Question

I have an ant script that is executing a jmx get task:

<jmx:get
                name="java.lang:type=GarbageCollector,name=Copy" 
                attribute="LastGcInfo"
                resultproperty="CopyLastGcInfo"
                />

Now, the LastGcInfo attribute has a map Map called memoryUsageBeforeGC. In this map there is a pair with a key called “value”. Althoug I am unable to elicit it and print it out. I have tried to accomplish it like that:

    <echo>${CopyLastGcInfo.memoryUsageBeforeGc.value.used}</echo>
    <echo>${CopyLastGcInfo.memoryUsageBeforeGc.0.used}</echo>
    <echo>${CopyLastGcInfo.memoryUsageBeforeGc.used}</echo>

That didn’t work. Do you have any suggestions how to tackle this problem?

Thanks.

Answer 1

The following example worked for me:

<project name="Catalina Ant JMX" xmlns:jmx="antlib:org.apache.catalina.ant.jmx" default="jmx">

    <target name="jmx" description="Show JMX stats">
        <jmx:open host="localhost" port="9012" username="controlRole" password="tomcat"/>

        <jmx:get name="java.lang:type=GarbageCollector,name=Copy" 
                 attribute="LastGcInfo"
                 resultproperty="CopyLastGcInfo"
                 echo="false"
                 />

        <echo>
        memoryUsageBeforeGc
        ===================
        Perm Gen.used=${CopyLastGcInfo.memoryUsageBeforeGc.Perm Gen.used}
        Tenured Gen.used=${CopyLastGcInfo.memoryUsageBeforeGc.Tenured Gen.used}
        Eden Space.used=${CopyLastGcInfo.memoryUsageBeforeGc.Eden Space.used}
        Code Cache.used=${CopyLastGcInfo.memoryUsageBeforeGc.Code Cache.used}
        Survivor Space.used=${CopyLastGcInfo.memoryUsageBeforeGc.Survivor Space.used}
        </echo>
    </target>

</project>

Example output

jmx:
     [echo] 
     [echo]         memoryUsageBeforeGc
     [echo]         ===================
     [echo]         Perm Gen.used=9660888
     [echo]         Tenured Gen.used=8393792
     [echo]         Eden Space.used=4456448
     [echo]         Code Cache.used=2038016
     [echo]         Survivor Space.used=172784
     [echo]         

Note

• The “echo” attribute of the “jmx:query” task can be used to see the ANT properties and values created by the task. Useful for troubleshooting.