Hikaril过一段时间就出错，Possibly consider using a shorter maxLifetime value问题

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问题背景：
我用的springboot2.2.，Hikari，，mysql，mp-plus。没有用druid,我不需要监控，就用spring自带的，做数据库连接时候，有段时间不连接，过一会就出错：
HikariPool-1 - Failed to validate connection com.mysql.jdbc.JDBC*********** (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.

***问题尝试解决：***他说的是：Possibly consider using a shorter maxLifetime value.
翻译：可以考虑使用更短的maxLifetime值。

然后我又查了https://github/brettwooldridge/HikariCP
官方解释：maxLifetime
This property controls the maximum lifetime of a connection in the pool. An in-use connection will never be retired, only when it is closed will it then be removed. On a connection-by-connection basis, minor negative attenuation is applied to avoid mass-extinction in the pool. We strongly recommend setting this value, and it should be several seconds shorter than any database or infrastructure imposed connection time limit. A value of 0 indicates no maximum lifetime (infinite lifetime), subject of course to the idleTimeout setting. Default: 1800000 (30 minutes)
翻译：
maxLifetime
此属性控制池中连接的最大生存期。正在使用的连接永远不会退役，只有当它关闭时才会被移除。在逐个连接的基础上，应用了较小的负衰减来避免池中的大规模消光。***我们强烈建议设置此值，它应该比任何数据库或基础设施设置的连接时间限制短几秒。***值0表示没有最大生存期(无限生存期)，当然，这取决于idleTimeout设置。默认值:1 800 000(30分钟)

我的操作：
我最开始是没有任何设置的，然后设置了10 000 也就是10秒，她说最低就要300 000，不然就是默认30分钟，我就设置了30 000可以，60 000可以 80 000不可以，120 000不行，120 000+都不行。
问题貌似是解决了。
官方解释是和我的MYSQL设置有关，但是我查了我的MYSQL：
这个表默认单位是秒，找了很多资料 说是wait_timeout，28800也就是8个小时，我真是日了狗了，Hikaril默认都是30分钟，怎么可能超过8小时？，难道是connect_timeout？10秒，貌似也不是吧？
解决的答案是蒙的，没有什么依据。
路过的大神说说呢？

2020-04-30 00:39:40.706  WARN 21284 --- [nio-9128-exec-6] com.zaxxer.hikari.pool.PoolBase          : HikariPool-1 - Failed to validate connection com.mysql.cj.jdbc.ConnectionImpl@40beab48 (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.
2020-04-30 00:39:40.714 ERROR 21284 --- [nio-9128-exec-6] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30019ms.
### The error may exist in ***************Mapper.java (best guess)
### The error may involve**********************Mapper.selectByMap
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLTransientConnectionException: HikariPool-1 - Connection is not available, request timed out after 30019ms.] with root cause

com.mysql.cj.exceptions.ConnectionIsClosedException: No operations allowed after connection closed.
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)

本文标签： PossiblyHikarilmaxLifetimeshorter