参数误认为全局参数。
正确的参数初始化设置应该为：
[mysqld]
wait_timeout=30
建议大家今后查询变量的时候不要使用缺省。
查询会话变量：
mysql> show session variables like '%wait%';
+--------------------------+----------+
| Variable_name | Value |
+--------------------------+----------+
| innodb_lock_wait_timeout | 50 |
| innodb_spin_wait_delay | 6 |
| lock_wait_timeout | 31536000 |
| wait_timeout | 28800 |
+--------------------------+----------+
4 rows in set (0.00 sec)
查询全局变量：
mysql> show global variables like '%wait%';
+--------------------------+----------+
| Variable_name | Value |
+--------------------------+----------+
| innodb_lock_wait_timeout | 50 |
| innodb_spin_wait_delay | 6 |
| lock_wait_timeout | 31536000 |
| wait_timeout | 30 |
+--------------------------+----------+
4 rows in set (0.00 sec)