Failed to update database heartbeat, this node will now exit.

The Heartbeat Updater is a worker thread running on all nodes that performs a simple database query every 5 seconds. The 'heartbeat failure' error message is the application's way of saying that the node received a 'Connection Timed Out' error when connecting to the database.

If the query fails to return in a set amount of time, the Heart Beat Updater worker tells the application that connectivity to the db has been lost and to automatically restarts the node. The application will continue to restart the node until a valid connection to the db is established. This failover procedure is designed to run forever until a connection to the database can be established.

Once the application is able to restart with a clean connection to the database, it then resumes normal operations.