How to find and investigate a process in top command output?

Total connection by machine:
SQL> select machine, count(*) from v$session group by machine order by 2;

Total number of database user who connected:
SQL> select count(1) "NO. Of DB Users Connected", to_char(sysdate,'DD-MON-YYYY:HH24:MI:SS') sys_time from v$session where username is NOT NULL;

Define a process(pid) from top:
17831 ora11g .. ora_m000_ALPERDB  

Get detailed info from database:
SQL> select * from v$process where spid = 17831;
-> M000 means MMON Slave Process
-> e.g. pid -> 16, sid -> 555

SQL>
SELECT s.username, osuser, process machine, p.terminal, type, sid, s.serial#, s.program
FROM v$session s, v$process p
WHERE p.pid = 16
AND s.paddr = p.addr;

SQL> select * from gv$session where sid = 555;

Get sql from below code related to example process if it has SQL:
SQL>
SELECT 
      s.sid
     ,s.CLIENT_INFO
     ,s.MACHINE
     ,s.PROGRAM
     ,s.TYPE
     ,s.logon_time
     ,s.osuser
     ,sq.sorts
     ,sq.DISK_READS
     ,sq.BUFFER_GETS
     ,sq.ROWS_PROCESSED
     ,sq.SQLTYPE
     ,sq.SQL_TEXT
 FROM gv$session s    
    , gv$sql sq
WHERE s.SQL_HASH_VALUE = sq.HASH_VALUE
  --AND s.inst_id= 1
  AND s.sid = 555 
  AND sq.inst_id= s.inst_id

How to define "idle_time" ?

Check parameter of resource_limit
SQL> show parameter resource;

If it is 'False'
SQL> alter system set resource_limit = true;

Add it into init.ora file permanently
*.resource_limit=true;

Modify default profile
SQL> alter profile default limit idle_time 1440;
-- 1440 -> 24 hour

Check default profile setting
SQL> select profile, resource_name, limit from dba_profiles 
where lower(profile) = 'default' and resource_name = 'IDLE_TIME';

Monitor idle sessions
SQL> select * from v$session where status = 'SNIPED' order by logon_time desc;

How to kill inactive session for non-background oracle processes?

At first, check the sessions
SQL>
SELECT DISTINCT spid, b.username, osuser
    FROM sys.dba_ddl_locks a, sys.v_$session B, v$process c
   WHERE     B.SID = a.session_id
         AND owner NOT IN ('SYS',
                           'WMSYS',
                           'CTXSYS',
                           'DBSNMP')
       AND B.TYPE <> 'BACKGROUND'
       AND B.status = 'INACTIVE'
         AND (c.addr = b.paddr)
ORDER BY username, osuser;

Kill the session
SQL>
SELECT DISTINCT
          'ALTER SYSTEM KILL SESSION '''
       || b.sid
       || ','
       || b.serial#
       || ''' IMMEDIATE;' AS KILL_THEM_ALL
  FROM sys.dba_ddl_locks a, sys.v_$session B
 WHERE     B.SID = a.session_id
       AND owner NOT IN ('SYS',
                         'WMSYS',
                         'CTXSYS',
                         'DBSNMP')
       AND B.TYPE <> 'BACKGROUND'
       AND B.status = 'INACTIVE'

How to kill remote sessions or specific sessions?

Observe remote sessions
$ ps -ef | grep LOCAL=NO | grep ALPERDB| awk '{print $2}'
$ ps -ef | grep LOCAL=NO | grep ALPERDB| wc -l

Kill all remote sessions
$ sudo kill -9 ` ps -ef|grep LOCAL=NO|grep ALPERDB|awk '{print $2}'`

Kill spesific sessions
SQL>
SELECT DISTINCT
          'ALTER SYSTEM KILL SESSION '''
       || b.sid
       || ','
       || b.serial#
       || ''' IMMEDIATE;'
  FROM sys.dba_ddl_locks a, sys.v_$session B
 WHERE     B.SID = a.session_id
       AND owner NOT IN ('SYS',
                         'WMSYS',
                         'CTXSYS',
                         'DBSNMP')
       AND B.TYPE <> 'BACKGROUND'
       AND name like '%EMPLOYEES%';

-- EMPLOYEES -> Table (Object) Name

Ref: https://ozsoyler.blogspot.com.tr/2017/01/how-to-kill-inactive-session-for-non.html