Best Practices for System Performance

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This section discusses settings that can optimize your supported application server. While these settings provide optimal performance in IBM test environments, your environment may require different settings. You can use these settings as a guideline or as a starting point, and then customize the settings to your specific environment requirements. For the latest supported application server versions and fix packs, always check the IBM TRIRIGA Compatibility Matrix.

6.1 General Recommendations

6.1.1 JVM Heap Size Values

You can use the following minimum heap size values to start tuning:

Java virtual machine (JVM) heap size parameters directly influence garbage collection (GC) behavior. Increasing the heap size permits more objects to be created before it triggers a garbage collection. However, a larger heap size means a larger amount of time is needed to find and process objects that need to be garbage collected. Consequently, JVM heap size tuning often involves a balance between the interval between garbage collections and the pause time needed to perform the garbage collection.

To tune the JVM heap size, enable verbose GC. When enabled, the JVM prints out useful information at each garbage collection, such as the amount of free and used bytes in the heap, the interval between garbage collections, and the pause time. This information can then be used to analyze the heap usage.