Memcached集群 Magent软件介绍
magent是一款开源的memcached代理服务器软件
地址: http://code.google.com/p/memagent/
安装magent到/usr/local/下
cd /usr/local
mkdir magent
cd magent/
wgethttp://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
magent命令参数:
-hthis message
-u uid
-g gid
-p port, default is 11211. (0 to disable tcpsupport)
-s ip:port, set memcached server ip and port
-b ip:port, set backup memcached server ip andport
-l ip, local bind ip address, default is 0.0.0.0
-n number, set max connections, default is 4096
-D don't go to background
-k use ketama key allocation algorithm
-f file, unix socket path to listen on. defaultis off
-i number, max keep alive connections for onememcached server, default is 20
-v verbose
启动magent服务
magent -u root -n 4096 -l 127.0.0.1 -p12000 -s127.0.0.1:8086 -s 127.0.0.2:8086 -b 127.0.0.1:11213 magent的hash算法
magent采用的是:Consistent Hashing原理,Consistent Hashing如下所示:首先求出memcached服务器(节点)的哈希值,并将其配置到0~232的圆(continuum)上。 然后用同样的方法求出存储数据的键的哈希值,并映射到圆上。 然后从数据映射到的位置开始顺时针查找,将数据保存到找到的第一个服务器上。如果超过232仍然找不到服务器,就会保存到第一台memcached服务器上。
从上图的状态中添加一台memcached服务器。余数分布式算法由于保存键的服务器会发生巨大变化而影响缓存的命中率,但Consistent Hashing中,只有在continuum上增加服务器的地点逆时针方向的第一台服务器上的键会受到影响。
wget http://monkey.org/~provos/libevent-1.4.13-stable.tar.gz
tar -xzvf libevent-1.4.13-stable.tar.gz
cd libevent-1.4.13-stable
./configure --prefix=/usr/local/libevent
make
make install
2、安装Memcached:
wget http://memcached.googlecode.com/files/memcached-1.4.4.tar.gz
tar -xzvf memcached-1.4.4.tar.gz
cd memcached-1.4.4
./configure --prefix=/usr/local/memcached --with-libevent=/usr/local/libevent
make
make install
ln -s /usr/local/libevent/lib/libevent-1.4.so.2 /usr/lib/
3、编译安装magent:
mkdir magent
cp magent-0.5.tar.gz magent
cd magent
tar -xzvf magent-0.5.tar.gz
/sbin/ldconfig
sed -i "s#LIBS = -levent#LIBS = -levent -lm#g" Makefile
vi magent.c 添加
#include
make
# telnet 192.168.1.219 12000
Trying 1192.168.1.219...
Connected to 192.168.1。219.
Escape character is '^]'.
stats
memcached agent v0.4
matrix 1 -> 192.168.1.219:11211, pool size 0
matrix 2 -> 192.168.1.219:11212, pool size 0
END
set key1 0 0 5
reesun
STORED
set key2 0 0 6
reesun1
STORED
quit
Connection closed by foreign host.
# telnet 192.168.1.219 11211
Trying 192.168.1.219...
Connected to 192.168.1.219.
Escape character is '^]'.
get key1
END
get key2
VALUE key2 0 6
reesun1
END
quit
Connection closed by foreign host.
# telnet 192.168.1.219 11212
Trying 192.168.1.219...
Connected to 1192.168.1.219.
Escape character is '^]'.
get key1
VALUE key1 0 5
reesun
END
get key2
END
quit
Connection closed by foreign host.
# telnet 192.168.1.219 11213
Trying 192.168.1.219...
Connected to 1192.168.1.219.
Escape character is '^]'.
get key1
VALUE key1 0 5
reesun
END
get key2
VALUE key2 0 6
reesun1
END
quit
Connection closed by foreign host.