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Configuring the JMX Monitoring Service

There are two ways to configure the JMX Monitoring Service:

  1. Using the set-monitoring-configuration asadmin command

  2. Editing the domain.xml file directly.

Examples on how to use the service to monitor the HeapMemoryUsage attribute using both methods are shown below, but it is first worth noting the default configuration values for the service:

  • enabled: false, valid type: Boolean

  • amx: false, valid type: Boolean, optional

  • logfrequency: 15, valid type: Long, optional

  • logfrequencyunit: SECONDS, valid type: TimeUnit, optional

Monitoring attributes are added to the service as properties of the configuration and contain the following values:

  • name: the MBean attribute name

  • value: the MBean domain name

  • description: displayed in the get-monitoring-configuration asadmin command, optional

Using the asadmin command

Adding the monitoring attribute

To add the HeapMemoryUsage attribute to the list of MBean attributes to monitor using the service the following command can be used:

asadmin> set-monitoring-configuration --addproperty 'name=HeapMemoryUsage value=java.lang:type=Memory' --enabled false

Breaking this command down, two options have been used:

  • --addproperty

  • --enabled

Passing --addproperty to set-monitoring-configuration provides a way to add a new MBean attribute to monitor using the service. The option takes in a string of space-delimited key-value pairs corresponding to the values listed earlier. The name and value fields are required, but description is not. Providing name=HeapMemoryUsage denotes that the name of the MBean attribute to log is HeapMemoryUsage, while value=java.lang:type=Memory denotes the ObjectName of the MBean to look for the attribute on is java.lang:type=Memory.

The second option passed, --enabled, is the only required option for the asadmin command. The only valid values to give this option are true or false. Passing false to the option will disable the logging service on next startup if it is currently enabled, but will otherwise do nothing. Under this scenario the monitoring service has not been configured yet so false was passed to the option.

Dealing with composite MBean attributes

The MBean attribute added, HeapMemoryUsage, is a composite attribute. It has metrics for the commited, init, max and used attributes. The monitoring service will by default monitor each metric and log it as {$metric}{$attribute_name}:{$attribute_value}.

If this is not the desired result, it is possible to monitor a single metric for a composite MBean attribute. To monitor a single metric for the attribute the value of name passed to the --addproperty option should be modified like so:

name=HeapMemoryUsage.metric

So to log only the used heap memory the asadmin command would be:

asadmin> set-monitoring-configuration --addproperty 'name=HeapMemoryUsage.used value=java.lang:type=Memory' --enabled false

Setting logging frequency

There are two configuration attributes related to the frequency at which log messages are written: logfrequency and logfrequencyunit. The first is a numerical value used for the rate, while the second is the unit for the rate. The default configuration is set to have a message logged every 15 seconds.

If the value of logfrequencyunit is the default of SECONDS then to have the monitoring service log messages every one minute execute the following command:

asadmin> set-monitoring-configuration --logfrequency 60 --enabled false

Enabling the monitoring service

After configuring the monitoring service, there are two options to enable it. The service can either be enabled for next startup or the service can be dynamically enabled on a running instance of Payara (provided a non-empty configuration exists at server startup). To enable the service dynamically on the default running instance of Payara the command to run is:

asadmin> set-monitoring-configuration --dynamic true --enabled true

To enable the service for next startup the --dynamic option would need to be dropped from the command.

Editing the domain.xml file

To configure the monitoring service by editing the domain.xml file, it’s useful to know about the structure of the <monitoring-service-configuration> tag first:

<monitoring-service-configuration enabled="true" logfrequency="60">
  <property name="Attribute1" value="MBean1"></property>
  <property name="Attribute2" value="MBean2"></property>
</monitoring-service-configuration>

The <monitoring-service-configuration> tag houses the configuration values in its attributes. Omitted values take the respective default value. If the configuration is edited while the server is running the service must be restarted for the configuration changes to be considered.

If the service has not yet run on the instance then the configuration tag will not have been created. To manually create it, the tag needs to be added to the domain.xml in the respective config section.

<configs>
  <config name="server-config">
    ...
    <monitoring-service-configuration>
    </monitoring-service-configuration>
    ...
  </config>
</configs>

Adding the monitoring attribute

MBean attributes to monitor are added to the configuration section as <property> tags. Each property tag can take values for name, value and description. To add an MBean attribute to monitor a <property> tag should be added as shown:

<monitoring-service-configuration>
  <property name="HeapMemoryUsage" value="java.lang:type=Memory"></property>
</monitoring-service-configuration>

Here all of the necessary attributes have been given to the tag, name and value. The value given to name should be the name of the MBean attribute to monitor, while the value given to value should be the ObjectName of the MBean to look for the MBean attribute on. Here the MBean attribute added is HeapMemoryUsage which resides in the MBean with the ObjectName of java.lang:type=Memory.

Dealing with composite MBean attributes

The MBean attribute added, HeapMemoryUsage, is a composite attribute. It has metrics for commited, init, max and used. The monitoring service will by default monitor each metric and log it as {$metric}{$attribute_name}:{$attribute_value}.

If this is not the desired result, it is possible to monitor a single metric for a composite MBean attribute. To monitor a single metric for the attribute the attribute of name for the property should be changed to:

name="HeapMemoryUsage.metric"

The configuration to log only the used heap memory the configuration would look like this:

<monitoring-service-configuration>
  <property name="HeapMemoryUsage.used" value="java.lang:type=Memory"></property>
</monitoring-service-configuration>

Setting logging frequency

There are two configuration attributes related to the frequency at which log messages are written: logfrequency and logfrequencyunit. The first is a numerical value used for the rate, while the second value is the unit for the rate. The default configuration is set to have a message logged every 15 seconds.

To have the monitoring service log messages every one minute change the tag as shown:

<monitoring-service-configuration logfrequency="60">
  <property name="HeapMemoryUsage" value="java.lang:type=Memory"></property>
</monitoring-service-configuration>

Enabling the monitoring service

Now that the service is configured, it can be enabled simply by adding enabled="true" to the configuration tag:

<monitoring-service-configuration enabled="true" logfrequency="60">
  <property name="HeapMemoryUsage" value="java.lang:type=Memory"></property>
</monitoring-service-configuration>