SELECT 
SUBSTR(s1.username,1,12) "WAITING USER"
, SUBSTR(s1.osuser,1,8) "OS User"
, SUBSTR(TO_CHAR(w.session_id),1,5) "Sid"
, p1.spid "PID"
, SUBSTR(s2.username,1,12) "HOLDING User"
, SUBSTR(s2.osuser,1,8) "OS User"
, SUBSTR(TO_CHAR(h.session_id),1,5) "Sid"
, p2.spid "PID"
FROM
sys.v_$process p1
, sys.v_$process p2
, sys.v_$session s1
, sys.v_$session s2
, dba_locks w
, dba_locks h
WHERE
h.mode_held != 'None'
AND h.mode_held != 'Null'
AND w.mode_requested != 'None'
AND w.lock_type (+) = h.lock_type
AND w.lock_id1 (+) = h.lock_id1
AND w.lock_id2 (+) = h.lock_id2
AND w.session_id = s1.sid (+)
AND h.session_id = s2.sid (+)
AND s1.paddr = p1.addr (+)
AND s2.paddr = p2.addr (+)