I am getting this exception after all my functional task is completed

When two process are running in parallel

1)I am closing session after each DML operation in each process

2)I am shutting down the session factory after every process

main [2014-06-17 22:15:17,578] [OUT] (HibernateUtil.java:727) Inside Hibernateutil.shutdown()
org.hibernate.exception.GenericJDBCException: Could not open connection
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:52)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:304)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:169)
at org.hibernate.engine.jdbc.internal.proxy.ConnectionProxyHandler.extractPhysicalConnection(ConnectionProxyHandler.java:82)
at org.hibernate.engine.jdbc.internal.proxy.ConnectionProxyHandler.continueInvocation(ConnectionProxyHandler.java:138)
at org.hibernate.engine.jdbc.internal.proxy.AbstractProxyHandler.invoke(AbstractProxyHandler.java:81)
at $Proxy5.prepareStatement(Unknown Source)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:147)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:166)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:145)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1739)
at org.hibernate.loader.Loader.doQuery(Loader.java:828)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:289)
at org.hibernate.loader.Loader.doList(Loader.java:2463)
at org.hibernate.loader.Loader.doList(Loader.java:2449)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2279)
at org.hibernate.loader.Loader.list(Loader.java:2274)
at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:331)
at org.hibernate.internal.SessionImpl.listCustomQuery(SessionImpl.java:1585)
at org.hibernate.internal.AbstractSessionImpl.list(AbstractSessionImpl.java:224)
at org.hibernate.internal.SQLQueryImpl.list(SQLQueryImpl.java:156)
at com.cisco.cstg.np.summarizer.util.HibernateUtil.executeQuery(HibernateUtil.java:373)
at com.cisco.cstg.np.summarizer.dao.NPSummaryDao.getListOfDecimal(NPSummaryDao.java:154)
at com.cisco.cstg.np.summarizer.summarizer.hweox.HWEoxSummarizer.getChassisModuleFanPwCount(HWEoxSummarizer.java:581)
at com.cisco.cstg.np.summarizer.summarizer.hweox.HWEoxSummarizer.getSummaryByMileStone(HWEoxSummarizer.java:474)
at com.cisco.cstg.np.summarizer.summarizer.hweox.HWEoxSummarizer.processHwEox(HWEoxSummarizer.java:182)
at com.cisco.cstg.np.summarizer.summarizer.hweox.HWEoxSummarizer.access$100(HWEoxSummarizer.java:31)
at com.cisco.cstg.np.summarizer.summarizer.hweox.HWEoxSummarizer$ProcessGroup.call(HWEoxSummarizer.java:892)
at com.cisco.cstg.np.summarizer.summarizer.hweox.HWEoxSummarizer$ProcessGroup.call(HWEoxSummarizer.java:867)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.sql.SQLException: An SQLException was provoked by the following failure: java.lang.InterruptedException
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:65)
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:62)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:531)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at org.hibernate.service.jdbc.connections.internal.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:79)
at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:276)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:297)
... 32 more
Caused by: java.lang.InterruptedException
at java.lang.Object.wait(Native Method)
at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1315)
at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)