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javajbossapache-camelactivemq-classic

Abnormal Behavior of Apache ActiveMQ on Multiple Consumer

I am using Jboss-fuse-6.3, with external Apache-activemq-5.15.2. I have bind 50 consumers on a queue, and on Active MQ portal in "Active Consumers" page, I have noticed that all 50 consumers are bind but message distribution on queues are not the same.

Screen shot is attached. On session id "1" En-queued message count is around 1010 but on other consumer sessions En-queued messages are only 10.

Im en-queuing messages from Apache Camel Route. Below is my Blueprint xml (Am i doing some thing wrong)

<bean class="org.apache.activemq.spring.ActiveMQConnectionFactory" id="connectionFactory">
    <property name="brokerURL" value="tcp://localhost:61616"/>
    <property name="userName" value="admin"/>
    <property name="password" value="admin"/>
    <property name="trustAllPackages" value="true"/>
</bean>
<bean class="org.apache.camel.component.jms.JmsConfiguration" id="jmsConfig">
    <property name="connectionFactory" ref="connectionFactory"/>
</bean>
<bean class="org.apache.activemq.camel.component.ActiveMQComponent" id="activemq">
    <property name="configuration" ref="jmsConfig"/>
</bean>

<bean class="org.apache.activemq.spring.ActiveMQConnectionFactory" id="connectionFactory">
    <property name="brokerURL" value="tcp://localhost:61616"/>
    <property name="userName" value="admin"/>
    <property name="password" value="admin"/>
    <property name="trustAllPackages" value="true"/>
</bean>
<bean class="org.apache.camel.component.jms.JmsConfiguration" id="jmsConfig">
    <property name="connectionFactory" ref="connectionFactory"/>
</bean>
<bean class="org.apache.activemq.camel.component.ActiveMQComponent" id="activemq">
    <property name="configuration" ref="jmsConfig"/>
</bean>
<!-- ENQUEUEING MESSAGES -->
<to pattern="InOnly" uri="activemq:queue:MyQueue"/>

<!-- DEQUEUEING MESSAGES -->
<fromuri="activemq:queue:MyQueue?concurrentConsumers=50"/>

enter image description here

Solution

  • This appears to be normal prefetching behavior on the part of the JMS client. If you want competing consumers with fair dispatching then you need to lower the prefetch level as the first consumer that connects will often get a higher number of message dispatched to it because the default prefetch is 1000 for a Queue consumer.

    Client URI can control the prefetch value:

    tcp://localhost:61616?jms.prefetchPolicy.queuePrefetch=1

    Read more about ActiveMQ consumer prefetch here.