Performance Tuning for Content Manager

Chapter 11. Performance monitoring, analysis, and tracing 343

<GC(43): refs: soft 0 (age >= 32), weak 0, final 23, phantom 0>

<AF[43]: completed in 75 ms>

A healthy JVM under a workload should keep the free memory percentage

somewhat constant. It decreases then increases after garbage collection is done.

If the 45% free (1064221992/1073740288) percentage goes down over time to

near zero, the JVM might hang or report an “out of memory” error, an indication

that your application either has a large memory footprint or has memory leaks.

More debugging is needed to determine what is causing the problem.

11.5.3 Java Virtual Machine Profiler Interface

The Tivoli Performance Viewer leverages a Java Virtual Machine Profiler

Interface (JVMPI) to enable more comprehensive performance analysis. This

profiling tool enables the collection of information, such as data about garbage

collection, and the JVM API that runs the application server.

JVMPI is a two-way function call interface between the JVM API and an

in-process profiler agent. The JVM API notifies the profiler agent of various

events, such as heap allocations and thread starts. The profiler agent can activate

or deactivate specific event notifications based on the needs of the profiler.

JVMPI supports partial profiling by enabling the user to choose which types of

profiling information to collect and to select certain subsets of the time during

which the JVM API is active. JVMPI moderately increases performance impact.

Enabling Java Virtual Machine Profiler Interface data reporting

To enable JVMPI data reporting for each individual application server:

1. Open the administrative console.

2. Click Servers → Application Servers in the console navigation tree. Select

the application server for which JVMPI must be enabled.

3. Click Process Definition. Then click Java Virtual Machine.

4. Type -XrunpmiJvmpiProfiler in the Generic JVM arguments field.

5. Click Apply or OK. Click Save.

6. This returns you to the window from step 2. Click the Configuration tab.

When in the Configuration tab, settings will apply when the server is restarted.

When in the Runtime Tab, settings apply immediately. Note that Performance

Monitoring Service can be enabled only in the Configuration tab.

7. Click Performance Monitoring Service and select the Startup checkbox.

8. Set initial specification level to Custom and jvmRuntimeModule=X.