Purpose of taskExecutor property in Spring's DefaultMessageListenerContainer

Question

The Spring's DefaultMessageListenerContainer (DMLC) has concurrentConsumer and taskExecutor property. The taskExecutor bean can be given corePoolSize property. What is then the difference between specifying concurrentConsumer and corePoolSize ? When concurrentConsumer property is defined it means that Spring will create specified number of consumer/messageListeners to process the message. When does corePoolSize comes into picture ?

Code snippet

<bean id="myMessageListener"
    class="org.springframework.jms.listener.DefaultMessageListenerContainer">
    <property name="connectionFactory" ref="connectionFactory" />
    <property name="destination" ref="myQueue" />
    <property name="messageListener" ref="myListener" />
    <property name="cacheLevelName" value="CACHE_CONSUMER"/>
    <property name="maxConcurrentConsumers" value="10"/>
    <property name="concurrentConsumers" value="3"/>
    <property name="taskExecutor" ref="myTaskExecutor"/>
</bean>

 <bean id="myTaskExecutor" class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor" >
    <property name="corePoolSize" value="100"/>
    <property name="maxPoolSize" value="100"/>
    <property name="keepAliveSeconds" value="30"/>
     <property name="threadNamePrefix" value="myTaskExecutor"/>
</bean>

Andrei Kovrov Andrei Kovrov · Accepted Answer · 2017-08-15T12:28:52

According to 4.3.6 version, the taskExecutor contains instances of AsyncMessageListenerInvoker which responsible for message processing. corePoolSize is a number of physical threads in the defined pool, while concurrentConsumer is a number of tasks in this pool. I guess this abstraction was designed for more flexible control.

Purpose of taskExecutor property in Spring's DefaultMessageListenerContainer

1 Answers