我使用Tomcat Server 8.5.xx创建了一个Web服务器/应用程序。
我使用servlet作为服务器技术。 XML-RPC与用户通信。和MySQL作为数据库。
当我运行应用程序（服务器）时，有时我会出现以下错误：
06-Sep-2017 12:39:06.260 WARNUNG [commons-pool-EvictionTimer] org.apache.tomcat.dbcp.dbcp2.SwallowedExceptionLogger.onSwallowException An internal object pool swallowed an Exception.
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet successfully received from the server was 4.740.870 milliseconds ago. The last packet sent successfully to the server was 0 milliseconds ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:989)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3746)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1873)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1226)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2194)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2225)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2024)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:779)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:389)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
at org.apache.tomcat.dbcp.dbcp2.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:38)
at org.apache.tomcat.dbcp.dbcp2.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:257)
at org.apache.tomcat.dbcp.pool2.impl.GenericObjectPool.create(GenericObjectPool.java:888)
at org.apache.tomcat.dbcp.pool2.impl.GenericObjectPool.ensureIdle(GenericObjectPool.java:952)
at org.apache.tomcat.dbcp.pool2.impl.GenericObjectPool.ensureMinIdle(GenericObjectPool.java:931)
at org.apache.tomcat.dbcp.pool2.impl.BaseGenericObjectPool$Evictor.run(BaseGenericObjectPool.java:1047)
at java.util.TimerThread.mainLoop(Unknown Source)
at java.util.TimerThread.run(Unknown Source)
Caused by: java.net.SocketException: Software caused connection abort: socket write error
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(Unknown Source)
at java.net.SocketOutputStream.write(Unknown Source)
at java.io.BufferedOutputStream.flushBuffer(Unknown Source)
at java.io.BufferedOutputStream.flush(Unknown Source)
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3728)
... 22 more
我可以提供解决问题所需的任何数据。
它可以与数据库一起工作并进行通信，但有时它会挂起然后再出现这个问题然后再次运行。
我猜这个问题来自于MySQL关闭的空闲未使用的连接，但是JDBC没有对此做任何事情并且它试图使用它们。