memcached 集群单点故障解决方案-magent

浅浅的花香味﹌ 2022-06-17 08:57 220阅读 0赞

# memcached 集群单点故障解决方案 #

magent是一款开源的Memcached代理服务器软件，其项目网址为：  
  
　　 http://code.google.com/p/memagent/  
  
　　一、安装步骤：  
　　1、编译安装libevent：

wget  http://monkey.org/~provos/libevent-1.4.9-stable.tar.gz  
tar zxvf libevent-1.4.9-stable.tar.gz  
cd libevent-1.4.9-stable/  
./configure --prefix=/usr  
make && make install  
cd ../

2、编译安装Memcached：

wget  http://danga.com/memcached/dist/memcached-1.2.6.tar.gz  
tar zxvf memcached-1.2.6.tar.gz  
cd memcached-1.2.6/  
./configure --with-libevent=/usr  
make && make install  
cd ../

3、编译安装magent：

mkdir magent  
cd magent/  
wget  http://memagent.googlecode.com/files/magent-0.5.tar.gz  
tar zxvf magent-0.5.tar.gz  
/sbin/ldconfig  
sed -i "s\#LIBS = -levent\#LIBS = -levent -lm\#g" Makefile  
make  
cp magent /usr/bin/magent  
cd ../

--------------------

二、使用实例：

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

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（此问题尚待改进）。

--------------------

三、整个测试流程：

\[root@centos52 ~\]\# 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  
zhangyan  
STORED  
set key2 0 0 8  
zhangyan  
STORED  
quit  
Connection closed by foreign host.  
  
  
\[root@centos52 ~\]\# 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  
zhangyan  
END  
quit  
Connection closed by foreign host.  
  
  
\[root@centos52 ~\]\# 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  
zhangyan  
END  
get key2  
END  
quit  
Connection closed by foreign host.  
  
  
\[root@centos52 ~\]\# 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  
zhangyan  
END  
get key2  
VALUE key2 0 8  
zhangyan  
END  
quit  
Connection closed by foreign host.  
  
  
模拟11211、11212端口的Memcached死掉  
\[root@centos52 ~\]\# 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  
\[root@centos52 ~\]\# kill -9 6589  
\[root@centos52 ~\]\# kill -9 6591  
\[root@centos52 ~\]\# 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  
zhangyan  
END  
get key2  
VALUE key2 0 8  
zhangyan  
END  
quit  
Connection closed by foreign host.  
  
  
模拟11211、11212端口的Memcached重启复活  
\[root@centos52 ~\]\# memcached -m 1 -u root -d -l 127.0.0.1 -p 11211  
\[root@centos52 ~\]\# memcached -m 1 -u root -d -l 127.0.0.1 -p 11212  
\[root@centos52 ~\]\# 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.