show variables like 'max_execution_time'
使用这个命令查看了，没有设置sql执行超时时间，那么大概率问题就出在阿里的Druid数据库连接池出了问题
尝试着socketTimeout由60000毫秒改成10000毫秒，果然执行了十几秒就超时报错了
socketTimeout: 120000 最后我把这个值调整到120秒才查询出来结果
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure
The last packet successfully received from the server was 10,052 milliseconds ago. The last packet sent successfully to the server was 16,185 milliseconds ago.
