Sun GlassFish Enterprise Server 2.1 Performance Tuning Guide

Choosing the Garbage Collection Algorithm

Pauses during a full GC of more than four seconds can cause intermittent failures in persisting session data into HADB.

While GC is going on, the Application Server isn’t running. If the pause is long enough, the HADB times out the existing connections. Then, when the application server resumes its activities, the HADB generates errors when the application server attempts to use those connections to persist session data. It generates errors like, “Failed to store session data,” “Transaction Aborted,” or “Failed to connect to HADB server.”

To prevent that problem, use the CMS collector as the GC algorithm. This collector can cause a drop in throughput for heavily utilized systems, because it is running more or less constantly. But it prevents the long pauses that can occur when the garbage collector runs infrequently.

ProcedureTo use the CMS collector

  1. Make sure that the system is not using 100 percent of its CPU.

  2. Configure HADB timeouts, as described in the Administration Guide.

  3. Configure the CMS collector in the server instance.

    To do this, add the following JVM options:

    • -XX:+UseConcMarkSweepGC

    • -XX:SoftRefLRUPolicyMSPerMB=1