Sun Java System Web Server 7.0 Update 4 Performance Tuning, Sizing, and Scaling Guide

Java Virtual Machine (JVM) Information

JVM statistics are displayed through the Admin Console, the CLI, and stats-xml only. They are not shown in perfdump.

The following table shows an example of the JVM statistics displayed in the Admin Console:

Table 2–7 Java Virtual Machine (JVM) Statistics

Virtual Machine Name 

Java HotSpotTM Server VM

Virtual Machine Vendor 

Sun Microsystems Inc. 

Virtual Machine Version 


Heap Memory Size 


Elapsed Garbage Collection Time (milli seconds) 


Present Number of Classes Loaded 


Total Number of Classes Loaded 


Total Number of Classes Unloaded 

Number of Garbage Collections Occurred 

Number of Live Threads 

Number of Started Threads 

Peak Live Thread Count 

Most of these statistics are not tunable. They provide information about the JVM's operation.

Another source of tuning information on the JVM is the package, which provides the management interface for monitoring and management of the JVM. For more information on this package, see

Java Heap Tuning

As with all Java programs, the performance of the web applications in the Web Server is dependent on the heap management performed by the JVM. Balancing times and throughput is a challenge. For more information, read the performance documentation for the Java HotSpot virtual machine, which can be found at

Specific documents of interest include “Tuning Garbage Collection with the 5.0 Java Virtual Machine” and “Ergonomics in the 5.0 Java Virtual Machine”.

JVM options can be specified in the Admin Console on the configuration's Java tab ⇒ JVM Settings sub tab. In the CLI, use the wadm commands set-jvm-prop and set-jvm-profiler-prop.