record is locked by another user

1.问题：Record is locked by another user?

select t2.username,t2.sid,t2.serial#,t2.logon_time
from v$locked_object t1,v$session t2
where t1.session_id=t2.sid order by t2.logon_time;

2.--查看锁
--alter system kill session 'sid,serial#';
--把锁给KILL掉
alter system kill session '151,14678';

3.--查看表大小
selet bytes from dba_segment where segment_name='table_name'