Monitoring Open and Cached Cursors

To monitor open cursors, query v$sesstat where name='opened cursors current'. This will give the number of currently opened cursors, by session:

--total cursors open, by session
select a.value, s.username, s.sid, s.serial#
from v$sesstat a, v$statname b, v$session s
where a.statistic# = b.statistic#  and s.sid=a.sid
and b.name = 'opened cursors current';

If you're running several N-tiered applications with multiple webservers, you may find it useful to monitor open cursors by username and machine:

--total cursors open, by username & machine
select sum(a.value) total_cur, avg(a.value) avg_cur, max(a.value) max_cur, 
s.username, s.machine
from v$sesstat a, v$statname b, v$session s 
where a.statistic# = b.statistic#  and s.sid=a.sid
and b.name = 'opened cursors current' 
group by s.username, s.machine
order by 1 desc;