code: def shutdown_plasma(self):
      for host in self.hosts:
          if host != get_node_ip():
              p = subprocess.Popen(
                  ["ssh", "root@{}".format(host), "pkill plasma"]
              )
          else:
              p = subprocess.Popen(["pkill", "plasma"])
          os.waitpid(p.pid, 0)
  
file_path: BigDL/python/orca/src/bigdl/orca/learn/mpi/mpi_runner.py
imports: import os
  import sys
  import subprocess
  import getpass
  from bigdl.dllib.utils.utils import get_node_ip
  from bigdl.dllib.utils.log4Error import *
label_desc: Use image node_id 5 for calling the MPIRunner obj's underlying member method code with example usage: obj.shutdown_plasma() without return types