oracle 程序老是出現Io exception: Socket read timed out

2016-11-05 21:32:32,068 INFO [main] NumIdle: 0
2016-11-05 21:32:32,273 ERROR [main] java.sql.SQLException:null Io exception: Socket read timed out
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:113)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:147)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:257)
at oracle.jdbc.driver.T4CStatement.executeForRows(T4CStatement.java:985)
at oracle.jdbc.driver.OracleStatement.executeMaybeDescribe(OracleStatement.java:1074)
at oracle.jdbc.driver.T4CStatement.executeMaybeDescribe(T4CStatement.java:845)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1156)
at oracle.jdbc.driver.OracleStatement.executeQuery(OracleStatement.java:1315)
at org.apache.commons.dbcp.DelegatingStatement.executeQuery(DelegatingStatement.java:208)
at com.XXXXXX.fetchWorkOrders(XXXXX.java:366)
at com.XXXXXXXX.main(XXXXXX.java:250)

2016-11-05 21:32:32,273 ERROR [main] latestRstBean is null
2016-11-05 21:32:32,274 ERROR [main] java.sql.SQLException:null Already closed.
at org.apache.commons.dbcp.PoolableConnection.close(PoolableConnection.java:84)
at org.apache.commons.dbcp.PoolingDriver$PoolGuardConnectionWrapper.close(PoolingDriver.java:269)
at com.XXXXXXX.fetchWorkOrders(XXXXXXX.java:419)
at com.XXXXXXX.main(XXXXXXXXX.java:250)

如今在找緣由，問題這種狀況不是每次都會出現的。