SHUTDOWN Active processes prevent shutdown operation

Today when i am shut-downing one of the oracle database its taking lots of time and when i see the alert log its waiting for "SHUTDOWN: Active processes prevent shutdown operation" to close.

Alert log:
Job queue slave processes stopped
Waiting for dispatcher 'D000' to shutdown
All dispatchers and shared servers shutdown
Wed Jul 22 11:01:33 2015
SHUTDOWN: Active processes prevent shutdown operation
Wed Jul 22 11:06:34 2015
SHUTDOWN: Active processes prevent shutdown operation
Wed Jul 22 11:11:36 2015
SHUTDOWN: Active processes prevent shutdown operation
Wed Jul 22 11:16:30 2015
MMNL absent for 1234 secs; Foregrounds taking over
Wed Jul 22 11:16:37 2015
SHUTDOWN: Active processes prevent shutdown operation


Diag:

When i grep pmon and SID it shows only one LOCAL=YES connection but that's is my connection of shutdown statement

[oracle@ ~]$ ps -ef|grep SID
oracle     641     1  0  2013 ?        00:41:48 ora_pmon_SID
oracle     643     1  0  2013 ?        00:00:30 ora_psp0_SID
oracle     645     1  0  2013 ?        01:01:12 ora_mman_SID
oracle     647     1  0  2013 ?        01:39:28 ora_dbw0_SID
oracle     649     1  0  2013 ?        06:08:15 ora_lgwr_SID
oracle     651     1  0  2013 ?        01:59:31 ora_ckpt_SID
oracle     653     1  0  2013 ?        00:32:51 ora_smon_SID
oracle     655     1  0  2013 ?        00:00:08 ora_reco_SID
oracle     688     1  0  2013 ?        00:12:00 ora_arc0_SID
oracle     691     1  0  2013 ?        00:12:11 ora_arc1_SID
oracle   19906 19905  0 10:56 ?        00:00:00 oracleSID (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))
oracle   20004 19952  0 11:12 pts/5    00:00:00 tail -100f alert_SID.log
oracle   20043 20016  0 11:17 pts/6    00:00:00 grep SID

But when i grep complete oracle, i see some of the rman and defunct session.

[oracle@ ~]$ ps -ef|grep oracle

oracle   25327 25282  0  2014 pts/4    00:00:01 rman target /
oracle   25347 25327  0  2014 ?        00:00:38 [oracle] <defunct>
oracle   25348 25327  0  2014 ?        00:00:50 [oracle] <defunct>
oracle   25349 25327  0  2014 ?        00:01:00 [oracle] <defunct>
oracle   25350 25327  0  2014 ?        00:00:19 [oracle] <defunct>

Solution:
After killing process ID(kill -9 PID) rman and defunct session from other putty connection the database went down.