Memory thrash is caused when a large number of temporary objects are created in very short intervals. Although these objects are temporary and are eventually cleaned up, the garbage collection mechanism may struggle to keep up with the rate of object creation. This may cause application performance problems. Monitoring the time spent in garbage collection can provide insight into performance issues, including memory thrash.

For example, an increase in the number of spikes for major collections either slows down a JVM or indicates potential memory thrash. Use object instance tracking to isolate the root cause of the memory thrash. To configure and enable object instance tracking, see Object Instance Tracking for Java.

Splunk AppDynamics automatically tracks object instances for the top 20 core Java (system) classes and the top 20 application classes.

The Object Instance Tracking subtab provides the number of instances for a particular class and graphs the count trend of those object in the JVM. It provides the shallow memory size (the memory footprint of the object and the primitives it contains) used by all the instances.