mysql无法正常查询

现象：

• mysql服务器本地连接查询没有问题
• 其他服务器连接mysql服务进行查询没有问题
• 公司内部连接到mysql服务无法正常进行查询
  • 第一次查询的时候无法查询，第二次查询则成功，第三次查询又失败，第四次则又成功，如此循环,如下：

mysql> show variables like 'max_allowed_packet';
ERROR 2013 (HY000): Lost connection to MySQL server during query
mysql> show variables like 'max_allowed_packet';
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    4325
Current database: *** NONE ***

+--------------------+---------+
| Variable_name      | Value   |
+--------------------+---------+
| max_allowed_packet | 4194304 |
+--------------------+---------+
1 row in set (0.07 sec)

mysql> 

解决办法：

set global innodb_lock_wait_timeout=500;

结果：

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| byex_db_cg         |
+--------------------+
2 rows in set (0.01 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| byex_db_cg         |
+--------------------+
2 rows in set (0.01 sec)