ActiveMQ 使用KahaDB存储时，默认的配置是所有队列都存在一个KahaDB内。使用久了会发现一个问题，就是DB文件越来越大，几十上百G。主要原因是当队列内只要有一条消息没有被消费掉，那么ActiveMQ是不会清理KahaDB的文件的。

为此，我们可以加一个过滤器，配置成每个队列一个KahaDB，来缓解这个问题，配置如下：

        <persistenceAdapter>
           <mKahaDB directory="${activemq.data}/kahadb">
            <filteredPersistenceAdapters>
                  <!-- kahaDB per destinations -->
              <filteredKahaDB perDestination="true">
                <persistenceAdapter>
                    <kahaDB ignoreMissingJournalfiles="true"  checkForCorruptJournalFiles="true"  checksumJournalFiles="true" />
                </persistenceAdapter>
              </filteredKahaDB>
             </filteredPersistenceAdapters>
           </mKahaDB>
        </persistenceAdapter>

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一个跑了满久的activemq停止后再启动就自动退出了，查看日志有以下报错：

2018-06-11 17:54:21,483 | WARN  | Some journal files are missing: [17496, 17495, 17494, 11811, 11807, 11793] | org.apache.activemq.store.kahadb.MessageDatabase | main
2018-06-11 17:54:21,704 | ERROR | [0:ExceptionDLQ.ActivityResultPostProcess] references corrupt locations. 10 messages affected. | org.apache.activemq.store.kahadb.MessageDatabase | m
ain
2018-06-11 17:54:21,706 | ERROR | Failed to start Apache ActiveMQ ([localhost, null], java.io.IOException: Detected missing/corrupt journal files referenced by:[0:ExceptionDLQ.Activit
yResultPostProcess] 10 messages affected.) | org.apache.activemq.broker.BrokerService | main
2018-06-11 17:54:21,711 | INFO  | Apache ActiveMQ 5.13.3 (localhost, null) is shutting down | org.apache.activemq.broker.BrokerService | main
2018-06-11 17:54:21,715 | INFO  | Connector openwire stopped | org.apache.activemq.broker.TransportConnector | main
2018-06-11 17:54:21,718 | INFO  | Connector amqp stopped | org.apache.activemq.broker.TransportConnector | main
2018-06-11 17:54:21,721 | INFO  | Connector stomp stopped | org.apache.activemq.broker.TransportConnector | main
2018-06-11 17:54:21,724 | INFO  | Connector mqtt stopped | org.apache.activemq.broker.TransportConnector | main
2018-06-11 17:54:21,727 | INFO  | Connector ws stopped | org.apache.activemq.broker.TransportConnector | main

解决方法：

把conf/activemq.xml文件内以下配置从：

        <persistenceadapter>
            <kahadb directory="${activemq.data}/kahadb"></kahadb>
        </persistenceadapter>

改成：

        <persistenceadapter>
            <kahadb directory="${activemq.data}/kahadb"
                    ignoreMissingJournalfiles="true"
                    checkForCorruptJournalFiles="true"
                    checksumJournalFiles="true"></kahadb>
        </persistenceadapter>

保存后退出。

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