activemq热备与消息丢失
1. 解压 tar -zxvf apache-activemq-5.12.0-bin.tar.gz
2. 改名 mv apache-activemq-5.12.0 activemq
3. cd activemq/bin
4. 启动 ./activemq start
5. 访问 ip:8161/admin
/* 楼主本地的虚拟机这么安装没问题，可是远程的服务器安装却启动失败
* 如果启动报错的话，可以通过 ./activemq console查看启动信息
* 我启动失败是应为主机名不合法， 通过 hostname 命令可以查看当前主机名
* hostnamectl set-hostname newname设置新的主机名
* hostnamectl –static set-hostname newname设置静态名字
* 使用 reboot 重启之后， 就是新的名字了 (名字最好是简短的纯英文)
*/
消息丢失：如果在.5机器发送了2条消息，然后用.6机器去消费1条；这个时候对于.5机器来说.6就是一个客户端，它拿走了2条消息消费了一条还剩一条待消费。而此时剩下的一条只能通过.6机器消费，无法通过.5拿到消息。这样就达不到高性能的目的，我们可以通过消息回流来解决。
activemq热备配置(可以是n台，我以2台为例，灰色部分都是默认配置文件)：vim activemq/conf/activemq.xml
<!-- 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:${activemq.conf}/credentials.properties</value>
</property>
</bean>
<!-- Allows accessing the server log -->
<bean id="logQuery" class="io.fabric8.insight.log.log4j.Log4jLogQuery"
lazy-init="false" scope="singleton"
init-method="start" destroy-method="stop">
</bean>
<broker xmlns="http://activemq.apache.org/schema/core" brokerName="localhost" dataDirectory="${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>
<!-- 消息回流：加这段配置就不会出现消息丢失的情况(有中文会启动失败) 这段注释要删掉 -->
<policyEntry queue=">" enableAudit="false">
<networkBridgeFilterFactory>
<conditionalNetworkBridgeFilterFactory replayWhenNoConsumers="true" />
</networkBridgeFilterFactory>
</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>
<!-- 热备配置：只需要在这里指定服务器地址就好了(有中文会启动失败) 这段注释要删掉 -->
<networkConnectors>
<networkConnector uri="static://(tcp://192.168.5.5:61616,tcp://192.168.5.6:61616)" />
</networkConnectors>
<!--
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&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="amqp" uri="amqp://0.0.0.0:5672?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="stomp" uri="stomp://0.0.0.0:61613?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="mqtt" uri="mqtt://0.0.0.0:1883?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="ws" uri="ws://0.0.0.0:61614?maximumConnections=1000&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"/>
</beans>
<!-- END SNIPPET: example -->
测试：
