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Liberty

Adding JVM options​

The following explains how to add required JVM options to effectively use the Java monitoring agent in the Liberty application server environment.

In the jvm.options file, add the agent option. If no file, create a new one.

-javaagent:/app/whatap/whatap.agent-2.1.1.jar
-Dorg.osgi.framework.bootdelegation=whatap.* ## Additional options for OSGI framework configuration ##
Note

In case of Java 17 or later, add the following options for reflection.


--add-opens=java.base/java.lang=ALL-UNNAMED

Viewing the heap histogram​

WhaTap's Java Monitoring provides the function to view the status of heap occupancy objects in the JVM memory (sizes for each object in heap memory). In APP > Instance performance analysis, select the Heap histogram tab.

Java versions 6 to 8 support basic functions without the JVM options. However, for some Java versions, the JVM options must be applied as follows:

  • Java 9 to Java 15

    -Djdk.attach.allowAttachSelf=true
    example
    java -javaagent:{WHATAP_HOME}/whatap.agent-X.Y.Z.jar -Djdk.attach.allowAttachSelf=true -jar {application.jar}

  • Java 16 or later

    -Djdk.attach.allowAttachSelf=true
    --add-opens=jdk.attach/sun.tools.attach=ALL-UNNAMED
    example
    java -javaagent:{WHATAP_HOME}/whatap.agent-X.Y.Z.jar -Djdk.attach.allowAttachSelf=true --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=jdk.attach/sun.tools.attach=ALL-UNNAMED -jar {application.jar}
Note

It does not support Java 5 or earlier and IBM Java.

Next steps​

  • Open source tracing

    Depending on the framework or open source library used in applications, you may need to add agent options. For example, when using spring-boot-3.x, feign-client-11, or okhttp3-4.4 with a framework or open source, set the options as follows:

    whatap.conf
    weaving=spring-boot-3.0,feign-11,okhttp3-4.4

    For information on how to configure the framework or open source library that suits your application environment, see the following.

  • Checking the installation

    If you have created a project, installed an agent, and applied all JVM options, see the checklist in the following.

  • Installation troubleshooting

    It provides various problems that may occur when installing the agent and specific instructions for resolving them. It provides solutions against various situations, including firewall configuration, SpringBoot and Tomcat JMX configuration, and server configuration using the OSGI framework. For more information, see the following.

  • Agent setting

    It provides various features for monitoring by applying some options to the agent configuration file (whatap.conf). It includes basic configuration, configuration for server connection and data transfer, how to manage the configuration files for multiple application servers, and transaction tracing, and more. For more information, see the following.

  • Starting the monitoring

    After all settings are made, restart the application server. The agent starts collecting data. First, check whether the monitoring data has been collected in Application Dashboard. For more information about Application Dashboard, see the following.