Your applications possibly is opening many sessions and don't close it.
if your database its Oracle you can execute this:
select username, count(1) from v$session group by username order by 2 desc;
if the top username its your application then check your application for how to close connections.
whats the username that these sessions are opened/created from?
after opening do they persist for long time ? or they kind of runaway processes.
from the operating system check with the ps -ef command for the user/application to take a note of currently running processes.
were there any recent changes ?
you can execute:
you can use many columns:
Pay atention at:
Operating system client user name
MACHINE VARCHAR2(64) Operating system machine name PROGRAM VARCHAR2(48) Operating system program name
If you have PID you can use the next query to looking for "SID"
select sid, s.serial# from v$session s, v$process p where paddr=addr and SPID=<PIDNUMBER>