The Lock Viewer portlet allows you to view the lock data such as transaction identifiers, session identifiers, lock object identifiers, and global deadlocks. Viewing lock information helps you determine whether system performance has been degraded by a database lock.
You can locate locks in a specific database, in a specific time frame, caused by a specific user, or that are blocking a specific user. You can also view details about selected sessions, including details about other queries that are blocking the session you select, what time the query started, and when the query became blocked.