To view locked objects in a Oracle DB

Below query can be used to view locked objects in a Oracle database..

SELECT C.OWNER,C.OBJECT_NAME,C.OBJECT_TYPE,B.SID,B.SERIAL#,B.STATUS,B.OSUSER,B.MACHINE
FROM V$LOCKED_OBJECT A ,
V$SESSION B,
DBA_OBJECTS C
WHERE B.SID = A.SESSION_ID AND
A.OBJECT_ID = C.OBJECT_ID

If you want to kill a session after finding out the locked session below is the statement to execute..

ALTER SYSTEM KILL SESSION '[SID],[SERIAL#]' ;