Memcached的代理服务器软件：magent使用小记

时间：2022-03-23 08:01:30

　[文章作者：张宴 本文版本：v1.0 最后修改：2009.01.19 转载请注明原文链接：http://blog.s135.com/post/393/ ]

　　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.

 

附用法介绍 ：

magent is a simple but useful proxy program for memcached servers.

It features:

  • keeps connections to memcached servers
  • supports following memcached commands
    1. get gets
    2. delete
    3. incr decr
    4. add set replace prepend append
    5. cas
  • event-driven by using libevent library
  • supports ketama algorithm
  • backup servers farm
  • unix domain socket

Usage:

  
-
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
 
is
 
20


  
-
v verbose

Changelog:

2010/4/14: memcached agent 0.6

  1. add connection keepalive handler
  2. bug fix, more robust, more debug messages

Examples:

  magent 
-
s 
10.1
.
2.1
 
-
s 
10.1
.
2.2
:
11211
 
-
b 
10.1
.
2.3
:
14000
 
-
v

Notes:

  1. current magent's speed is about 80% of memcached's. finding way to speed it up(not good)
  2. adding backup server does no harm to magent's performance. (good)
  3. magent's cpu usage is less than memcached's and has very little memory usage. (good)
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