Sun Microsystems 820434310 manual Tuning the Java Runtime System, Java Virtual Machine Settings

C 4H A P T E R 4

Tuning the Java Runtime System

This chapter discusses the following topics:

■“Java Virtual Machine Settings” on page 83

■“Managing Memory and Garbage Collection” on page 84

■“Further Information” on page 91

Java Virtual Machine Settings

J2SE 5.0 provides two implementations of the HotSpot Java virtual machine (JVM):

■The client VM is tuned for reducing start-up time and memory footprint. Invoke it by using the -client JVM command-line option.

■The server VM is designed for maximum program execution speed. Invoke it by using the -server JVM command-line option.

By default, the Application Server uses the JVM setting appropriate to the purpose:

■Developer Profile, targeted at application developers, uses the-client JVM flag to optimize startup performance and conserve memory resources.

■Enterprise Profile, targeted at production deployments, uses the default JVM startup mode. By default, Application Server uses the client Hotspot VM. However, if a server VM is needed, it can be specified by creating a <jvm-option> named “-server.”

You can override the default by changing the JVM settings in the Admin Console under Configurations > config-name> JVM Settings (JVM Options).

For more information on server-class machine detection in J2SE 5.0, see Server-Class Machine Detection .

For more information on JVMs, see JavaTM Virtual Machines.

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