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SQLNET.EXPIRE_TIME

Purpose

Use parameter SQLNET.EXPIRE_TIME to specify the time interval, in minutes, to send a probe to verify that client/server connections are active. Setting a value greater than 0 ensures that connections are not left open indefinitely, due to an abnormal client termination. If the probe finds a terminated connection, or a connection that is no longer in use, it returns an error, causing the server process to exit. This parameter is primarily intended for the database server, which typically handles multiple connections at any one time.


DEAD CONNECTION DETECTION

DCD is initiated on the server when a connection is established. At this time SQL*Net reads the SQL*Net parameter files and sets a timer to generate an alarm. The timer interval is set by providing a non-zero value in minutes for the SQLNET.EXPIRE_TIME parameter in the sqlnet.ora file. When the timer expires, SQL*Net on the server sends a "probe" packet to the client. (In the case of a database link, the destination of the link constitutes the server side of the connection.) The probe is essentially an empty SQL*Net packet and does not represent any form of SQL*Net level data,but it creates data traffic on the underlying proto .

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.