parameters: (self,
                 session,
                 devices=None,
                 ping_interval=60,
                 shutdown_timeout=2 * 3600)
docstring: Initialize a watchdog manager.
  
      Args:
        session: Session connected to worker devices.  A cloned session and graph
          will be created for managing worker pings.
        devices: Set of devices to monitor.  If none, all workers will be
          monitored.
        ping_interval: Time, in seconds, between watchdog pings.
        shutdown_timeout: Time, in seconds, before watchdog timeout.
docstring_summary: Initialize a watchdog manager.
docstring_tokens: Initialize a watchdog manager .
function: def __init__(self,
                 session,
                 devices=None,
                 ping_interval=60,
                 shutdown_timeout=2 * 3600):
      """Initialize a watchdog manager.
  
      Args:
        session: Session connected to worker devices.  A cloned session and graph
          will be created for managing worker pings.
        devices: Set of devices to monitor.  If none, all workers will be
          monitored.
        ping_interval: Time, in seconds, between watchdog pings.
        shutdown_timeout: Time, in seconds, before watchdog timeout.
      """
      threading.Thread.__init__(self)
      self.ping_interval = ping_interval
      self.shutdown_timeout = shutdown_timeout
      self.daemon = True
      self._config = session._config  # pylint: disable=protected-access
      self._target = session.sess_str
      self._running = False
      self._devices = devices
  
      self._graph = None
      self._session = None
      self._worker_manager = None
function_tokens: def __init__ ( self , session , devices = None , ping_interval = 60 , shutdown_timeout = 2 * 3600 ) : threading . Thread . __init__ ( self ) self . ping_interval = ping_interval self . shutdown_timeout = shutdown_timeout self . daemon = True self . _config = session . _config # pylint: disable=protected-access self . _target = session . sess_str self . _running = False self . _devices = devices self . _graph = None self . _session = None self . _worker_manager = None