from client.
  This signal is used to make sure that the job is still alive.
docstr_tok: ["Create","a","socket","server","that","reply","the","ping","signal","from","client",".","This","signal","is","used","to","make","sure","that","the","job","is","still","alive","."]
code: def _reply_ping(self, socket):
      """Create a socket server that reply the ping signal from client.
      This signal is used to make sure that the job is still alive.
      """
      message = socket.recv_multipart()
      client_heartbeat_server_addr = to_str(message[1])
      max_memory = to_str(message[2])
      if max_memory != "None":
          self.max_memory = float(max_memory)
      self.gpu = to_str(message[3])
      self.instance_id = to_str(message[4])
      socket.send_multipart([remote_constants.HEARTBEAT_TAG])
  
      def client_heartbeat_exit_callback_func():
          with self.lock:
              self.remove_job_socket.send_multipart(
                  [
                      remote_constants.KILLJOB_TAG,
                      to_byte(self.job_address),
                  ]
              )
              try:
                  _ = self.remove_job_socket.recv_multipart()
              except zmq.error.Again as e:
                  pass
          logger.warning(
              "[Job] lost connection with the client. This job will exit."
          )
          os._exit(1)
  
      # a thread that sends heartbeat signals from the client
      self.client_heartbeat_client_thread = HeartbeatClientThread(
          client_id=self.instance_id,
          heartbeat_server_addr=client_heartbeat_server_addr,
          heartbeat_exit_callback_func=client_heartbeat_exit_callback_func,
      )
      self.client_heartbeat_client_thread.setDaemon(True)
      self.client_heartbeat_client_thread.start()
  
      memory_monitor_thread = threading.Thread(
          target=self._check_used_memory
      )
      memory_monitor_thread.setDaemon(True)
      memory_monitor_thread.start()
  
      socket.close(0)
  
imports: import os
  import compatible_trick
  import argparse
  import cloudpickle
  import pickle
  import psutil
  import re
  import sys
  import tempfile
  import shutil
  import threading
  import time
  import traceback
  import zmq
  import importlib
  import parl
  from multiprocessing import Process, Pipe
  from parl.utils import to_str, to_byte, get_ip_address, logger
  from parl.remote.communication import loads_argument, loads_return, dumps_argument, dumps_return
  from parl.remote import remote_constants
  from parl.utils.exceptions import SerializeError, DeserializeError
  from parl.remote.message import InitializedJob
  from parl.remote.utils import redirect_output_to_file
  from parl.remote.remote_class_serialization import load_remote_class
  from parl.remote.zmq_utils import create_server_socket, create_client_socket
  from parl.remote.grpc_heartbeat import HeartbeatServerThread, HeartbeatClientThread
label_desc: Use image node_id 4 for calling the Job obj's underlying member method code with example usage: obj._reply_ping(socket) without return types