Try the following, taken from MOS note 1642867.1

To maintain the connections alive:

1. Set ENABLE=BROKEN parameter in the DESCRIPTION clause in the connection descriptor. For example:

jdbc:oracle:thin:@(DESCRIPTION=(ENABLE=BROKEN)(ADDRESS=(PROTOCOL=tcp)(PORT=<PORT>)(HOST=<HOSTNAME>))(CONNECT_DATA=(SERVICE_NAME=<SERVICE NAME>)))

2. And also set SQLNET.EXPIRE_TIME=10 in the database sqlnet.ora. This will enable Dead Connection Detection (DCD).

DCD is a keepalive mechanism. To summarize what DCD does:

* When a connection is established on the database, DCD is initiated.
* SQL*Net reads the SQLNET.EXPIRE_TIME parameter in the SQLNET.ORA file.
* Based on the value of this parameter, SQL*Net sets a timer to generate an "alarm".
* When this timer expires, SQL*Net sends a "probe" packet to the client.
* This is an empty SQL*Net packet; it doesn't contain data, but does create data traffic on the underlying protocol.
* If the client end of the connection is still active, the probe is discarded, and the timer mechanism is reset.
* If the client has terminated abnormally, the server will receive an error from the send call issued for the probe, and SQL*Net on the server will signal the operating system to release the connection's resources.

The (ENABLE=BROKEN) clause will work in conjunction with the server-side sqlnet.expire_time=10 , by enabling the JDBC driver to respond to the client probes sent by the server-side when the sqlnet.expire_time is reached. This will provide regular traffic on the sockets and prevent them from timing out.