mysql> show global variables like 'wait_timeout';
其默认值为8小时 28800
mysql的一个connection空闲时间超过8小时，mysql会自动断开该连接。

1.修改配置
vi /etc/my.cnf

[mysqld]
wait_timeout=10

# /etc/init.d/mysql restart

2.直接用sql命令行修改
mysql> set global wait_timeout=10;
mysql> show global variables like 'wait_timeout';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| wait_timeout | 10 |
+----------------------------+-------+


show variables like '%time%';


timeBetweenEvictionRunsMillis = 20000
#dbcp每2000秒进行一次connection的检
minEvictableIdleTimeMillis = 28700
#每次检验中将超过28700秒处于空闲的connection断开