How to process CASes produced by CAS Multiplier concurrently - uima

Question

I am implementing UIMA pipeline with CASMultiplier and UIMA AS. I have a Segmenter Analysis Engine (A CASMultiplier) and a Analysis Engine (Annotator A). I created a Aggregate Analysis Engine of the Segmenter and Annotator A, and then I create a UIMA AS Deployment descriptor file with intention, the Segmenter produces CASes, and then the Annotator A process with CASes concurrently. The contents of the aggregate analysis engine descriptor file and the deployment descriptor file are as following:
AAE descriptor file:
<analysisEngineDescription xmlns="http://uima.apache.org/resourceSpecifier">
<frameworkImplementation>org.apache.uima.java</frameworkImplementation>
<primitive>false</primitive>
<delegateAnalysisEngineSpecifiers>
<delegateAnalysisEngine key="Segmenter">
<import location="../cas_multiplier/SimpleTextSegmenter.xml"/>
</delegateAnalysisEngine>
<delegateAnalysisEngine key="AnnotatorA">
<import location="AnnotatorA.xml"/>
</delegateAnalysisEngine>
</delegateAnalysisEngineSpecifiers>
<analysisEngineMetaData>
<name>Segmenter and AnnotatorA</name>
<description>Splits a document into pieces and runs Annotator on each
piece independently. All segments are output.</description>
<configurationParameters/>
<configurationParameterSettings/>
<flowConstraints>
<fixedFlow>
<node>Segmenter</node>
<node>AnnotatorA</node>
</fixedFlow>
</flowConstraints>
<capabilities>
<capability>
<inputs/>
<outputs>
<type allAnnotatorFeatures="true">com.trang.uima.types.Target</type>
<type allAnnotatorFeatures="true">com.eg.uima.types.IntermediateResult</type>
</outputs>
<languagesSupported>
</languagesSupported>
</capability>
</capabilities>
<operationalProperties>
<modifiesCas>true</modifiesCas>
<multipleDeploymentAllowed>true</multipleDeploymentAllowed>
<outputsNewCASes>true</outputsNewCASes>
</operationalProperties>
</analysisEngineMetaData>
</analysisEngineDescription>
Deployment descriptor file:
<?xml version="1.0" encoding="UTF-8"?><analysisEngineDeploymentDescription xmlns="http://uima.apache.org/resourceSpecifier">
<name>SegmenterAndBackTranstion</name>
<description>Deploys Segmenter and BackTranskation with 3 instances of BackTransation</description>
<version/>
<vendor/>
<deployment protocol="jms" provider="activemq">
<casPool numberOfCASes="5" initialFsHeapSize="2000000"/>
<service>
<inputQueue endpoint="SegmentAnBackTranslationQueue" brokerURL="tcp://localhost:61616" prefetch="0"/>
<topDescriptor>
<import location="../../descriptors/langrid_uima/SegmenterAndBackTranslationAE.xml"/>
</topDescriptor>
<analysisEngine async="false">
<scaleout numberOfInstances="5"/>
<casMultiplier poolSize="8" initialFsHeapSize="2000000" processParentLast="false"/>
<asyncPrimitiveErrorConfiguration>
<processCasErrors thresholdCount="0" thresholdWindow="0" thresholdAction="terminate"/>
<collectionProcessCompleteErrors timeout="0" additionalErrorAction="terminate"/>
</asyncPrimitiveErrorConfiguration>
</analysisEngine>
</service>
</deployment>
</analysisEngineDeploymentDescription>
After have this setting, I run the pipeline, however, it seems the CASes are process synchronously, one at a time.
Could anyone tell me, what am doing wrong? Is there a way to process CASes produced by CASMultiplier concurrently?
Thank you very much!