DBSNMP sessions use too much CPU

 Dear all,
I have installed Oracle Database 11g 11.2.0.2.0. Everything works fine, the database works smoothly for two months without any problem. Anyhow, I have configured Oracle Data Guard using Oracle Data Guard Broker. The configuration went successful and the Redo is shipping just great.

The problem now is with the DBSNMP user. Once we log on to the DB Control, the DBSNMP user started a session with the following SQL statement:

/* OracleOEM */

SELECT 'proxy_account',

        c             ,

        'NA'

FROM

        (

                SELECT DISTINCT c

                FROM

                        (

                                SELECT   NULL  p,

                                        name c

                                FROM    system_privilege_map

                                WHERE   name <> 'CREATE SESSION'

                                UNION

                                SELECT granted_role p, grantee c