How to check locks and kill sessions in Oracle Database?

The below script will tell which session is holding the lock

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
/


The below command is used to kill the session from oracle

ALTER SYSTEM KILL SESSION 'SID,Searial#' IMMEDIATE ;

ALTER SYSTEM KILL SESSION '1626,19894' IMMEDIATE ;

ALTER SYSTEM DISCONNECT SESSION '13, 8' IMMEDIATE ;

How to check the locked objects in the Oracle Database?

Below is the script to check the locked objects in the Oracle Database

SELECT oracle_username USERNAME,
owner OBJECT_OWNER,
object_name, object_type, s.osuser,
s.SID SID,
s.SERIAL# SERIAL,
DECODE(l.block,
0, 'Not Blocking',
1, 'Blocking',
2, 'Global') STATUS,
DECODE(v.locked_mode,
0, 'None',
1, 'Null',
2, 'Row-S (SS)',
3, 'Row-X (SX)',
4, 'Share',
5, 'S/Row-X (SSX)',
6, 'Exclusive', TO_CHAR(lmode)
) MODE_HELD
FROM gv$locked_object v, dba_objects d,
gv$lock l, gv$session s
WHERE v.object_id = d.object_id
AND (v.object_id = l.id1)
and v.session_id = s.sid
ORDER BY oracle_username, session_id;

Note: Run the above select statement as sys user.