在Oracle中可以通过dba_hist_active_sess_history视图查看并发的会话，可以通过以下脚本查询出每个用户最大并发，当前的连接数，及profile限制的最大连接数等。
SELECT AA.USERNAME, AA.MT, BB.CNT, CC.LIMIT, AA.MN, AA.AG
FROM (select username, max(cnt) MT, min(cnt) MN, avg(cnt) AG
from (select username, snap_id, count(1) cnt
from dba_hist_active_sess_history a, dba_users b
where --user_id = 65
-- sample_time >= to_date('2014-06-27', 'yyyy-mm-dd')
--and sample_time < to_date('2014-10-29', 'yyyy-mm-dd')
----and snap_id>=37306 and snap_id < 37401
--snap_id>=36062 and snap_id < 38073 285240710
a.user_id = b.user_id
group by username, snap_id)
group by username) AA,
(SELECT USERNAME, COUNT(1) CNT FROM V$SESSION GROUP BY USERNAME) BB,
(SELECT B.USERNAME, A.LIMIT
FROM dba_profiles A, DBA_USERS B
WHERE A.PROFILE = B.PROFILE
and b.account_status = 'OPEN'
AND A.resource_name = 'SESSIONS_PER_USER') CC
WHERE AA.USERNAME = BB.USERNAME
AND BB.USERNAME = CC.USERNAME;
结果如下：
USERNAME MT CNT LIMIT MN AG
APP_user1 14 100 100 1 1.790323
APP_user2 6 100 100 1 1.571429
APP_user3 3 100 100 1 1.328125
APP_user4 6 100 100 1 1.425532
APP_user5 6 100 100 1 1.753846