Starting in Oracle Database 12c, the multithreaded Oracle model enables specific Oracle processes to execute as operating system threads in separate address spaces. Setting up an Oracle database instance for using multi-process multi-thread architecture is done by starting up the Oracle database instance with the THREADED_EXECUTION initialization parameter set to TRUE.

The multi-process multi-thread model requires a password file for SYSDBA authentication while starting the database instance. Without using the SYS password

an  ORA-1031: insufficient privileges error will be triggered on startup.

When the THREADED_EXECUTION parameter is set to TRUE, you must set the DEDICATED_THROUGH_BROKER_LISTENER parameter to ON in your listener.ora file.

When that parameter is set, the listener knows that it should not spawn an OS process when a connect request is received; instead, it passes the request to the database so that a database thread is spawned and answers the connection.