几天前，我遇到了一个非常奇怪的异常，有人无法登录我的应用程序。现在我要重现它...
这是一个例外：
org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin transaction failed:
at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:428)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:372)
at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:417)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:255)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:155)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.data.jpa.repository.support.LockModeRepositoryPostProcessor$LockModePopulatingMethodIntercceptor.invoke(LockModeRepositoryPostProcessor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
at com.sun.proxy.$Proxy82....
....at java.lang.Thread.run(Thread.java:724)
Caused by: javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin transaction failed:
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1377)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1300)
at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:1387)
at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:62)
at org.springframework.orm.jpa.DefaultJpaDialect.beginTransaction(DefaultJpaDialect.java:71)
at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:378) ... 87 more
Caused by: org.hibernate.TransactionException: JDBC begin transaction failed:
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:76)
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.begin(AbstractTransactionImpl.java:160)
at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1392)
at org.hibernate.ejb.TransactionImpl.begin(TransactionImpl.java:59) ... 89 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure The last packet successfully received from the server was 32,971,422 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(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3670)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3559)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4110)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2570)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2731)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2809)
at com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:5333)
at com.mchange.v2.c3p0.impl.NewProxyConnection.setAutoCommit(NewProxyConnection.java:912)
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:72) ... 92 more
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:3119)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3570) ... 100 more
到目前为止我只得到过一次，不知道如何重现。又有数千人登录成功。如果我没记错的话，根本原因是数据库端的一种超时-我不知道是什么，只是一种直觉...因此将报告扩展为上次请求时间和服务器生成报告的时间，但从那以后什么都没有发生。
任何建议它是什么或如何重现？