GC Config Simulation Panel

Simulation is available only for the data collected with the -Xverbosegc option, available only for Java 2 JRE and SDK for HP-UX, version 1.3.x, or later.

This panel allows you to experiment with JVM heap sizing parameters.  To perform a simulation, move one or more of the sliders to the desired value and click the Create Simulation button.  A new data file, called sim.txt, will be created with the results of the simulation.  Open this file as a normal data capture file in HPjtune to analyze the effect of the parameters you chose.

Two of the sliders on this screen are interrelated.  When you move the slider for Total Heap Size, the slider for New Generation Size is automatically set to the recommended value.  However, after selecting your desired Total Heap Size, you can independently adjust the New Generation Size slider without affecting Total Heap Size.

At the bottom of the GC Config Simulation Panel is a text window showing the JVM command line options that match the slider settings and other choices you have made for your simulation.  These are the options you should use to validate your simulation with a new test run of your application.  You can cut and paste this text from HPjtune into your command window using standard mouse actions.

If your data collection file includes garbage collection events due to application calls to the System.gc() method, a checkbox will appear allowing you to decide if you want these calls disabled in your simulation.  This corresponds to the -XX:+DisableExplicitGC JVM command line option, which will appear in the JVM options text box if you choose to disable these calls.  Using this option in an application run will match the conditions of the simulation if you choose to disable these calls.