Java Spring中遇到这样的异常？

org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is java.sql.SQLException: com.mchange.v2.c3p0.ComboPooledDataSource [ java.beans.IntrospectionException: java.lang.reflect.InvocationTargetException [numThreadsAwaitingCheckoutDefaultUser] ] has been closed() -- you can no longer use it.
    at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:245)
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:427)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:276)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208)
    at com.sun.proxy.$Proxy83.checkAccountStatus(Unknown Source)
    at com.mc.arkcloud.server.deal.timer.IscsiNetStoreChecker.run(IscsiNetStoreChecker.java:48)
    at java.util.TimerThread.mainLoop(Timer.java:555)
    at java.util.TimerThread.run(Timer.java:505)
Caused by: java.sql.SQLException: com.mchange.v2.c3p0.ComboPooledDataSource [ java.beans.IntrospectionException: java.lang.reflect.InvocationTargetException [numThreadsAwaitingCheckoutDefaultUser] ] has been closed() -- you can no longer use it.
    at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.assertCpds(AbstractPoolBackedDataSource.java:447)
    at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getPoolManager(AbstractPoolBackedDataSource.java:459)
    at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
    at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:204)
    ... 12 more