Blocking Session Details

How to find blocking / locking session details:

set lines 145
col sid noprint

select distinct
       s1.sid,s1.username || '@' || s1.machine ||
       ' ( INST=' || s1.inst_id || ' SID=' || s1.sid||','||s1.serial# ||'  '||s1.status||': '||s1.last_call_et||' SQLID: '||s1.sql_id||' )  is blocking '
       || s2.username || '@' || s2.machine || ' ( INST=' || s1.inst_id || ' SID=' || s2.sid || ' ) ' AS blocking_status
  from gv$lock l1, gv$session s1, gv$lock l2, gv$session s2
where s1.sid=l1.sid
   and s2.sid=l2.sid
   and l1.BLOCK=1
   and l2.request > 0
   and l1.id1 = l2.id1
   and l2.id2 = l2.id2
   and l1.inst_id = s1.inst_id
order by s1.sid;

Output:

BLOCKING_STATUS
-------------------------------------------------------------------------------------------------------------------------------------------------
APPS@mydbserver ( INST=1 SID=6323,26775  ACTIVE: 2494 SQLID: 08pfumd9shm53 )  is blocking APPS@mydbserver ( INST=1 SID=6323 )

1 row selected.

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