Some pcsd processes are not terminated with SIGTERM

Issue

• systemctl stop pcsd takes 90 seconds, and the following messages are shown.

  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: State 'stop-sigterm' timed out. Killing.
  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: Killing process 4423 (pcsd) with signal SIGKILL.
  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: Killing process 4426 (pcsd) with signal SIGKILL.
  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: Killing process 4440 (pcsd) with signal SIGKILL.
  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: Killing process 4427 (pcsd) with signal SIGKILL.
  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: Killing process 4435 (pcsd) with signal SIGKILL.
  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: Killing process 4468 (pcsd) with signal SIGKILL.
  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: Killing process 4484 (pcsd) with signal SIGKILL.
  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: Killing process 4486 (pcsd) with signal SIGKILL.
  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: Main process exited, code=killed, status=9/KILL
  Feb 27 11:58:24 node1 systemd[1]: pcsd.service: Failed with result 'timeout'.
  

• When stopping pcsd.service, some pcsd processes are not terminated as follows.

  # ps -ef
  UID          PID    PPID  C STIME TTY          TIME CMD
  [...]
  root        1848       1  0 14:43 ?        00:00:50 /usr/bin/python3 -Es /usr/sbin/pcsd
  root        2565    1848  0 14:43 ?        00:00:15 /usr/bin/python3 -Es /usr/sbin/pcsd
  root        2578    1848  0 14:43 ?        00:00:00 /usr/bin/python3 -Es /usr/sbin/pcsd
  root        2580    1848  0 14:43 ?        00:00:00 [pcsd] <defunct>
  root        2581    1848  0 14:43 ?        00:00:00 [pcsd] <defunct>
  root        2583    1848  0 14:43 ?        00:00:00 [pcsd] <defunct>
  root        2584    1848  0 14:43 ?        00:00:00 [pcsd] <defunct>
  root        2585    1848  0 14:43 ?        00:00:00 [pcsd] <defunct>
  root        2588    1848  0 14:43 ?        00:00:00 [pcsd] <defunct>
  root        2590    1848  0 14:43 ?        00:00:00 [pcsd] <defunct>
  [...]
  root        9652    4487  0 17:24 pts/0    00:00:00 systemctl stop pcsd