Configuration of JvmMemPoolGCTest

While the JvmGCDetailsTest test reports statistics indicating how well each collector on the JVM performs garbage collection, the measures reported by the JvmMemPoolGCTest test help assess the impact of the garbage collection activity on the availability and usage of memory in each memory pool of the JVM. Besides revealing the count of garbage collections per collector and the time taken by each collector to perform garbage collection on the individual memory pools, the test also compares the amount of memory used and available for use pre and post garbage collection in each of the memory pools. This way, the test enables administrators to guage the effectiveness of the garbage collection activity on the memory pools, and helps them accurately identify those memory pools where enough memory could not reclaimed or where the garbage collectors spent too much time.

Note:

This test will work only if the target Java application uses the JDK/JRE offered by one of the following vendors: Oracle, Sun, OpenJDK. IBM JDK/JRE is not supported.

The default parameters associated with this test are as follows:

• The TEST PERIOD list box helps the user to decide how often this test needs to be executed.

• In the HOST text box, the host name of the server for which the test is to be configured has to be specified.

• The port number at which the specified HOST listens should be specified in the PORT listbox.

• This test allows you the option to collect the desired metrics using one of the following methodologies:

  • By contacting the Service URL of the application via JMX

  • Using GC logs

  To use JMX for metrics collections, set the MEASURE MODE to JMX.

  On the other hand, if you intend to use the GC log files for collecting the required metrics, set the MEASURE MODE to Log File. In this case, you would be required to enable GC logging. The procedure for this has been detailed in Monitoring IBM Websphere Liberty document. 

• The JREHOME parameter will be available only if the MEASURE MODE is set to Log File. Specify the full path to the Java Runtime Environment (JRE) used by the target application.

• The LOGFILENAME parameter will be available only if the MEASURE MODE is set to Log File. Specify the full path to the GC log file to be used for metrics collection.

• For the eG agent to collect metrics from the target IBM WebSphere Liberty server, the local connector should be enabled on the target server. Once the connector is enabled, a com.ibm.ws.jmx.local.address file will be created in the ${server.output.dir}/logs/state folder. The eG agent uses this file to connect to the target server and collect the required metrics from it. Therefore, specify the exact path to this file in the SERVICE URL PATH text box. For example, in case of Windows environments, the Service URL Path can be C:\wlp\usr\servers\server1\logs\state and in case of Linux environments, the SERVICE URL PATH can be /opt/wlp/ur/servers/server1/logs/state.

• Specify the duration (in seconds) for which this test should wait for a response from the target Java application. If there is no response from the target beyond the configured duration, the test will timeout. By default, the TIMEOUT parameter is set to 240 seconds.

• If multiple components of the same component type are awaiting configuration, then an APPLY TO OTHER COMPONENTS check box will appear in this page. Clicking on this check box will allow you to apply the configuration to all/selected components of that type.

• Once the necessary values have been provided, clicking on the UPDATE button will register the changes made.

When changing the configuration for specific servers, a “*” beside the text box corresponding to the parameter signifies that these values have to be manually configured by the user. The parameter values that require to be configured will typically be prefixed with a “$“ or contain a series of “*”. A value of "none" in the parameter value indicates that the corresponding parameter value can be changed if required.