3. magent编译安装

mkdir magent && cd magent/

wget http://memagent.googlecode.com/files/magent-0.6.tar.gz

tar zxvf magent-0.6.tar.gz
/sbin/ldconfig
sed -i "s#LIBS = -levent#LIBS = -levent -lm#g" Makefile
make
cp magent /usr/bin/magent
cd ../

注解：编译的时候可能报错：

gcc -Wall -g -O2 -I/usr/local/include  -c -o magent.o magent.c
magent.c: In function ‘writev_list’:
magent.c:729: error: ‘SSIZE_MAX’ undeclared (first use in this function)
magent.c:729: error: (Each undeclared identifier is reported only once
magent.c:729: error: for each function it appears in.)
make: *** [magent.o] Error 1

出错原因是在Linux系统上，SSIZE_MAX是定义在limits.h文件中，需要加入“#include <limits.h>”到magent.c中

4. magent命令参数说明：

magent  命令参数说明：
-h this message  
-u uid  
-g gid  
-p port, default is 11211. (0 to disable tcp support)  
-s ip:port, set memcached server ip and port  
-b ip:port, set backup memcached server ip and port  
-l ip, local bind ip address, default is 0.0.0.0  
-n number, set max connections, default is 4096  
-D do not go to background  
-k use ketama key allocation algorithm  
-f file, unix socket path to listen on. default is off  
-i number, max keep alive connections for one memcached server, default is20  
-v verbose

5. 集群实例测试

memcached -m 1 -u root -d -l 127.0.0.1 -p 11211
memcached -m 1 -u root -d -l 127.0.0.1 -p 11212
memcached -m 1 -u root -d -l 127.0.0.1 -p 11213
magent -u root -n 51200 -l 127.0.0.1 -p 12000 -s 127.0.0.1:11211 -s 127.0.0.1:11212 -b 127.0.0.1:11213

注解：

1、分别在11211、11212、11213端口启动3个Memcached进程，在12000端口开启magent代理程序；

2、11211、11212端口为主Memcached，11213端口为备份Memcached；

3、连接上12000的magent，set key1和set key2，根据哈希算法，key1被写入11212和11213端口的Memcached，key2被写入11212和11213端口的Memcached；

4、当11211、11212端口的Memcached死掉，连接到12000端口的magent取数据，数据会从11213端口的Memcached取出；

5、当11211、11212端口的Memcached重启复活，连接到12000端口，magent会从11211或11212端口的Memcached取数据，由于这两台Memcached重启后无数据，因此magent取得的将是空值，尽管11213端口的Memcached还有数据。可采用定时维护服务器，恢复memcached。

6、memcached和magent可以采用混合的方式来实现分布式集群，如下为模型图，

6. 测试流程

[root@rango ~]# telnet 127.0.0.1 12000
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
stats
memcached agent v0.4
matrix 1 -> 127.0.0.1:11211, pool size 0
matrix 2 -> 127.0.0.1:11212, pool size 0
END
set key1 0 0 8
rangochen
STORED
set key2 0 0 8
rangochen
STORED
quit
Connection closed by foreign host.

[root@rango ~]# telnet 127.0.0.1 11211
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
get key1
END
get key2
VALUE key2 0 8
rangochen
END
quit
Connection closed by foreign host.

[root@rango ~]# telnet 127.0.0.1 11212
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
get key1
VALUE key1 0 8
rangochen
END
get key2
END
quit
Connection closed by foreign host.

[root@rango ~]# telnet 127.0.0.1 11213
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
get key1
VALUE key1 0 8
rangochen
END
get key2
VALUE key2 0 8
rangochen
END
quit
Connection closed by foreign host.

模拟11211、11212端口的Memcached死掉
[root@rango ~]# ps -ef | grep memcached
root      6589     1  0 01:25 ?        00:00:00 memcached -m 1 -u root -d -l 127.0.0.1 -p 11211
root      6591     1  0 01:25 ?        00:00:00 memcached -m 1 -u root -d -l 127.0.0.1 -p 11212
root      6593     1  0 01:25 ?        00:00:00 memcached -m 1 -u root -d -l 127.0.0.1 -p 11213
root      6609  6509  0 01:44 pts/0    00:00:00 grep memcached
[root@rango ~]# kill -9 6589
[root@rango ~]# kill -9 6591
[root@rango ~]# telnet 127.0.0.1 12000
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
get key1
VALUE key1 0 8
rangochen
END
get key2
VALUE key2 0 8
rangochen
END
quit
Connection closed by foreign host.

模拟11211、11212端口的Memcached重启复活
[root@rango ~]# memcached -m 1 -u root -d -l 127.0.0.1 -p 11211
[root@rango ~]# memcached -m 1 -u root -d -l 127.0.0.1 -p 11212
[root@rango ~]# telnet 127.0.0.1 12000
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
get key1
END
get key2
END
quit
Connection closed by foreign host.

3.2 java客户端

---

3.2.1 XMemcached是一个基于Java nio的memcached客户端。它线程安全，结构简单，支持所有的memcached文本协议和二进制协议，并且有比较优异的性能表现。它还支持一些高级特性，如JMX、动态增删节点、客户端统计以及nio连接池等。

3.2.2 与同是基于java nio的spymemcached相比来说，XMemcached具有以下特点：
1）API模型是同步，异步的API使用比较繁琐，在memcached协议加入noreply后，异步模型的存在价值就更可疑了；      
2）支持设置memcached的节点权重；      
3）支持动态增删节点，可以通过编程或者JMX；      
4）支持nio连接池，并且允许让用户对网络层面有更多的控制，提供更多的性能优化选项；      
5）支持客户端数据统计；      
6）支持Kestrel，Kestrel是一个scala编写的MQ server。

3.2.3 简单实例
MemcachedClient client;
   try {
    client = new XMemcachedClient("localhost",11211);//默认端口
    // store a value for one hour(synchronously).
    String someObject = "缓存这个一个小时可以吗？";
    client.set("key", 3600, someObject);

// Retrieve a value.(synchronously).
    Object getSomeObject = client.get("key");
    // delete
    client.delete("key");
    System.out.println(getSomeObject.toString());
   } catch (TimeoutException e) {
    e.printStackTrace();
   } catch (InterruptedException e) {
    e.printStackTrace();
   } catch (MemcachedException e) {
    e.printStackTrace();
   } catch (IOException e) {
    e.printStackTrace();
   }
以上代码是没有经过Spring管理的，XMemcachedClient是一个常驻程序。所以可以考虑将它置入到Spring中，配置方式前面已讲过。
使用方式见下：
private MemcachedClient memcachedClient;

public void setMemcachedClient(MemcachedClient memcachedClient) {
   this.memcachedClient = memcachedClient;
}
注入后直接可使用。

4 Memcached监控

---

Memcached的监控方式有多种，对应单机和分布式集群配置：

---

4.1 使用memcache.php来监控memcached

---

这是一种非常方便、快捷的memcached监控方式，下载该文件请戳http://livebookmark.net/memcachephp/memcachephp.zip

下载完后将该文件移动到网页存放目录即可，如/var/www/html/（apache）。在使用之前需要设置登录账户、密码等配置信息：vim memcache.php:

......

define('ADMIN_USERNAME','memcache');    // Admin Username
define('ADMIN_PASSWORD','131415');      // Admin Password

......

$MEMCACHE_SERVERS[] = '192.168.56.1:11211'; // 添加要监控的memcached服务器ip及端口
$MEMCACHE_SERVERS[] = 'mymemcache-server2:11211'; //集群环境下添加多个ip及端口

登录http://ip/memcache.php ，查看相应的监控信息。

4.2 使用Nagios的memcached监控插件来实现

---

1. 可从以下地址下载该插件，请戳 http://cpan.uwinnipeg.ca/cpan/authors/id/Z/ZI/ZIGOROU/Nagios-Plugins-Memcached-0.02.tar.gz

2. 需要保证系统安装有perl环境：

#rpm -q perl

perl-5.10.1-136.el6.i686

#which perl

/usr/bin/perl

3. 编译安装：

#tar zxvf Nagios-Plugins-Memcached-0.02.tar.gz ; cd Nagios-Plugins-Memcached-0.02

#cat README:

......

INSTALLATION

To install this module, run the following commands:

perl Makefile.PL
   make
   make test
   make install

......

#perl Makefile.PL

报错：Can't locate CPAN.pm in @INC (@INC contains: inc /usr/local/lib/perl5 /usr/local/share/perl5 /usr/lib/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib/perl5 /usr/share/perl5 .) at inc/Module/AutoInstall.pm line 635, <STDIN> line 1.

原因是没有安装相应的perl的CPAN模块，解决：yum install perl-CPAN

#make

编译。会下载一些编译所需要的文件。

#make install

安装。从输出信息中可以知道，默认会将check_memcached安装到/usr/bin目录下，将该文件拷贝到Nagios的libexec目录下：cp /usr/bin/check_memcached /usr/local/nagios/libexec/

测试check_memcached:/usr/local/nagios/libexec/check_memcached -h

报以下错误：Base class package "Nagios::Plugin" is empty.
   (Perhaps you need to 'use' the module which defines that package first,
   or make that module available in @INC (@INC contains: /usr/local/nagios/libexec/../lib /usr/local/lib/perl5 /usr/local/share/perl5 /usr/lib/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib/perl5 /usr/share/perl5 .).
at /usr/local/share/perl5/Nagios/Plugins/Memcached.pm line 6
BEGIN failed--compilation aborted at /usr/local/share/perl5/Nagios/Plugins/Memcached.pm line 6.
Compilation failed in require at /usr/local/nagios/libexec/check_memcached line 12.
BEGIN failed--compilation aborted at /usr/local/nagios/libexec/check_memcached line 12.

原因是缺少perl的nagios模块：yum search perl-nagios

Loading mirror speeds from cached hostfile
* epel: mirrors.hust.edu.cn
* rpmforge: mirrors.neusoft.edu.cn
======================== N/S Matched: perl-nagios =========================
perl-Nagios-NSCA.noarch : Nagios::NSCA Perl module
perl-Nagios-Object.noarch : Nagios::Object - Nagios object configuration
                         : parsing
perl-Nagios-Plugin.noarch : Family of perl modules to streamline writing
                         : Nagios
perl-Nagios-Plugin-WWW-Mechanize.noarch : Login to a web page as a user and
                                       : get data as a Nagios plugin

Name and summary matches only, use "search all" for everything.

安装perl-Nagios-Plugin.noarch：yum install perl-Nagios-Plugin.noarch

再执行测试，报以下错误：

Can't locate Carp/Clan.pm in @INC (@INC contains: /usr/local/nagios/libexec/../lib /usr/local/lib/perl5 /usr/local/share/perl5 /usr/lib/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib/perl5 /usr/share/perl5 .) at /usr/local/share/perl5/Nagios/Plugins/Memcached.pm line 8.
BEGIN failed--compilation aborted at /usr/local/share/perl5/Nagios/Plugins/Memcached.pm line 8.
Compilation failed in require at /usr/local/nagios/libexec/check_memcached line 12.
BEGIN failed--compilation aborted at /usr/local/nagios/libexec/check_memcached line 12.

原因是没有安装perl的carp：clan包，安装：yum install perl-Carp-Clan.noarch

最后安装cache：memcached模块：yum install perl-Cache-Memcached.noarch

执行：/usr/local/nagios/libexec/check_memcached -h

check_memcached 0.02 [http://search.cpan.org/dist/Nagios-Plugins-Memcached/bin/check_memcache]

This library is free software, you can redistribute it and/or modify
it under the same terms as Perl itself.

Usage: check_memcached [-H host] [-w warnings] [-c critical] [--size-warnng size-warnng] [--size-critical size-critical] [--hit-warning hit-warning] [--hit-critical hit-critical] [-t timeout] [-v] [-h] [-?] [-V] [--extra-opts section@config_file]

......

4. 配置Nagios：

4.1 修改commands.cfg文件，添加监控命令定义：vim /usr/local/nagios/etc/objects/commands.cfg

#check response time(msec) for memcached
define command {
       command_name    check_memcached_response_11211
       command_line    /usr/local/bin/check_memcached -H 192.168.56.1 -w 300 -c 500
       }
#check cache size ratio(bytes/limit_maxbytes[%]) for memcached
define command {
       command_name    check_memcached_11211
       command_line    $USER1$/check_memcached -H 192.168.56.1:11211 --size-warning 80 --size-critical 90
       }
#check cache hit ratio(get_hits/cmd_get[%]) for memcached
define command {
       command_name    check_memcached_hit

command_line    /usr/local/bin/check_memcached -H 192.168.56.1 --hit-warning 10 --size-critical 5
       }

注解：以上三个命令分别为：监控memcached是否有响应、监控memcached的内存使用比例 、监控memcached的击中率。

4.2 添加主机和服务：vim /usr/local/nagios/etc/objects/memcached.cfg

define host{
       use             linux-server
       host_name       memcache
       alias           Memcache_server
       address         192.168.56.1
       }

define service{
       use             generic-service
       host_name       memcache
       service_description     Memcached_response
       check_command   check_memcached_response_11211
       }

define service{
       use             generic-service
       host_name       memcache
       service_description     Memcached_size
       check_command   check_memcached_11211
       }
define service{
       use     generic-service
       host_name       memcache

service_description     Memcached_hit
       check_command   check_memcached_hit
       }

4.3 将memcached.cfg添加到Nagios主配置文件中：

cfg_file=/usr/local/nagios/etc/objects/memcached.cfg

4.4 检查Nagios配置是否有误：/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

4.5 重启Nagios，并登录Nagios web监控界面查看：

/etc/init.d/nagios restart

登录：http://localhost/nagios

4.3 使用MemAdmin监控管理工具来实现

---

MemAdmin是一款基于 PHP5 & JQuery、 可视化的Memcached管理与监控工具，使用PHP开发，体积小，操作简单。主页请戳http://www.junopen.com/memadmin/