The job of MMON( Manageability Monitor) background process is to perform tasks like taking AWR snapshots and automatic diagnostic analysis.
Sometime, MMON process crashes or get suspended .
Follow below steps to restart the MMON process:
1. Grant restricted session to public:
This grant is required to avoid any impact on the sessions connecting to database.
grant restricted session to public;
2. Enable and disable restricted sessions
Enabling and disabling will start the MMON process.
alter system enable restricted session; alter system disable restricted session;
3. Revoke the restricted session:
revoke restricted session from public;
4. Check MMON process;
ps -ef | grep mmon