Default parameters for 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.

This page depicts the default parameters that need to be configured for the JvmMemPoolGCTest.

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

• 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.

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

When changing default configurations of tests, the values with "$" indicate variables that will be replaced by the eG system according to the specific server being managed - for instance, $hostName is the host/nickname of the target host, $port is the port number of the server being monitored. E.g., for a server xyz:80, $hostName will be changed automatically by the eG manager to "xyz" and $port will be changed to "80" when configuring a test.