The Java Agent excludes system classes like java.lang.* from instrumentation by default. To enable instrumentation for a system class, use an agent configuration property as described here:
Instrumented system classes add to the resource overhead introduced by the agent. The amount of overhead depends on the number of calls to the classes. AppDynamics recommends that you instrument a few nodes first and monitor the performance for these nodes before configuring all nodes in your system.
To instrument a Java system class:
- Open the <agent_home>/conf/app-agent-config.xml file for the node where you want to enable instrumentation.
- Add an <override-system-exclude> element with the fully qualified system class name to be instrumented in the <bci-processing-excludes> element. <override-system-exclude> element is used to whitelist classes (for example, 'com.sun.jersey') for instrumentation despite a blacklist ('com.sun.*').
- Restart the JVM for which you have modified the XML file.
Once you restart the JVM, the package will be included in the instrumentation.