Get blocking session information

 

find out whose session is blocking whom

select l1.sid "holder",l2.sid "waiter" from v$lock l1,v$lock l2 where     l1.id1=l2.id1 and l1.id2=l2.id2 and l1.block=1 and l2.request>0 order by l1.sid;

Get the each session info using the below query

set line 150
col program for a20
col MODULE for a20
col action for a20
col user@machine 	for a30
col (SID,SERIAL#) 	for a15
set line 150
select '('||sid||','||serial#||')' "(SID,SERIAL#)",last_call_et/3600,status,username||'@'||machine as "user@machine",program,module,action
from v$session where sid=&SID;

action – will tell you the Name of the currently executing action.
Ex: concurrent request,JDBC Thin Client, FRM*- form session

status – will tell you whether the session is active or inactive

If it is an inactive form session inform the user to log off and log back. If the user has logged off and still the lock exists then you can kill the form session.