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

- Previous: Chapter 3 Tuning the Application Server
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# 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:

- Platform Edition, targeted at application developers, uses the `-client` JVM flag to optimize startup performance and conserve memory resources.

- Enterprise Edition, targeted at production deployments, uses the default JVM startup mode. With J2SE 5.0, the HotSpot VM provides server-class machine detection, which will use the server VM if it detects “server-class” hardware (at least two CPUs and two GB of physical memory).

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.

- Previous: Chapter 3 Tuning the Application Server
- Next: Managing Memory and Garbage Collection

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