A graceful shutdown gives WebLogic Server subsystems time to complete certain application processing currently in progress. See Graceful Shutdown.
Waiting for abandoned HTTP sessions to timeout can significantly lengthen the graceful shutdown process because the default session timeout is one hour.
The Graceful Shutdown Timeout field specifies a time limit for a server instance to complete a graceful shutdown. If you supply a timeout value, and the server instance does not complete a graceful shutdown within that period, WebLogic Server performs a forced shutdown on the server instance.
If you supply a timeout value, and the server instance does not complete a graceful shutdown within that period, WebLogic Server performs a forced shutdown on the server instance.
If you do not supply a timeout value, the server waits indefinitely to complete a graceful shutdown.