Spring Download: Communication failure after hours of inactivity with Hibernate, JDBC, and MySQL

Question

I get this error if my Spring boot application is inactive for several hours (e.g. at night):

2015-05-19 09:16:32.666 WARN 20582 --- [http-nio-8080-exec-6] ohengine.jdbc.spi.SqlExceptionHelper : SQL Error: 0, SQLState: 08S01 2015-05-19 09:16:32.668 ERROR 20582 --- [http-nio-8080-exec-6] ohengine.jdbc.spi.SqlExceptionHelper : Communications link failure The last packet successfully received from the server was 29.792.613 milliseconds ago. The last packet sent successfully to the server was 6 milliseconds ago. 

Trying to solve this problem, I read that MySQL has a parameter called wait_timeout set by default to 8 hours (28800 seconds), and after that all my inactive connections are closed, so my Spring Application Download stops working ...

My questions:

• How can I avoid this problem?
• Should I increase the value for such a parameter?
• Are there any disadvantages that increase this value? (It can always be the value reached by my application, if it has been inactive for so long ..: /)
• Is there another solution using Spring Boot (like polling or something like that)?

---

EDIT

There are other similar / useful questions here:

• Hibernate communication error in a Java Servlet application based on Hibernate MySQL
• Spring loses connection with the database and does not restore or restore .
• WARN SqlExceptionHelper: 143 - SQL Error: 0, SQLState: 08S01- SqlExceptionHelper: 144 - Communication Communication Error
• SQL Error: 0, SQLState: 08S01 Communication Communication Error
• https://serverfault.com/questions/89955/unable-to-connect-to-mysql-through-jdbc-connector-through-tomcat-or-externally
• Link Failure Solution with JDBC and MySQL

From the above links, I can conclude that one of the solutions is to add C3p0 as an additional library and set it up correctly to avoid a communication error.

Is this the only solution I have? Isn't there a more integrated solution with Spring / Spring Boot (i.e., without adding an external library)?

Answer 1

I solved the problem as described here: http://blog.netgloo.com/2015/07/09/spring-boot-communications-link-failure-with-mysql-and-hibernate/ by adding these configurations to the application.properties file application.properties :

 spring.datasource.tomcat.testWhileIdle = true spring.datasource.tomcat.timeBetweenEvictionRunsMillis = 60000 spring.datasource.tomcat.validationQuery = SELECT 1