Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Performance Tuning Guide

Enabling the Health Checker

The load balancer periodically checks all the configured Application Server instances that are marked as unhealthy, based on the values specified in the health-checker element in the loadbalancer.xml file. Enabling the health checker is optional. If the health checker is not enabled, periodic health check of unhealthy instances is not performed.

The load balancer’s health check mechanism communicates with the application server instance using HTTP. The health checker sends an HTTP request to the URL specified and waits for a response. The status code in the HTTP response header should be between 100 and 500 to consider the instance to be healthy.

To enable the health checker, edit the following properties:

If the typical response from the server takes n seconds and under peak load takes m seconds, then set the timeout-in-seconds property to m + n, as follows:


For more information, see Configuring the Load Balancer in Sun Java System Application Server Enterprise Edition 8.1 2005Q2 High Availability Administration Guide.