You can check the number of active users currently logged into the application using the following query.

select to_char(START_TIME,’DD-MON-YYYY’) Login_Time, count(*) cnt
from fnd_logins where START_TIME > (select to_date(’25-JAN-2008 00:00:00′,’DD-MON-YYYY HH24:MI:SS’) from dual)
and login_type is not null
and end_time is null
group by to_char(START_TIME,’DD-MON-YYYY’);

LOGIN_TIME               CNT
—————– ———-
26-JAN-2008               26
25-JAN-2008              132
28-JAN-2008               13
27-JAN-2008               34

Also you can check the number of user session for the application using ICX_SESSIONS table. Use below query for checking the number of user sessions.

select ((select sysdate from dual)),(select  ‘ user sessions : ‘ || count( distinct session_id) How_many_user_sessions
from icx_sessions icx
where disabled_flag != ‘Y’
and PSEUDO_FLAG = ‘N’
and (last_connect + decode(FND_PROFILE.VALUE(‘ICX_SESSION_TIMEOUT’), NULL,limit_time, 0,limit_time,FND_PROFILE.VALUE(‘ICX_SESSION_TIMEOUT’)/60)/24) > sysdate
and counter < limit_connects) from dual

((SELECTSYSDATE (SELECT’USERSESSIONS:’||COUNT(DISTINCTSESSION_ID)HOW_MANY
————— ———————————————————
28-JAN-08        user sessions : 9