背景

手动判断读/写请求并据此指定需要访问的MySQL服务器，这个时候比较容易出错，而且客户端的业务代码会跟后端服务器的路由选择耦合。选用代理可以比较好地实现读写分离对服务端代码的透明，就像操作一个单机的MySQL数据库一样，读写请求的分离和读请求的负载，就交给了代理。

这里选用amoeba作为代理

基础设施

启动（申请）5台机器，其规划如下：

mysql-1  192.168.1.25  主
mysql-2  192.168.1.26  从
mysql-3  192.168.1.27  从
mysql-4  192.168.1.31  从
amoeba   192.168.1.32  读写分离代理

架构

读写分离代理-2.png

几种读写分离的实现：

  1. code
  2. component/lib
  3. proxy

配置

  1. 下载amoeba： https://sourceforge.net/projects/amoeba/

  2. 传到服务器并 unzip amoeba-mysql-3.0.5-RC.zip 解压

  3. vim amoeba-mysql-3.0.5-RC/conf/dbServers.xml 作如下修改

    <?xml version="1.0" encoding="gbk"?>

<!DOCTYPE amoeba:dbServers SYSTEM "dbserver.dtd">
<amoeba:dbServers xmlns:amoeba="<http://amoeba.meidusa.com/>">

		<!-- 
		     			Each dbServer needs to be configured into a Pool,
			If you need to configure multiple dbServer with load balancing that can be simplified by the following configu
ration:			 add attribute with name virtual = "true" in dbServer, but the configuration does not allow the element with n
ame factoryConfig			 such as 'multiPool' dbServer   
		-->
		
	<dbServer name="abstractServer" abstractive="true">
		<factoryConfig class="com.meidusa.amoeba.mysql.net.MysqlServerConnectionFactory">
			<property name="connectionManager">${defaultManager}</property>
			<property name="sendBufferSize">64</property>
			<property name="receiveBufferSize">128</property>
				
			<!-- mysql port -->
			<property name="port">3306</property>
			
			<!-- mysql schema -->
			<property name="schema">test</property>
			
			<!-- mysql user -->
			<property name="user">root</property>
			
			<property name="password">P@ssw0rd</property>
		</factoryConfig>

		<poolConfig class="com.meidusa.toolkit.common.poolable.PoolableObjectPool">
			<property name="maxActive">500</property>
			<property name="maxIdle">500</property>
			<property name="minIdle">1</property>
			<property name="minEvictableIdleTimeMillis">600000</property>
			<property name="timeBetweenEvictionRunsMillis">600000</property>
			<property name="testOnBorrow">true</property>
			<property name="testOnReturn">true</property>
			<property name="testWhileIdle">true</property>
		</poolConfig>
	</dbServer>

	<dbServer name="writedb"  parent="abstractServer">
		<factoryConfig>
			<!-- mysql ip -->
			<property name="ipAddress">192.168.1.25</property>
		</factoryConfig>
	</dbServer>

<dbServer name="slave0"  parent="abstractServer">
		<factoryConfig>
			<!-- mysql ip -->
			<property name="ipAddress">192.168.1.25</property>
		</factoryConfig>
	</dbServer>
	
	<dbServer name="slave1"  parent="abstractServer">
		<factoryConfig>
			<!-- mysql ip -->
			<property name="ipAddress">192.168.1.26</property>
		</factoryConfig>
	</dbServer>
	<dbServer name="slave2"  parent="abstractServer">
		<factoryConfig>
			<!-- mysql ip -->
			<property name="ipAddress">192.168.1.27</property>
		</factoryConfig>
	</dbServer>
	<dbServer name="slave3"  parent="abstractServer">
		<factoryConfig>
			<!-- mysql ip -->
			<property name="ipAddress">192.168.1.31</property>
		</factoryConfig>
	</dbServer>
	<dbServer name="myslave" virtual="true">
		<poolConfig class="com.meidusa.amoeba.server.MultipleServerPool">
			<!-- Load balancing strategy: 1=ROUNDROBIN , 2=WEIGHTBASED , 3=HA-->
			<property name="loadbalance">1</property>
			
			<!-- Separated by commas,such as: server1,server2,server1 -->
			<property name="poolNames">slave0,slave1,slave2,slave3</property>
		</poolConfig>
	</dbServer>
</amoeba:dbServers>

    其中writedb和slaveX都是自己定义的名字，writedb是主库，slaveX是从库，把他们的IP地址指定好，这里 192.168.1.25 是主库，其余的是从库IP，后面会用到。myslave指的是从库集群，配置了负载策略和从库pool。poolNames 里面写的是各个从库的名字，比如：slave1-slaveN。注：这种配置之下，主库并不承担读请求

  4. vim amoeba-mysql-3.0.5-RC/conf/amoeba.xml

    <?xml version="1.0" encoding="gbk"?>

<!DOCTYPE amoeba:configuration SYSTEM "amoeba.dtd">
<amoeba:configuration xmlns:amoeba="<http://amoeba.meidusa.com/>">

	<proxy>
	
		<!-- service class must implements com.meidusa.amoeba.service.Service -->
		<service name="Amoeba for Mysql" class="com.meidusa.amoeba.mysql.server.MySQLService">
			<!-- port -->
			<property name="port">8066</property>
			
			<!-- bind ipAddress -->
			<!-- 
			     			<property name="ipAddress">127.0.0.1</property>
			 -->
			
			<property name="connectionFactory">
				<bean class="com.meidusa.amoeba.mysql.net.MysqlClientConnectionFactory">
					<property name="sendBufferSize">128</property>
					<property name="receiveBufferSize">64</property>
				</bean>
			</property>
			
			<property name="authenticateProvider">
				<bean class="com.meidusa.amoeba.mysql.server.MysqlClientAuthenticator">
					
					<property name="user">root</property>
					
					<property name="password">P@ssw0rd</property>
					
					<property name="filter">
						<bean class="com.meidusa.toolkit.net.authenticate.server.IPAccessController">
							<property name="ipFile">${amoeba.home}/conf/access_list.conf</property>
						</bean>
					</property>
				</bean>
			</property>
			
		</service>
		
		<runtime class="com.meidusa.amoeba.mysql.context.MysqlRuntimeContext">
			
			<!-- proxy server client process thread size -->
			<property name="executeThreadSize">128</property>
			
			<!-- per connection cache prepared statement size  -->
			<property name="statementCacheSize">500</property>
			
			<!-- default charset -->
			<property name="serverCharset">utf8</property>
			
			<!-- query timeout( default: 60 second , TimeUnit:second) -->
			<property name="queryTimeout">60</property>
		</runtime>
		
	</proxy>
	
	<!-- 
	     		Each ConnectionManager will start as thread
		manager responsible for the Connection IO read , Death Detection
	-->
	<connectionManagerList>
		<connectionManager name="defaultManager" class="com.meidusa.toolkit.net.MultiConnectionManagerWrapper">
			<property name="subManagerClassName">com.meidusa.toolkit.net.AuthingableConnectionManager</property>
		</connectionManager>
	</connectionManagerList>
	
		<!-- default using file loader -->
	<dbServerLoader class="com.meidusa.amoeba.context.DBServerConfigFileLoader">
		<property name="configFile">${amoeba.home}/conf/dbServers.xml</property>
	</dbServerLoader>
	
	<queryRouter class="com.meidusa.amoeba.mysql.parser.MysqlQueryRouter">
		<property name="ruleLoader">
			<bean class="com.meidusa.amoeba.route.TableRuleFileLoader">
				<property name="ruleFile">${amoeba.home}/conf/rule.xml</property>
				<property name="functionFile">${amoeba.home}/conf/ruleFunctionMap.xml</property>
			</bean>
		</property>
		<property name="sqlFunctionFile">${amoeba.home}/conf/functionMap.xml</property>
		<property name="LRUMapSize">1500</property>
		<property name="defaultPool">writedb</property>
		
		<property name="writePool">writedb</property>
		<property name="readPool">myslave</property>
		<property name="needParse">true</property>
	</queryRouter>
</amoeba:configuration>

    这里配置了代理的端口8066，服务的集群主库和从库pool，以及缓存策略，各种bean及其${}属性都不用改

  5. 修改amoeba根目录下的 [jvm.properties](<http://jvm.properties>) 文件，确保其中JVM_OPTIONS中设置的stack空间大于229k：

    JVM_OPTIONS="-server -Xms256m -Xmx1024m -Xss256k -XX:PermSize=16m -XX:MaxPermSize=96m"

  6. 在确保各个MySQL节点都正常运行的情况下，启动amoeba： bin/launcher