Resolution:
If the GridServer Manager is not working correctly, it may appear that there are two or more instances of the Manager running, because there are many duplicate messages.

This occurs when there is an additional directory in the webapps directory of your GridServer installation. Typically, the webapps directory includes a single livecluster directory. However, other directories may have been created, possibly due to the installer copying them during an upgrade. The Resin application server will automatically creates a web application for any directory in the webapps directory, thereby trying to start multiple copies of the GridServer Manager.

To remedy this situation, remove any extra directories within the webapp directory. On an upgrade, do not copy the old directory into the webapps directory.