Communications link failure during commit(). Transaction resolution unknown.

JAVA WEB程序运行一段时间后出现以下错误，遍寻之后得到以下解决方案，这个方案并不是万能的，不要一味套用，切记。

原因分析：这个问题出现的原因大部分归结于事务超时，那我们可以增大超时等待的时间，或者从程序角度分拆事务粒度，不要过长时间的执行一个事务。

[com.alibaba.druid.util.JdbcUtils] close connection error
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Communications link failure during rollback(). Transaction resolution unknown.
    at sun.reflect.GeneratedConstructorAccessor30.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
    at com.mysql.jdbc.Util.getInstance(Util.java:387)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:917)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:896)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:885)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
    at com.mysql.jdbc.ConnectionImpl.rollback(ConnectionImpl.java:4602)
    at com.mysql.jdbc.ConnectionImpl.realClose(ConnectionImpl.java:4233)
    at com.mysql.jdbc.ConnectionImpl.close(ConnectionImpl.java:1531)
    at com.alibaba.druid.filter.FilterChainImpl.connection_close(FilterChainImpl.java:169)
    at com.alibaba.druid.filter.stat.StatFilter.connection_close(StatFilter.java:254)
    at com.alibaba.druid.filter.FilterChainImpl.connection_close(FilterChainImpl.java:165)
    at com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl.close(ConnectionProxyImpl.java:115)
    at com.alibaba.druid.util.JdbcUtils.close(JdbcUtils.java:83)
    at com.alibaba.druid.pool.DruidDataSource.shrink(DruidDataSource.java:2307)
    at com.alibaba.druid.pool.DruidDataSource$DestroyTask.run(DruidDataSource.java:2094)
    at com.alibaba.druid.pool.DruidDataSource$DestroyConnectionThread.run(DruidDataSource.java:2081)

解决方案：修改全局wait_timeout值

1. 借用Navicat工具在查询命令窗口进行修改
2. 后台登录mysql管理控制台进行修改

• mysql -uroot -p 先进入到MYSQL数据库
• mysql> show global variables like '%time%' ;
• SET GLOBAL wait_timeout = 288000;