public static synchronized void shutdown(){
  _shutdown=true;
  Watchdog watchdog=_watchdog;
  if (watchdog != null)   watchdog.interrupt();
}

public static synchronized void shutdown ( ) { _shutdown = true ; Watchdog watchdog = _watchdog ; if ( watchdog != null ) watchdog . interrupt ( ) ; }
shuts down the watchdog if operation , this is irreversable process .
