Question: What does the QMNC
background task do?
Answer: The Queue Monitor Coordinator
(QMNC) background process is responsible for facilitating
various background activities required by Advanced Queuing
(AQ) and Oracle Streams.
The QMNC process was introduced in 10g release 1, and it
is responsible for allocating tasks to the QMON
sub-processes (q01, q02, . . . ) . Some of these tasks are
scheduled, while other tasks are event-driven
Here are the 12c AQ-related
The QMNC master process spawns slave processes named (Qnn)
and these background processes can be related to these wait
- AQ Background Master: slave start
- AQ Cross Master idle
- AQ master shutdown
- AQ master: time mgmt/task cleanup
- AQ propagation connection
- AQ reload SO release
- AQ slave: time mgmt/task cleanup
- AQ spill debug idle
- AQ: 12c message cache init wait
- AQ: non durable subscriber add or drop
The QMNC and Qnn processes are collectively referred to
as the Queue Monitor (QMON) processes.
The QMNC background process also manages non-persistent
(transient) queues, and resource cleanup.
Prior to Oracle 10g, the aq_tm_processes parameter
was used to control the
behavior of this spawning of AQ slaves (the maximum number
of slave processes for advanced queuing), and
aq_tm_processes should never be set to a value of zero.
In 10g and beyond, the aq_tm_processes parameter
is not used.
AQ Background Master: slave start wait. Also see my