Figure 3-1 Heap Display Showing Possible Memory Leak BehaviorSee also Heap Usage Notification (page 111).

The Pi sample program uses a simple Java program that allocates some arrays, thereby exhibiting the behavior of a memory-leaking application. The demo application is available from the HPjmeter installation directory:

Source: $JMETER_HOME/demo/Pi.java

Binary: $JMETER_HOME/demo/Pi.jar

Use -jar Pi.jar with the run_simple_jvmagent script to start the sample. When measuring the sample application, allow considerable time for the heap to mature and stabilize, and for the JVM agent to collect memory leak data. Eventually, you will see two alerts:

•Expected Out Of Memory Error Alert (page 110) with the leaking rate.

•Array Leak Locations Alert (page 112) with the leak location.

When the default garbage collectors and heap size for Java HotSpot Virtual Machine 1.5.0.07 are used, the detection of a memory leak for this demonstration program occurs after about 90 minutes. This time can be substantially longer when using a different JVM or nonstandard garbage collector or heap settings.

In real situations, the detection time depends on the maximum heap size, the size of the leak, the application running time, and the application and load characteristics. Typically, the detection will occur in about two hours.

Here is an Array Leak alert for the sample program:

Thread Deadlock Sample

This sample application demonstrates how HPjmeter detects deadlocked threads.

34 Getting Started