ActiveMQ DefaultMessageListenerContainer Why Only One Connection? - spring

Question

<bean id="amqConnectionFactory" class="org.apache.activemq.ActiveMQConnectionFactory">
<property name="brokerURL" value="${mq.activemq.host}" />
<property name="userName" value="${mq.activemq.user}" />
<property name="password" value="${mq.activemq.pass}" />
<property name="maxThreadPoolSize" value="30" />
</bean>
<bean id="amqPooledConnectionFactory" class="org.apache.activemq.pool.PooledConnectionFactory" destroy-method="stop">
<property name="connectionFactory" ref="amqConnectionFactory" />
<property name="maxConnections" value="10" />
<property name="maximumActiveSessionPerConnection" value="300" />
<property name="idleTimeout" value="60000" />
</bean>
<bean id="queueListenerContainer" class="org.springframework.jms.listener.DefaultMessageListenerContainer">
<property name="connectionFactory" ref="amqPooledConnectionFactory" />
<property name="destination" ref="queueDestination" />
<property name="messageListener" ref="queueAwareMessageListener" />
<property name="taskExecutor" ref="queueListenerTaskExecutor" />
<property name="concurrency" value="5-30" />
</bean>
What is the relationship between maxThreadPoolSize, maxConnections, maximumActiveSessionPerConnection, and concurrency?
Why I set maxConnections = 10, but Listener only one Connector in the Connections, can't increase more?
The number of consumers is correct. It has 5 with initialization，and gradually increases with change.

Answer 1

The bottom line regarding the number of connections which will be used is determined by the org.springframework.jms.listener.DefaultMessageListenerContainer which you have configured (since that is the only component here actually creating connections). As far as I can tell it will only ever create a single connection so using a connection pool here appears pointless. The concurrency parameter simply controls the concurrent number of consumers on the connection.
By setting maxConnections = 10 on the org.apache.activemq.pool.PooledConnectionFactory you are just limiting the size of the connection pool. However, since the queueListenerContainer won't ever call createConnection() more than once it doesn't really matter.
You can read about the maxThreadPoolSize of the org.apache.activemq.ActiveMQConnectionFactory in the ActiveMQ documentation.