Performance Tuning for Content Manager

Chapter 9. Tuning WebSphere for Content Manager 273

9.5.7 Security

Security is a global setting. When security is enabled, the performance can

decrease between 10 to 20 percent.

Default values

Disabled

How to view or set

1. In the administrative console click Security → Global Security.

2. Select Enabled and Enforce Java 2 Security setting.

3. Click Apply to ensure that the changes are saved.

4. Stop and restart the application server.

Our recommendation

When security is not needed, keep the default disable setting.

9.6 Java virtual machines tuning

Java virtual machines (JVM) offer several tuning parameters that affect the

performance of WebSphere Application Servers and application performance.

In this section, we discuss the performance tuning settings associated with JVM.

9.6.1 Initial and maximum heap size for the JVM

These parameters set the initial and the maximum heap sizes for the JVM.

In general, increasing the size of the Java heap improves throughput until the

heap no longer resides in physical memory. After the heap begins swapping to

disk, Java performance drastically suffers. Therefore, the maximum heap size

must be low enough to contain the heap within physical memory. The physical

memory usage must be shared between the JVM and the other applications,

such as the database. For assurance, use a smaller heap, for example 64 MB, on

machines with less memory.

Default values

 Initial heap size: 0 MB

 Maximum heap size 256 MB

How to view or set

1. Click Servers → Application Servers.

274 Performance Tuning for Content Manager

2. Click the application server you want to tune.

3. Under Additional Properties, click the Process Definition.

4. Under Additional Properties, click Java Virtual Machine.

5. Enter values in the General Properties field for the following fields: Initial

Heap Size and Maximum Heap Size.

6. Save your changes.

7. Restart the application server.

Our recommendation

Try a maximum heap of 128 MB on systems with less than 1 GB of physical

memory, 256 MB for systems with 2 GB memory, and 512 MB for larger systems.

The starting point depends on the application.

For production systems where the working set size of the Java applications is not

well understood, an initial setting of one-fourth the maximum setting is a good

starting value. The JVM will then try to adapt the size of the heap to the working

set of the Java application.

Monitor your system. When you have verified the normal size of your JVM heap

size, change the initial heap size to this value using the Tivoli Performance

Viewer.