How to find database table lock and send alerts

CREATE OR REPLACE PROCEDURE lock_monitor
IS
    v_connection UTL_SMTP.connection;
BEGIN
    v_connection := UTL_SMTP.open_connection('your.email.server.com');
    UTL_SMTP.helo(v_connection, 'your.domain.com');
    UTL_SMTP.mail(v_connection, 'your_return_address@your.domain.com');
    UTL_SMTP.rcpt(v_connection, 'your_recipient@your.domain.com');
    UTL_SMTP.open_data(v_connection);
    UTL_SMTP.write_data(v_connection, 'From: Lock Monitor' || UTL_TCP.crlf);
    UTL_SMTP.write_data(v_connection, 'To: AAA group' || UTL_TCP.crlf);
    UTL_SMTP.write_data(v_connection, 'Subject: Long lock held' || UTL_TCP.crlf);
 
    UTL_SMTP.write_data(v_connection, UTL_TCP.crlf);
    UTL_SMTP.write_data(v_connection, 'Locks found' || UTL_TCP.crlf);
 
    FOR x
    IN (SELECT lk.sid,
               se.username,
               se.osuser,
               se.machine,
               DECODE(lk.TYPE, 'TX', 'Transaction', 'TM', 'DML', 'UL', 'PL/SQL User Lock', lk.TYPE)
                   lock_type,
               DECODE(
                   lk.lmode,
                   0, 'None',
                   1, 'Null',
                   2, 'Row-S (SS)',
                   3, 'Row-X (SX)',
                   4, 'Share',
                   5, 'S/Row-X (SSX)',
                   6, 'Exclusive',
                   TO_CHAR(lk.lmode)
               )
                   mode_held,
               DECODE(
                   lk.request,
                   0, 'None',
                   1, 'Null',
                   2, 'Row-S (SS)',
                   3, 'Row-X (SX)',
                   4, 'Share',
                   5, 'S/Row-X (SSX)',
                   6, 'Exclusive',
                   TO_CHAR(lk.request)
               )
                   mode_requested,
               TO_CHAR(lk.id1) lock_id1,
               TO_CHAR(lk.id2) lock_id2,
               ob.owner,
               ob.object_type,
               ob.object_name,
               DECODE(
                   lk.block,
                   0,
                   'No',
                   1,
                   'Yes',
                   2,
                   'Global'
               )
                   block,
               se.lockwait,
               lk.ctime held_for_seconds
        FROM   v$lock lk, dba_objects ob, v$session se
        WHERE  lk.TYPE IN ('TM', 'UL')
           AND lk.sid = se.sid
           AND lk.id1 = ob.object_id
           AND lk.ctime > 600)
    LOOP
        UTL_SMTP.write_data(
            v_connection,
               x.sid
            || ' '
            || x.username
            || ' '
            || x.osuser
            || ' '
            || x.machine
            || ' '
            || x.lock_type
            || ' '
            || x.mode_held
            || ' '
            || x.mode_requested
            || ' '
            || x.lock_id1
            || ' '
            || x.lock_id2
            || ' '
            || x.owner
            || ' '
            || x.object_type
            || ' '
            || x.object_name
            || ' '
            || x.block
            || ' '
            || x.lockwait
            || ' '
            || x.held_for_seconds
            || UTL_TCP.crlf
        );
    END LOOP;
 
 
    UTL_SMTP.close_data(v_connection);
    UTL_SMTP.quit(v_connection);
EXCEPTION
    WHEN OTHERS
    THEN
        DBMS_OUTPUT.put_line(DBMS_UTILITY.format_error_stack);
END;

                                              

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REM    The report generated by this script gives information on sessions 
REM    which are holding locks and gives the information needed to kill 
REM    using the ALTER SYSTEM KILL SESSION command. 
REM ------------------------------------------------------------------------ 
REM Main text of script follows: 
 
set linesize 180 pagesize 66 
break on Kill on username on terminal 
column Kill heading 'Kill String' format a13 
column res heading 'Resource Type' format 999 
column id1 format 9999990 
column id2 format 9999990 
column lmode heading 'Lock Held' format a20 
column request heading 'Lock Requested' format a20 
column serial# format 99999 
column username  format a10  heading "Username" 
column terminal heading Term format a10
column OSuser heading OSuser format a15
column machine heading Machine format a10 
column tab format a35 heading "Table Name" 
column owner format a9 
column Address format a18 
select	nvl(S.USERNAME,'Internal') username, 
	nvl(S.TERMINAL,'None') terminal,
        nvl(S.MACHINE,'None') machine,
        nvl(S.OSUSER,'None') OSuser,    
	L.SID||','||S.SERIAL# Kill, 
	U1.NAME||'.'||substr(T1.NAME,1,20) tab, 
	decode(L.LMODE,1,'No Lock', 
		2,'Row Share', 
		3,'Row Exclusive', 
		4,'Share', 
		5,'Share Row Exclusive', 
		6,'Exclusive',null) lmode, 
	decode(L.REQUEST,1,'No Lock', 
		2,'Row Share', 
		3,'Row Exclusive', 
		4,'Share', 
		5,'Share Row Exclusive', 
		6,'Exclusive',null) request 
from	V$LOCK L,  
	V$SESSION S, 
	SYS.USER$ U1, 
	SYS.OBJ$ T1 
where	L.SID = S.SID  
and	T1.OBJ# = decode(L.ID2,0,L.ID1,L.ID2)  
and	U1.USER# = T1.OWNER# 
and	S.TYPE != 'BACKGROUND' 
order by   username, terminal, machine, lmode
--order by 1,2,6 
/ 
                                              

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