java - 如何激活ActiveMQ持久化来抵抗重启？

Question

我确实知道 ActiveMQ 支持数据持久性(http://activemq.apache.org/persistence.html)，但我不明白如何让它工作，结果是当我重新启动 ActiveMQ 时，所有消息都消失了，而队列和主题仍然存在。

我读过有关在数据库上启用持久性的信息，但我想将数据保留在文件系统上，因为我的系统正面临数据库性能问题。

这是我的activemq.xml

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<!-- START SNIPPET: example -->
<beans
  xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.springframework.org/schema/beans 
http://www.springframework.org/schema/beans/spring-beans.xsd
  http://activemq.apache.org/schema/core 
http://activemq.apache.org/schema/core/activemq-core.xsd">

<!-- Allows us to use system properties as variables in this configuration file -->
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="locations">
        <value>file:${activemq.conf}/credentials.properties</value>
    </property>
</bean>
<!-- Allows accessing the server log -->
<bean id="logQuery" class="io.fabric8.insight.log.log4j.Log4jLogQuery"
      lazy-init="false" scope="singleton"
      init-method="start" destroy-method="stop">
</bean>

<!--
    The <broker> element is used to configure the ActiveMQ broker.
-->
<broker xmlns="http://activemq.apache.org/schema/core" brokerName="localhost" dataDirectory="${activemq.data}">

    <destinationPolicy>
        <policyMap>
          <policyEntries>
            <policyEntry topic=">" >
                <!-- The constantPendingMessageLimitStrategy is used to prevent
                     slow topic consumers to block producers and affect other consumers
                     by limiting the number of messages that are retained
                     For more information, see:

                     http://activemq.apache.org/slow-consumer-handling.html

                -->
              <pendingMessageLimitStrategy>
                <constantPendingMessageLimitStrategy limit="1000"/>
              </pendingMessageLimitStrategy>
            </policyEntry>
          </policyEntries>
        </policyMap>
    </destinationPolicy>


    <!--
        The managementContext is used to configure how ActiveMQ is exposed in
        JMX. By default, ActiveMQ uses the MBean server that is started by
        the JVM. For more information, see:

        http://activemq.apache.org/jmx.html
    -->
    <managementContext>
        <managementContext createConnector="false"/>
    </managementContext>

    <!--
        Configure message persistence for the broker. The default persistence
        mechanism is the KahaDB store (identified by the kahaDB tag).
        For more information, see:

        http://activemq.apache.org/persistence.html
    -->
    <persistenceAdapter>
        <kahaDB directory="${activemq.data}/kahadb"/>
    </persistenceAdapter>


      <!--
        The systemUsage controls the maximum amount of space the broker will
        use before disabling caching and/or slowing down producers. For more information, see:
        http://activemq.apache.org/producer-flow-control.html
      -->
      <systemUsage>
        <systemUsage>
            <memoryUsage>
                <memoryUsage percentOfJvmHeap="70" />
            </memoryUsage>
            <storeUsage>
                <storeUsage limit="100 gb"/>
            </storeUsage>
            <tempUsage>
                <tempUsage limit="50 gb"/>
            </tempUsage>
        </systemUsage>
    </systemUsage>

    <!--
        The transport connectors expose ActiveMQ over a given protocol to
        clients and other brokers. For more information, see:

        http://activemq.apache.org/configuring-transports.html
    -->
    <transportConnectors>
        <!-- DOS protection, limit concurrent connections to 1000 and frame size to 100MB -->
        <transportConnector name="openwire" uri="tcp://0.0.0.0:61616?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
        <transportConnector name="amqp" uri="amqp://0.0.0.0:5672?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
        <transportConnector name="stomp" uri="stomp://0.0.0.0:61613?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
        <transportConnector name="mqtt" uri="mqtt://0.0.0.0:1883?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
        <transportConnector name="ws" uri="ws://0.0.0.0:61614?maximumConnections=1000&amp;wireFormat.maxFrameSize=104857600"/>
    </transportConnectors>

    <!-- destroy the spring context on shutdown to stop jetty -->
    <shutdownHooks>
        <bean xmlns="http://www.springframework.org/schema/beans" class="org.apache.activemq.hooks.SpringContextHook" />
    </shutdownHooks>

</broker>

<!--
    Enable web consoles, REST and Ajax APIs and demos
    The web consoles requires by default login, you can disable this in the jetty.xml file

    Take a look at ${ACTIVEMQ_HOME}/conf/jetty.xml for more details
-->
<import resource="jetty.xml"/>

Answer 1

为了在代理上启用持久性，您必须选择一个持久性适配器。您已通过在 activemq.xml 中指定要使用 KahaDB 来完成此操作。

<broker brokerName="broker" persistent="true" ...>
    <persistenceAdapter>
         <kahaDB directory="${activemq.data}/kahadb"/>
    </persistenceAdapter>
</broker>

好的，现在 broker 知道你想要持久化传入的消息，但是客户端仍然可以覆盖这个设置。为此，您需要在发送消息时指定要保留它。检查您用于发送消息的机制，并确保将它们设置为持久化。

例如如果您使用 Spring 的 JmsTemplate 发送消息，则必须调用 setDeliveryPersistent(...) .这只是一个示例，请注意此方法的默认值是 “true”，也就是传递模式“PERSISTENT”。