monitor oracle locks

monitor oracle locks

i want to monitor ROacle locks.  More specifically i want to monitor if any session is waiting longer than 3 minutes.  HOw can i set such an alarm?  OR better yet what is the best way to monitor this type of issue.  I know i cna run a SQL query like this to get my answer but is there a way besides the database query monitor.

select 'Count' as PK1,count(1) from gv$lock where request > 0 and ctime > 200

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