Twemproxy(又称为nutcracker)是一个轻量级的Redis和Memcached代理，主要用来减少对后端缓存服务器的连接数。由Twitter开源出来的缓存服务器集群管理工具，主要用来弥补Redis和Memcached对集群(cluster)管理指出的不足。
Twemproxy是一个快速的单线程代理程序，支持Memcached ASCII协议和更新的Redis协议。
Twemproxy最了不起的地方就在于它能在节点失败的时候卸载它，然后可以在一段时间以后重新尝试（随即）连接，又或者可以严格按照配置文件中写的键与服务器之间对应关系进行连接。
安装部署
现有测试机：192.168.11.51/52/68
先在51和52测试机上安装好libevent和memcached，分别启动两个memcached实例；
然后在68上安装好twemproxy，配置好参数，启动twemproxy实例。
安装和启动memcached实例
详细步骤，请参见之前的博文《Memcached 1.4.22安装和配置》，分别启动如下实例：
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/usr/local/bin/memcached
-d -m 128 -u memcached -l 192.168.11.51 -p 11211 -c 1024 -P
/var/run/memcached/memcached1
.pid
/usr/local/bin/memcached
-d -m 128 -u memcached -l 192.168.11.51 -p 11212 -c 1024 -P
/var/run/memcached/memcached2
.pid
/usr/local/bin/memcached
-d -m 128 -u memcached -l 192.168.11.52 -p 11211 -c 1024 -P
/var/run/memcached/memcached1
.pid
/usr/local/bin/memcached
-d -m 128 -u memcached -l 192.168.11.52 -p 11212 -c 1024 -P
/var/run/memcached/memcached2
.pid
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安装和启动twemproxy实例
1、安装autoconf
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cd
/tmp
wget http:
//ftp
.gnu.org
/gnu/autoconf/autoconf-2
.69.
tar
.gz
tar
zxvf autoconf-2.69.
tar
.gz
cd
autoconf-2.69
.
/configure
--prefix=
/usr/
make
&&
make
install
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2、安装twemproxy
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cd
/tmp
wget https:
//github
.com
/twitter/twemproxy/archive/master
.zip
unzip master.zip -d
/usr/local/
cd
/usr/local
mv
twemproxy-master twemproxy
cd
twemproxy
CFLAGS=
"-ggdb3 -O0"
autoreconf -fvi
.
/configure
--prefix=
/usr/local/twemproxy
--
enable
-debug=log
make
&&
make
install
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3、查看帮助
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[root@test01 twemproxy]
# ./sbin/nutcracker -h
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This is nutcracker-0.4.0
Usage: nutcracker [-?hVdDt] [-v verbosity level] [-o output file]
[-c conf file] [-s stats port] [-a stats addr]
[-i stats interval] [-p pid file] [-m mbuf size]
Options:
-h, --help : this help
-V, --version : show version and exit
-t, --test-conf : test configuration for syntax errors and exit
-d, --daemonize : run as a daemon
-D, --describe-stats : print stats description and exit
-v, --verbose=N : set logging level (default: 5, min: 0, max: 11)
-o, --output=S : set logging file (default: stderr)
-c, --conf-file=S : set configuration file (default: conf/nutcracker.yml)
-s, --stats-port=N : set stats monitoring port (default: 22222)
-a, --stats-addr=S : set stats monitoring ip (default: 0.0.0.0)
-i, --stats-interval=N : set stats aggregation interval in msec (default: 30000 msec)
-p, --pid-file=S : set pid file (default: off)
-m, --mbuf-size=N : set size of mbuf chunk in bytes (default: 16384 bytes)
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4、修改配置文件
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mkdir
/etc/nutcracker
cp
.
/conf/nutcracker
.yml
/etc/nutcracker/
vi
/etc/nutcracker/nutcracker
.yml
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memcached:
listen: 192.168.11.55:22121
hash: fnvla_64
distribution: ketama
timeout: 400
backlog: 1024
preconnect: true
auto_eject_hosts: true
server_retry_timeout: 30000
server_failure_limit: 3
servers:
- 192.168.11.51:11211:1
- 192.168.11.51:11212:1
- 192.168.11.52:11211:1
- 192.168.11.52:11212:1
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参数解析：
listen: 启动twemproxy服务的IP和端口
hash: 指定具体的哈希函数
distribution: 指定具体的哈希算法
preconnect: 一个布尔值，如果该控件的nutcracker前端连接在这个池上的所有服务器进程启动。默认值为假
auto_eject_hosts: 是否在结点无法响应的时候临时摘除结点
server_retry_timeout: 重试的时间（毫秒）
server_failure_limit: 结点故障多少次就算摘除掉
servers: 下面表示所有的memcached节点（IP:端口号:权重）
5、配置以服务启动
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cp
.
/scripts/nutcracker
.init
/etc/init
.d
/nutcracker
chmod
755
/etc/init
.d
/nutcracker
vi
/etc/init
.d
/nutcracker
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1. 新增定义daemo
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daemon="/usr/local/twemproxy/sbin/nutcracker"
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2. 替换所有
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daemon --user ${USER} ${prog} $OPTIONS
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为
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${daemo} $OPTIONS
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chkconfig --add nutcracker
chkconfig --level 35 nutcracker on
chkconfig --list nutcracker
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vi
/etc/profile
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在里面加入：
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export PATH="$PATH:/usr/local/twemproxy/sbin"
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.
/etc/profile
echo
$PATH
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6、测试配置并启动服务
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nutcracker -t -c
/etc/nutcracker/nutcracker
.yml
service nutcracker start
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数据写入测试
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[root@test01 init.d]
# telnet 192.168.11.55 11211
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Trying 192.168.11.55...
Connected to 192.168.11.55.
Escape character is '^]'.
set key1 0 0 1
1
STORED
set key2 0 0 2
22
STORED
set key3 0 0 3
333
STORED
set key4 0 0 4
4444
STORED
set key5 0 0 5
55555
STORED
quit
Connection closed by foreign host.
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[root@test01 ~]
# telnet 192.168.11.51 11211
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Trying 192.168.11.51...
Connected to 192.168.11.51.
Escape character is '^]'.
get key1
END
get key2
END
get key3
END
get key4
END
get key5
END
quit
Connection closed by foreign host.
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[root@test01 ~]
# telnet 192.168.11.51 11212
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Trying 192.168.11.51...
Connected to 192.168.11.51.
Escape character is '^]'.
get key1
END
get key2
END
get key3
END
get key4
END
get key5
END
quit
Connection closed by foreign host.
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[root@test02 ~]
# telnet 192.168.11.52 11211
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Trying 192.168.11.52...
Connected to 192.168.11.52.
Escape character is '^]'.
get key1
END
get key2
END
get key3
END
get key4
END
get key5
END
quit
Connection closed by foreign host.
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[root@test02 ~]
# telnet 192.168.11.52 11212
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Trying 192.168.11.52...
Connected to 192.168.11.52.
Escape character is '^]'.
get key1
VALUE key1 0 1
1
END
get key2
VALUE key2 0 2
22
END
get key3
VALUE key3 0 3
333
END
get key4
VALUE key4 0 4
4444
END
get key5
VALUE key5 0 5
55555
END
quit
Connection closed by foreign host.
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可以看到数据全部从52的11212端口获取到。
现在停掉52的11212端口服务。
继续往代理写数据。
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[root@test03 init.d]
# telnet 192.168.11.55 11211
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Trying 192.168.11.55...
Connected to 192.168.11.55.
Escape character is '^]'.
set username 0 0 6
ryanxu
STORED
set aa 0 0 2
aa
STORED
quit
Connection closed by foreign host.
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[root@test03 init.d]
# telnet 192.168.11.55 11211
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Trying 192.168.11.55...
Connected to 192.168.11.55.
Escape character is '^]'.
get key1
SERVER_ERROR Connection refused
Connection closed by foreign host.
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[root@test03 init.d]
# telnet 192.168.11.55 11211
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Trying 192.168.11.55...
Connected to 192.168.11.55.
Escape character is '^]'.
get key1
SERVER_ERROR Connection refused
Connection closed by foreign host.
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[root@test03 init.d]
# telnet 192.168.11.55 11211
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Trying 192.168.11.55...
Connected to 192.168.11.55.
Escape character is '^]'.
get key1
END
get key2
END
get key3
END
quit
Connection closed by foreign host.
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一台memcached 挂掉后，twemproxy 能够自动摘除。恢复后，twemproxy 能够自动识别、恢复并重新加入到 memcached 组中重新使用。
问题总结
1）.yml配置文件中每个参数值对分隔符”:”后需要有一个空格。
2）不同层次的参数需要缩进区分，最好使用tab键缩进，否则nutcracker进程不能启动。
3）在auto_eject_hosts: true的时候，关闭一个memcached实例后，写入数据还是提示“(error) ERR Connection refused”。这个与server_retry_timeout参数设置太小有关，30000是一个很好的选择。
本文转自UltraSQL51CTO博客，原文链接：http://blog.51cto.com/ultrasql/1639400 ，如需转载请自行联系原作者
