Performance Tuning: PROCESSES

      The PROCESSES initialization parameter determines the maximum number of operating system processes that can be connected to Oracle Database concurrently. The value of this parameter must be a minimum of one for each background process plus one for each user process. The number of background processes will vary according the database features that you are using. For example, if you are using Advanced Queuing or the file mapping feature, you will have additional background processes. If you are using Automatic Storage Management, then add three additional processes for the database instance.

If you plan on running 50 user processes, a good estimate would be to set the PROCESSES initialization parameter to 70.

To count current number of process on database:
SQL> select count(*) from v$process;

  COUNT(*)
----------
       368

To display current value of process on database:
SQL> show parameter process

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
processes                            integer     6000
SQL>


To display current value of process on os:
$ ulimit -u
131072

To count current number of process on os:
ps -ef|wc -l
1299

To set value in database:
SQL> alter system set process=6000 scope=spfile;

To set value in OS:
vi /etc/security/limits.conf
orausr     soft    nproc       131072
orausr     hard   nproc       131072