**
mysql-proxy
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MySQL Proxy有一项强大功能是实现“读写分离”，基本原理是让主数据库处理写方面事务，让从库处理SELECT查询。
Amoeba for MySQL是一款优秀的中间件软件，同样可以实现读写分离，负载均衡等功能，并且稳定性也高于MySQL Proxy，有兴趣的可以测试一下。
环境描述：
操作系统：CentOS6.5_x64
主服务器Master：172.25.254.1
从服务器Slave：172.25.254.2
调度服务器MySQL-Proxy：172.25.254.1
proxy安装及配置
proxy安装需要lua
官网下载即可
http://www.lua.org/download.html
下载后 make make install 即可
安装proxy
http://mirrors.sohu.com/mysql/MySQL-Proxy/
下载后
tar zxvf mysql-proxy-0.8.4-linux-glibc2.3-x86-64bit.tar.gz
mv mysql-proxy-0.8.4-linux-glibc2.3-x86-64bit /usr/local/mysql_proxy
cd /usr/local/mysql_proxy/
mkdir scripts
cp share/doc/mysql-proxy/rw-splitting.lua scripts/
vim scripts/rw-splitting.lua
if not proxy.global.config.rwsplit then
proxy.global.config.rwsplit = {
min_idle_connections = 1, #默认4 改为1，表示最小链接数只有超过1时才会进行读写分离
max_idle_connections = 1, #默认8
is_debug = false
}
endproxy 使用信息
[root@server1 mysql-proxy]# bin/mysql-proxy --help-proxy
Usage:
mysql-proxy [OPTION...] - MySQL Proxy
proxy-module
-P, --proxy-address=<host:port> listening address:port of the proxy-server (default: :4040)
-r, --proxy-read-only-backend-addresses=<host:port> address:port of the remote slave-server (default: not set)
-b, --proxy-backend-addresses=<host:port> address:port of the remote backend-servers (default: 127.0.0.1:3306)
--proxy-skip-profiling disables profiling of queries (default: enabled)
--proxy-fix-bug-25371 fix bug #25371 (mysqld > 5.1.12) for older libmysql versions
-s, --proxy-lua-script=<file> filename of the lua script (default: not set)
--no-proxy don't start the proxy-module (default: enabled)
--proxy-pool-no-change-user don't use CHANGE_USER to reset the connection coming from the pool (default: enabled)
--proxy-connect-timeout connect timeout in seconds (default: 2.0 seconds)
--proxy-read-timeout read timeout in seconds (default: 8 hours)
--proxy-write-timeout write timeout in seconds (default: 8 hours)
proxy 管理脚本
#!/bin/sh
export LUA_PATH=/usr/local/share/mysql-proxy/?.lua
mode=$1
if [ -z "$mode" ] ; then
mode="start"
fi
case $mode in
'start')
mysql-proxy --daemon \
--admin-address=:4401 \
--proxy-address=:3307 \
--proxy-backend-addresses=:3306 \
--proxy-read-only-backend-addresses=172.25.254.2:3306 \
--proxy-read-only-backend-addresses=172.25.254.3:3306 \
--proxy-lua-script=/usr/local/share/mysql-proxy/rw-splitting.lua
;;
'stop')
killall mysql-proxy
;;
'restart')
if $0 stop ; then
$0 start
else
echo "retart failed!!!"
exit 1
fi
;;
esac
exit 0
--daemon 采用daemon方式启动
--admin-address=:4401 指定mysql proxy的管理端口，在这里，表示本机的4401端口
--proxy-address=:3307 指定mysql proxy的监听端口，也可以用 127.0.0.1:3307 表示
--proxy-backend-addresses=:3306 指定mysql主机的端口
--proxy-read-only-backend-addresses=192.168.1.1:3306 指定只读的mysql主机端口
--proxy-read-only-backend-addresses=192.168.1.2:3306 指定另一个只读的mysql主机端口
--proxy-lua-script=/usr/local/share/mysql-proxy/rw-splitting.lua 指定lua脚本，在这里，使用的是rw-splitting脚本，用于读写分离**
测试
**
[root@server1 mysql-proxy]# mysql -h127.0.0.1 -uroot -pHh~802119323
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 14
Server version: 5.7.17-log MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show processlist;
+----+------+--------------------+------+-------------+------+---------------------------------------------------------------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+--------------------+------+-------------+------+---------------------------------------------------------------+------------------+
| 8 | bobo | 172.25.254.2:55477 | NULL | Binlog Dump | 8532 | Master has sent all binlog to slave; waiting for more updates | NULL |
| 14 | root | localhost:59434 | NULL | Query | 0 | starting | show processlist |
+----+------+--------------------+------+-------------+------+---------------------------------------------------------------+------------------+
2 rows in set (0.00 sec)
mysql>
[root@server5 mysql-proxy]# cat logs/mysql-proxy.log
2018-08-14 10:14:45: (message) chassis-unix-daemon.c:136: [angel] we try to keep PID=1142 alive
2018-08-14 10:14:45: (debug) chassis-unix-daemon.c:157: waiting for 1142
2018-08-14 10:14:45: (debug) chassis-unix-daemon.c:121: we are the child: 1142
2018-08-14 10:14:45: (critical) plugin proxy 0.8.5 started
2018-08-14 10:14:45: (debug) max open file-descriptors = 1024
2018-08-14 10:14:45: (message) proxy listening on port 0.0.0.0:3306
2018-08-14 10:14:45: (message) added read/write backend: 172.25.15.11:3306
2018-08-14 10:14:45: (message) added read-only backend: 172.25.15.12:3306
2018-08-14 10:14:45: (debug) now running as user: root (0/0)
根据配置文件 打开三台物理机链接proxy端
根据配置可知 只有两台及以下的虚拟机在链接proxy端时，只会链接至master端，在大于两台时，开始读写分离，通过proxy端的losf软件来查看端口用以测试
如下 在第三次链接时指向了slave端，用以查看数据，在写入时，proxy有将数据写入master，达到读写分离。
[root@server5 mysql-proxy]# lsof -i:3306
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mysql-pro 1189 root 10u IPv4 10121 0t0 TCP *:mysql (LISTEN)
mysql-pro 1189 root 11u IPv4 10192 0t0 TCP 172.25.15.15:mysql->172.25.15.250:33792 (ESTABLISHED)
mysql-pro 1189 root 12u IPv4 10193 0t0 TCP 172.25.15.15:57490->172.25.15.11:mysql (ESTABLISHED)
mysql-pro 1189 root 13u IPv4 10194 0t0 TCP 172.25.15.15:mysql->172.25.15.250:33794 (ESTABLISHED)
mysql-pro 1189 root 14u IPv4 10195 0t0 TCP 172.25.15.15:57491->172.25.15.11:mysql (ESTABLISHED)
mysql-pro 1189 root 15u IPv4 10196 0t0 TCP 172.25.15.15:mysql->172.25.15.250:33796 (ESTABLISHED)
mysql-pro 1189 root 16u IPv4 10197 0t0 TCP 172.25.15.15:39735->172.25.15.12:mysql (ESTABLISHED)
测试写入时，注意在第三台打开的主机上链接数据库写入，因为此时proxy将用户指向slave，（没有读写分离时slave无法写入数据，但在proxy调度下可以写入数据）。
客户端
[kiosk@foundation15 ~]$ mysql -h 172.25.15.15 -u root -pHh~802119323
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.7.17-log MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MySQL [(none)]> use westos
Database changed
MySQL [westos]> select * from userlist;
+----------+--------+
| username | passwd |
+----------+--------+
| user1 | 123 |
| user2 | 213 |
+----------+--------+
2 rows in set (0.00 sec)
MySQL [westos]> insert into userlist values('user3','321');
Query OK, 1 row affected (0.03 sec)
MySQL [westos]>
master端
mysql> use westos
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select * from userlist;
+----------+--------+
| username | passwd |
+----------+--------+
| user1 | 123 |
| user2 | 213 |
| user3 | 321 |
+----------+--------+
3 rows in set (0.00 sec)
以上测试完成
proxy的详细运作过程可以通过tcpdump -i eth0来查看