maximum concurrent user in the system

Hi:

We are using EBS version 12.2.4

In the oracle application manager dashboard user monitoring, I can see what user are currently login with concurrent program or form.

I found a query on the website which can tell the number of user currently log in to EBS; however, that query is running forever.

select count(distinct d.user_name) from apps.fnd_logins a,

v$session b, v$process c, apps.fnd_user d

where b.paddr = c.addr

and a.pid=c.pid

and a.spid = b.process

and d.user_id = a.user_id

and (d.user_name = 'USER_NAME' OR 1=1)