Instance registration in Oracle Net 12c behaves differently. In 12c and higher, there is a new background process called ora_lreg_sid-name.
In previous releases, PMON always handled instance registration logic. In 12c, LREG (Listener REGistration) now takes over with the instance registration logic.
LREG (Listener REGistration)
– Registers instance information with the listener.
– It is a critical background process for each database instance (if it is killed, Oracle goes down).
– It does everything PMON used to do and report: service_update, service_register, service_died in the listener.log.
LREG can be traced using the same methods as one would trace PMON:
- Enabling an Oracle Net server side sqlnet tracing will invoke a trace for LREG on instance startup.
- The old PMON trace command now traces LREG: alter system set events = ‘10257 trace name context forever, level 5’;
- Listener registration information can also be dumped into the ora_lreg trace file: alter system set events = ‘immediate trace name listener_registration level 3’;
- LREG can be traced dynamically.