Tivoli Monitoring, Version 6.2

Tuning the portal client JVM

The memory usage of the portal client JVM increases as the size of the monitoring environment increases. If the maximum Java™ heap size setting is too low, the JVM will spend a significant amount of time performing garbage collection. This can result in poor portal client response time and high CPU utilization.

The default value for the maximum Java heap size differs by client type, as shown in Table 6 below.

Table 6. Default Java heap size parameters by portal client type
Client type Initial Java heap size (-Xms) Maximum Java heap size (-Xmx) Where specified
Browser (Internet Explorer) 4 MB

increase to 128 MB

64 MB

increase to 256 MB

IBM® Control Panel for Java
Desktop 128 MB 256 MB
  • cnp.bat (Windows®)
  • cnp.sh (Linux®)
  • in install_dir/CNP
Java Web Start Desktop client 128 MB 256MB tep.jnlp file on portal server

For the desktop client and Java Web Start desktop client, the default maximum Java heap size is 256MB, which is a good setting for most environments.

For the browser client, the Java Plug-in has a default maximum Java heap size of 64MB on Windows, which is too low. The Tivoli Enterprise™ Portal browser client uses the IBM Java Plug-in, which is automatically installed on your computer with the Tivoli Enterprise Portal. If the Java heap size parameters are not set properly, browser client performance will be slow and your workstation may receive HEAPDUMP and JAVACore files, an out-of-memory condition, when you are logged on.

To receive good performance from the browser client, you must increase the Java heap size parameters from their default values. Before you start the browser client, take the following steps:

  1. In the Windows Control Panel, open the Java Control Panel.

  2. If you have multiple Java versions, verify that you have the correct control panel open by confirming the Java Runtime is Version 1.5 and that the JRE is in the IBM path (such as c:\program files\IBM\Java50\jre\bin). To verify, click on the Java(TM) tab and check the Location column for the JRE.

  3. Set the Java Runtime Parameters:

    1. Click the Java tab.
    2. Click the Java Applet Runtime Settings View button.
    3. Double-click the Java Runtime Parameters field and enter -Xms128m -Xmx256m -Xverify:none.
    4. Click OK.

    The -Xms128m specifies the starting size of the Java heap (128 MB) and -Xmx256m specifies the maximum size.

  4. Confirm that the Temporary Files settings are set to Unlimited:

    1. Click the General tab.
    2. Click Settings.
    3. Select Unlimited for the Amount of disk space to use.
    4. Click OK.
  5. Clear the browser cache:

    1. In the General tab, click Delete Files.
    2. In the window that opens, select Downloaded Applets and click OK.

With either the desktop or browser client, if you observe symptoms of heap memory exhaustion using a maximum Java heap size setting of 256 MB, increase the maximum setting in increments of 64 MB until the symptoms disappear.

Make sure the client workstation has enough memory to handle the maximum heap size. To determine if the client workstation has sufficient memory, observe the available physical memory (as shown on the Windows Task Manager Performance tab) when the workstation is not running the Tivoli Enterprise Portal client, but is running any other applications that need to run concurrently with the portal client. Verify that the client workstation has enough available physical memory to hold the entire maximum Java heap size for the Tivoli Enterprise Portal plus another 150 MB. The additional 150 MB provides an allowance for non-Java heap storage for the Tivoli Enterprise Portal and extra available memory for use by the operating system.

For more information on Java memory management and Java heap tuning parameters, please refer to the IBM Developer Kit and Runtime Environment, Java 2 Technology Edition, Version 5.0 Diagnostics Guide (SC34-6650).


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