异常-ERROR yarn.ApplicationMaster: User class threw exception: java.sql.SQLException: Communications link failure

1 详细异常信息

ERROR yarn.ApplicationMaster: User class threw exception: java.sql.SQLException: Communications link failure
The last packet successfully received from the server was 18,973 milliseconds ago.  The last packet sent successfully to the server was 3 milliseconds ago. Query: select user_register_analyse_id as userRegisterAnalyseId,day_time as dayTime,city_code as cityCode,city,city_province as cityProvince,province,total_user_register_count as totalUserRegisterCount,day_user_register_count as dayUserRegisterCount,first_order_user_count as firstOrderUserCount,day_user_register_ordered_conversion_rate as dayUserRegisterOrderedConversionRate from t_user_register_analyse where day_time = ? and city_code = ?  limit 1 Parameters: [2019-09-01 00:00:00, 130900]
java.sql.SQLException: Communications link failure

　　

2 检查一下自己的msyql连接是否关闭

解决方案：

　　第一步，先设置下mysql连接的过期时间，让mysql会自动释放连接

　　　　set  global wait_timeout=30

　　　　set  global interactive_timeout=30

　　　　或者 修改my.cnf 重启mysql

　　　　[mysqld]
　　　　wait_timeout=30
　　　　interactive_timeout=30

　 第二步，代码中手动关闭连接，根据自己用的代码api，自己检查下，是否把执行完sql后，关闭资源或者将连接还给线程池。