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1.Memcached Client简要介绍
Memcached Client目前有3种:
1.Memcached Client for Java 2.SpyMemcached 3.XMemcached
这三种Client一直存在各种争议:
Memcached Client for Java 比 SpyMemcached更稳定、更早、更广泛;SpyMemcached 比 Memcached Client for Java更高效;XMemcached 比 SpyMemcache并发效果更好。
具体可以参考官方性能对比:
Memcached Client for Java: https://github.com/gwhalin/Memcached-Java-Client/wiki/PERFORMANCE
XMemcached: http://xmemcached.googlecode.com/svn/trunk/benchmark/benchmark.html
2.XMemcached特性
高性能;支持完整的memcached文本协议,二进制协议;支持JMX,可以通过MBean调整性能参数、动态添加/移除server、查看统计等;支持客户端统计;支持memcached节点的动态增减;支持memcached分布:余数分布和一致性哈希分布;更多的性能调整选项。
3.XMemcached简单实现
MemcachedClientBuilder是MemcachedClient核心接口,用来控制Client的构建(build()方法)和关闭(shutdown()方法)。 通过build()方法获得 MemcachedClient
然后就可以通过Memcached进行set、get、replace、delete等Memcached操作了!
import static junit.framework.Assert.*;
import java.io.IOException;
import java.util.concurrent.TimeoutException;
import net.rubyeye.xmemcached.MemcachedClient;
import net.rubyeye.xmemcached.MemcachedClientBuilder;
import net.rubyeye.xmemcached.XMemcachedClientBuilder;
import net.rubyeye.xmemcached.command.BinaryCommandFactory;
import net.rubyeye.xmemcached.exception.MemcachedException;
import net.rubyeye.xmemcached.utils.AddrUtil;
import org.junit.Test;
public class MemcachedClientTest {
@Test
public void test() {
MemcachedClientBuilder builder = new XMemcachedClientBuilder(
AddrUtil.getAddresses("192.168.1.110:11211 192.168.1.111:11211"),new int[] { 1, 1});
// 设置连接池大小,即客户端个数
builder.setConnectionPoolSize(50);
// 宕机报警
builder.setFailureMode(true);
// 使用二进制文件
builder.setCommandFactory(new BinaryCommandFactory());
// 使用一致性哈希算法(Consistent Hash Strategy)
builder.setSessionLocator(new KetamaMemcachedSessionLocator());
// 使用序列化传输编码
builder.setTranscoder(new SerializingTranscoder());
// 进行数据压缩,大于1KB时进行压缩
builder.getTranscoder().setCompressionThreshold(1024);
MemcachedClient memcachedClient = null;
try {
memcachedClient = builder.build();
try {
// 设置/获取
memcachedClient.set("aa", 36000, "set/get");
assertEquals("set/get", memcachedClient.get("aa"));
// 替换
memcachedClient.replace("aa", 36000, "replace");
assertEquals("replace", memcachedClient.get("aa"));
// 移除
memcachedClient.delete("aa");
assertNull(memcachedClient.get("aa"));
} catch (TimeoutException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (MemcachedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
if (memcachedClient != null) {
try {
memcachedClient.shutdown();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
4.XMemcached与Spring集成
XMemcached与Spring集成可以参考http://code.google.com/p/xmemcached/wiki/Spring_Integration,这里只说最常用的方法。
memcached.properties做基本配置:
#连接池大小即客户端个数
memcached.connectionPoolSize=50
memcached.failureMode=true
#server1
memcached.server1.host=192.168.1.110
memcached.server1.port=11211
memcached.server1.weight=1
#server2
memcached.server2.host=192.168.1.111
memcached.server2.port=11211
memcached.server2.weight=2
XML配置文件:
<?xml version="1.0" encoding="UTF-8"?>
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!-- http://code.google.com/p/xmemcached/wiki/Spring_Integration -->
<context:property-placeholder location="memcached.properties" />
<bean
id="memcachedClientBuilder"
class="net.rubyeye.xmemcached.XMemcachedClientBuilder"
p:connectionPoolSize="${memcached.connectionPoolSize}"
p:failureMode="${memcached.failureMode}">
<!-- XMemcachedClientBuilder have two arguments.First is server list,and
second is weights array. -->
<constructor-arg>
<list>
<bean class="java.net.InetSocketAddress">
<constructor-arg>
<value>${memcached.server1.host}</value>
</constructor-arg>
<constructor-arg>
<value>${memcached.server1.port}</value>
</constructor-arg>
</bean>
<bean class="java.net.InetSocketAddress">
<constructor-arg>
<value>${memcached.server2.host}</value>
</constructor-arg>
<constructor-arg>
<value>${memcached.server2.port}</value>
</constructor-arg>
</bean>
</list>
</constructor-arg>
<constructor-arg>
<list>
<value>${memcached.server1.weight}</value>
<value>${memcached.server2.weight}</value>
</list>
</constructor-arg>
<property name="commandFactory">
<bean class="net.rubyeye.xmemcached.command.TextCommandFactory" />
</property>
<property name="sessionLocator">
<bean class="net.rubyeye.xmemcached.impl.KetamaMemcachedSessionLocator" />
</property>
<property name="transcoder">
<bean class="net.rubyeye.xmemcached.transcoders.SerializingTranscoder" />
</property>
</bean>
<!-- Use factory bean to build memcached client -->
<bean
id="memcachedClient"
factory-bean="memcachedClientBuilder"
factory-method="build"
destroy-method="shutdown" />
</beans>
这里的 memcachedClientBuilder节点完成 MemcachedClientBuilder,然后通过 memcachedClient节点配置 factory-method,调用 MemcachedClientBuilder的build()方法产生 MemcachedClient,并配置 destroy-method进行关闭。
有了Spring容器支持,我们不需要在代码中进行配置,也不需要重复调用build()跟shutdown()方法,这些操作交给Spring来完成。
import static junit.framework.Assert.*;
import java.util.concurrent.TimeoutException;
import net.rubyeye.xmemcached.MemcachedClient;
import net.rubyeye.xmemcached.exception.MemcachedException;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MemcachedSpringTest {
private ApplicationContext app;
private MemcachedClient memcachedClient;
@Before
public void init() {
app = new ClassPathXmlApplicationContext("applicationContext.xml");
memcachedClient = (MemcachedClient) app.getBean("memcachedClient");
}
@Test
public void test() {
try {
// 设置/获取
memcachedClient.set("aa", 36000, "set/get");
assertEquals("set/get", memcachedClient.get("aa"));
// 替换
memcachedClient.replace("aa", 36000, "replace");
assertEquals("replace", memcachedClient.get("aa"));
// 移除
memcachedClient.delete("aa");
assertNull(memcachedClient.get("aa"));
} catch (TimeoutException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (MemcachedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
5.总结
Memcached的Key,要杜绝使用空格,且长度控制在250个字符。
Memcached的Value,要控制体积,必须小于1MB,必要时进行使用压缩。
失效时间,0为永久有效,最大值不得超过30天(2592000s),否则重新计算可能缓存只有1秒
Memcached仅支持LRU算法,完全适用你的需要。
尽量不要将List这种重体积对象扔到Memcached中,传输、存储都会产生瓶颈。
使用一致性哈希算法实现,提高多个Memcacehd Server利用率。