1. 

SELECT SID, DECODE(BLOCK, 0, 'NO', 'YES' ) BLOCKER, DECODE(REQUEST, 0, 'NO','YES' ) WAITER
FROM V$LOCK 
WHERE REQUEST > 0 OR BLOCK > 0 
ORDER BY block DESC;

2. 

SELECT bs.username "Blocking User", bs.username "DB User", 
        ws.username "Waiting User", bs.sid "SID", ws.sid "WSID", 
        bs.serial# "Serial#", bs.sql_address "address", 
        bs.sql_hash_value "Sql hash", bs.program "Blocking App", 
        ws.program "Waiting App", bs.machine "Blocking Machine", 
        ws.machine "Waiting Machine", bs.osuser "Blocking OS User", 
        ws.osuser "Waiting OS User", bs.serial# "Serial#", 
        ws.serial# "WSerial#", 
        DECODE (wk.TYPE, 
                'MR', 'Media Recovery', 
                'RT', 'Redo Thread', 
                'UN', 'USER Name', 
                'TX', 'Transaction', 
                'TM', 'DML', 
                'UL', 'PL/SQL USER LOCK', 
                'DX', 'Distributed Xaction', 
                'CF', 'Control FILE', 
                'IS', 'Instance State', 
                'FS', 'FILE SET', 
                'IR', 'Instance Recovery', 
                'ST', 'Disk SPACE Transaction', 
                'TS', 'Temp Segment', 
                'IV', 'Library Cache Invalidation', 
                'LS', 'LOG START OR Switch', 
                'RW', 'ROW Wait', 
                'SQ', 'Sequence Number', 
                'TE', 'Extend TABLE', 
                'TT', 'Temp TABLE', 
                wk.TYPE 
                ) lock_type, 
        DECODE (hk.lmode, 
                0, 'None', 
                1, 'NULL', 
                2, 'ROW-S (SS)', 
                3, 'ROW-X (SX)', 
                4, 'SHARE', 
                5, 'S/ROW-X (SSX)', 
                6, 'EXCLUSIVE', 
                TO_CHAR (hk.lmode) 
                ) mode_held, 
        DECODE (wk.request, 
                0, 'None', 
                1, 'NULL', 
                2, 'ROW-S (SS)', 
                3, 'ROW-X (SX)', 
                4, 'SHARE', 
                5, 'S/ROW-X (SSX)', 
                6, 'EXCLUSIVE', 
                TO_CHAR (wk.request) 
                ) mode_requested, 
        TO_CHAR (hk.id1) lock_id1, TO_CHAR (hk.id2) lock_id2, 
        DECODE (hk.BLOCK, 
                0, 'NOT Blocking', /* Not blocking any other processes */ 
                1, 'Blocking', /* This lock blocks other processes */ 
                2, 'Global', /* This lock is global, so we can't tell */ 
                TO_CHAR (hk.BLOCK) 
                ) blocking_others 
FROM v$lock hk, v$session bs, v$lock wk, v$session ws 
WHERE hk.BLOCK = 1 
AND hk.lmode != 0 
AND hk.lmode != 1 
AND wk.request != 0 
AND wk.TYPE(+) = hk.TYPE 
AND wk.id1(+) = hk.id1 
AND wk.id2(+) = hk.id2 
AND hk.sid = bs.sid(+) 
AND wk.sid = ws.sid(+) 
AND (bs.username IS NOT NULL) 
AND (bs.username <> 'SYSTEM') 
AND (bs.username <> 'SYS') 
ORDER BY 1;