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Memcached笔记——（一）安装&常规错误&监控 

一、下载 
1.Libevent 
简单的说就是一个事件触发的网络库，Memcached离不开它。 

wget http://cloud.github.com/downloads/libevent/libevent/libevent-2.0.17-stable.tar.gz

2.Memcached 
今天的主角 

wget http://memcached.googlecode.com/files/memcached-1.4.13.tar.gz

二、安装 
1.Libevent 
解压缩 

tar zxvf libevent-2.0.17-stable.tar.gz

编译、安装 

./configure --prefix=/usr && make && make install

这里一定要注意指定--prefix，后面配置memcached的时候就有必要用到。 
2.Memcached 
解压 

tar zxvf memcached-1.4.13.tar.gz

编译、安装 

./configure --with-libevent=/usr/lib && make && make install

这里一定要指定libevent的路径，否则启动的时候就有找不到libevent的so文件的错误！ 
启动 

memcached -d -m 512 -p 11211 -u root -c 256 -P /var/run/memcached.pid

参数 

引用

-p <num>      TCP port number to listen on (default: 11211) 
-U <num>      UDP port number to listen on (default: 11211, 0 is off) 
-l <addr>     interface to listen on (default: INADDR_ANY, all addresses) 
              <addr> may be specified as host:port. If you don't specify 
              a port number, the value you specified with -p or -U is 
              used. You may specify multiple addresses separated by comma 
              or by using -l multiple times 
-d            run as a daemon 
-u <username> assume identity of <username> (only when run as root) 
-m <num>      max memory to use for items in megabytes (default: 64 MB) 
-M            return error on memory exhausted (rather than removing items) 
-c <num>      max simultaneous connections (default: 1024) 
-v            verbose (print errors/warnings while in event loop) 
-P <file>     save PID in <file>, only used with -d option 

要关掉memcached 

kill -9 `cat /var/run/memcached.pid`

是否正常？Telnet上去看看 

telnet xxx.xxx.xxx.xxx 11211

然后输入

stats

接着就能看到： 

引用

STAT pid 3021 
STAT uptime 3621 
STAT time 1331261509 
STAT version 1.4.13 
STAT libevent 2.0.17-stable 
STAT pointer_size 64 
STAT rusage_user 0.000000 
STAT rusage_system 0.000999 
STAT curr_connections 6 
STAT total_connections 7 
STAT connection_structures 7 
STAT reserved_fds 20 
STAT cmd_get 0 
STAT cmd_set 0 
STAT cmd_flush 0 
STAT cmd_touch 0 
STAT get_hits 0 
STAT get_misses 0 
STAT delete_misses 0 
STAT delete_hits 0 
STAT incr_misses 0 
STAT incr_hits 0 
STAT decr_misses 0 
STAT decr_hits 0 
STAT cas_misses 0 
STAT cas_hits 0 
STAT cas_badval 0 
STAT touch_hits 0 
STAT touch_misses 0 
STAT auth_cmds 0 
STAT auth_errors 0 
STAT bytes_read 72 
STAT bytes_written 1038 
STAT limit_maxbytes 52428800 
STAT accepting_conns 1 
STAT listen_disabled_num 0 
STAT threads 4 
STAT conn_yields 0 
STAT hash_power_level 16 
STAT hash_bytes 524288 
STAT hash_is_expanding 0 
STAT expired_unfetched 0 
STAT evicted_unfetched 0 
STAT bytes 0 
STAT curr_items 0 
STAT total_items 0 
STAT evictions 0 
STAT reclaimed 0 
END 

上面状况说明Memcached服务正常。 
还可以试试get、set、delete、replace 

引用

set foo 0 0 3     （保存命令） 
bar               （数据） 
STORED            （结果） 
get foo           （取得命令） 
VALUE foo 0 3     （数据） 
bar               （数据）

输入

quit

退出。 

三、系统服务 
参照Nginx的系统服务，自己写了一个Memcached的系统服务脚本。 
先构建/etc/init.d/memcahed这个文件，然后赋予其可执行权限： 

touch /etc/init.d/memcached
chmod +x /etc/init.d/memcached

memcached脚本如下： 

#!/bin/bash
# v.0.0.1
# create by snowolf at 2012.5.25
#
# memcached  - This shell script takes care of starting and stopping memcached.
#
# chkconfig: - 90 10
# description: Memcache provides fast memory based storage.
# processname: memcached

memcached_path="/usr/local/bin/memcached"
memcached_pid="/var/run/memcached.pid"
memcached_memory="1024"

# Source function library.
. /etc/rc.d/init.d/functions

[ -x $memcached_path ] || exit 0

RETVAL=0
prog="memcached"

# Start daemons.
start() {
    if [ -e $memcached_pid -a ! -z $memcached_pid ];then
        echo $prog" already running...."
        exit 1
    fi

    echo -n $"Starting $prog "
    # Single instance for all caches
    $memcached_path -m $memcached_memory -l 0.0.0.0 -p 11211 -u root -d -P $memcached_pid
    RETVAL=$?
    [ $RETVAL -eq 0 ] && {
        touch /var/lock/subsys/$prog
        success $"$prog"
    }
    echo
    return $RETVAL
}


# Stop daemons.
stop() {
    echo -n $"Stopping $prog "
    killproc -d 10 $memcached_path
    echo
    [ $RETVAL = 0 ] && rm -f $memcached_pid /var/lock/subsys/$prog

    RETVAL=$?
    return $RETVAL
}

# See how we were called.
case "$1" in
        start)
            start
            ;;
        stop)
            stop
            ;;
        status)
            status $prog
            RETVAL=$?
            ;;
        restart)
            stop
            start
            ;;
        *)
            echo $"Usage: $0 {start|stop|status|restart}"
            exit 1
esac
exit $RETVAL

注意这几行配置，请根据实际情况配置memcached执行文件路径，以及Memcached使用内存大小： 

引用

memcached_path="/usr/local/bin/memcached" 
memcached_memory="1024"

追加为系统服务： 

chkconfig --add memcached
chkconfig memcached on

然后就可以通过service memcached start|stop|status|restart控制memcached了！ 

四、常规错误 
一开始没有指定libevent路径安装memcached的时候，启动memcached就报这个错误： 

引用

memcached: error while loading shared libraries: libevent-2.0.so.5: cannot open shared object file: No such file or directory 

其实这个文件就在/usr/lib下。错就错在Linux是64bit系统，如果没有指定libevent路径，memcached就会去/usr/lib64下去找。 
找到这个文件 

whereis libevent-2.0.so.5

 

引用

libevent-2.0.so: /usr/lib/libevent-2.0.so.5

 

ldd /usr/local/bin/memcached

提示找不到libevent-2.0.so.5 

引用

        linux-vdso.so.1 =>  (0x00007fff41dfd000) 
        libevent-2.0.so.5 => not found 
        librt.so.1 => /lib64/librt.so.1 (0x0000003c94a00000) 
        libpthread.so.0 => /lib64/libpthread.so.0 (0x0000003c93a00000) 
        libc.so.6 => /lib64/libc.so.6 (0x0000003c92e00000) 
        /lib64/ld-linux-x86-64.so.2 (0x0000003c92a00000)

定位 

LD_DEBUG=libs /usr/local/bin/memcached -v

 

引用

     19905:     find library=libevent-2.0.so.5 [0]; searching 
     19905:      search path=/usr/lib/lib/tls/x86_64:/usr/lib/lib/tls:/usr/lib/lib/x86_64:/usr/lib/lib          (RPATH from file /usr/local/bin/memcached) 
     19905:       trying file=/usr/lib/lib/tls/x86_64/libevent-2.0.so.5 
     19905:       trying file=/usr/lib/lib/tls/libevent-2.0.so.5 
     19905:       trying file=/usr/lib/lib/x86_64/libevent-2.0.so.5 
     19905:       trying file=/usr/lib/lib/libevent-2.0.so.5 
     19905:      search cache=/etc/ld.so.cache 
     19905:      search path=/lib64/tls/x86_64:/lib64/tls:/lib64/x86_64:/lib64:/usr/lib64/tls/x86_64:/usr/lib64/tls:/usr/lib64/x86_64:/usr/lib64            (system search path) 
     19905:       trying file=/lib64/tls/x86_64/libevent-2.0.so.5 
     19905:       trying file=/lib64/tls/libevent-2.0.so.5 
     19905:       trying file=/lib64/x86_64/libevent-2.0.so.5 
     19905:       trying file=/lib64/libevent-2.0.so.5 
     19905:       trying file=/usr/lib64/tls/x86_64/libevent-2.0.so.5 
     19905:       trying file=/usr/lib64/tls/libevent-2.0.so.5 
     19905:       trying file=/usr/lib64/x86_64/libevent-2.0.so.5 
     19905:       trying file=/usr/lib64/libevent-2.0.so.5 
     19905: 
/usr/local/bin/memcached: error while loading shared libraries: libevent-2.0.so.5: cannot open shared object file: No such file or directory 

注意这句： 

引用

19905: trying file=/usr/lib64/libevent-2.0.so.5

做个软连接 

ln -s /usr/lib/libevent-2.0.so.5 /usr/lib64/libevent-2.0.so.5

再试试： 

ldd /usr/local/bin/memcached

这回找到了！ 

引用

        linux-vdso.so.1 =>  (0x00007fffffef6000) 
        libevent-2.0.so.5 => /usr/lib64/libevent-2.0.so.5 (0x00002b5608a26000) 
        librt.so.1 => /lib64/librt.so.1 (0x0000003c94a00000) 
        libpthread.so.0 => /lib64/libpthread.so.0 (0x0000003c93a00000) 
        libc.so.6 => /lib64/libc.so.6 (0x0000003c92e00000) 
        /lib64/ld-linux-x86-64.so.2 (0x0000003c92a00000)

五、监控 
可以在服务器上配置一个PHP页面来监测Memcached的情况， 
配置也比较简单，主要包括账户配置，以及Memcached Server地址配置。 

define('ADMIN_USERNAME','memcache');    // Admin Username
define('ADMIN_PASSWORD','password');    // Admin Password
define('DATE_FORMAT','Y/m/d H:i:s');
define('GRAPH_SIZE',200);
define('MAX_ITEM_DUMP',50);

$MEMCACHE_SERVERS[] = 'mymemcache-server1:11211'; // add more as an array
$MEMCACHE_SERVERS[] = 'mymemcache-server2:11211'; // add more as an array

如果不方便搭建PHP服务，可以使用Perl脚本memcache-top 
修改@default_instances或使用--instances参数： 

perl memcache-top-v0.6 --instances 10.11.155.26 10.11.155.41

 

 

 

 

Memcached笔记——（二）XMemcached&Spring集成 

 

一、Memcached Client简要介绍 
Memcached Client目前有3种： 

• Memcached Client for Java
• SpyMemcached
• 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。

用数据来说话，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 

二、XMemcached特性 
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。

此外，XMemcached更容易与Spring集成。而且，属于中国原创！  

三、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）。 
XMemcachedClientBuilder一般通过构造方法配置地址列表，通常还要配置权重，代码如下： 

public XMemcachedClientBuilder(List<InetSocketAddress> addressList) {
    if (addressList != null) {
        for (InetSocketAddress addr : addressList) {
            this.addressMap.put(addr, null);
        }
    }
}

public XMemcachedClientBuilder(List<InetSocketAddress> addressList,
        int[] weights) {
    if (addressList != null) {
        for (InetSocketAddress addr : addressList) {
            this.addressMap.put(addr, null);
        }
    }
    this.weights = weights;
}

不过这哥们如果用this()可以省点代码， 还有给加点注释吧！ 
此外，还需要设置连接池大小，使用二进制协议/文本协议等。 
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！ 
上代码： 

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("10.11.155.26:11211 10.11.155.41:11211 10.10.76.31:11211 10.10.76.35:11211"),
                new int[] { 1, 1, 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());

        MemcachedClient memcachedClient = null;
        try {
            memcachedClient = builder.build();
            try {
                // 设置/获取
                memcachedClient.set("zlex", 36000, "set/get");
                assertEquals("set/get", memcachedClient.get("zlex"));

                // 替换
                memcachedClient.replace("zlex", 36000, "replace");
                assertEquals("replace", memcachedClient.get("zlex"));

                // 移除
                memcachedClient.delete("zlex");
                assertNull(memcachedClient.get("zlex"));
            } 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();
                }
            }
        }
    }
}

四、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=10.11.155.26
memcached.server1.port=11211
memcached.server1.weight=4
#server2
memcached.server2.host=10.11.155.41
memcached.server2.port=11211
memcached.server2.weight=3
#server3
memcached.server3.host=10.10.76.31
memcached.server3.port=11211
memcached.server3.weight=2
#server4
memcached.server4.host=10.10.76.35
memcached.server4.port=11211
memcached.server4.weight=1

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>
                <bean class="java.net.InetSocketAddress">
                    <constructor-arg>
                        <value>${memcached.server3.host}</value>
                    </constructor-arg>
                    <constructor-arg>
                        <value>${memcached.server3.port}</value>
                    </constructor-arg>
                </bean>
                <bean class="java.net.InetSocketAddress">
                    <constructor-arg>
                        <value>${memcached.server4.host}</value>
                    </constructor-arg>
                    <constructor-arg>
                        <value>${memcached.server4.port}</value>
                    </constructor-arg>
                </bean>
            </list>
        </constructor-arg>
        <constructor-arg>
            <list>
                <value>${memcached.server1.weight}</value>
                <value>${memcached.server2.weight}</value>
                <value>${memcached.server3.weight}</value>
                <value>${memcached.server4.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。 
不过我还是疑惑，这里的异常由谁来处理？Spring容器吗？ 或者需要另一个代理Bean包装一下？ 

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。 
代码如下： 

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("zlex", 36000, "set/get");
            assertEquals("set/get", memcachedClient.get("zlex"));

            // 替换
            memcachedClient.replace("zlex", 36000, "replace");
            assertEquals("replace", memcachedClient.get("zlex"));

            // 移除
            memcachedClient.delete("zlex");
            assertNull(memcachedClient.get("zlex"));
        } 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();
        }
    }
}