Killing a session in backend

Some times the "alter system kill session" command will returns the output as "Marked as Killed".

in that case we need to kill the session from backend below are the steps:

Finding os process id using sid:---

select vs.sid,vs.serial#, vs.username, vs.osuser,vs.sql_id, vs.process fg_pid, vp.spid bg_pid from v$session vs, v$process vp where vs.paddr = vp.addr and vs.sid=<sid>;

output will get Background process id. use below OS command to kill the session.

Grip the
Kill -9 <background process id>