to get blocking session in oracle

SELECT
   s.blocking_session,
   s.sid,
   s.serial#,
   s.seconds_in_wait
FROM
   v$session s
WHERE
   blocking_session IS NOT NULL;
 
 SELECT
   l1.sid || ' is blocking ' || l2.sid blocking_sessions
FROM
   v$lock l1, v$lock l2
WHERE
   l1.block = 1 AND
   l2.request > 0 AND
   l1.id1 = l2.id1 AND
   l1.id2 = l2.id2;
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
SELECT O.OBJECT_NAME, S.SID, S.SERIAL#, P.SPID, S.PROGRAM,S.USERNAME,
S.MACHINE,S.PORT , S.LOGON_TIME,SQ.SQL_FULLTEXT
FROM V$LOCKED_OBJECT L, DBA_OBJECTS O, V$SESSION S,
V$PROCESS P, V$SQL SQ
WHERE L.OBJECT_ID = O.OBJECT_ID
AND L.SESSION_ID = S.SID AND S.PADDR = P.ADDR
AND S.SQL_ADDRESS = SQ.ADDRESS;
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 alter system kill session '5031,2459';

++++++++++++++++++++ to find session details from concurrent req +++++++++++++++

SELECT a.request_id, d.sid, d.serial# ,d.osuser,d.process , c.SPID
FROM apps.fnd_concurrent_requests a,
apps.fnd_concurrent_processes b,
v$process c,
v$session d
WHERE a.controlling_manager = b.concurrent_process_id
AND c.pid = b.oracle_process_id
AND b.session_id=d.audsid
AND a.request_id =26916095;