Queue Monitor Coordinator Process consuming 100% of 1 cpu

	Doc ID:	604246.1	Type:	PROBLEM
	Modified Date :	14-JUL-2008	Status:	MODERATED

In this Document
  Symptoms
  Cause
  Solution
  References

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Applies to:

Oracle Server - Enterprise Edition - Version: 10.1.0.1.0 to 10.2.0.3.0
This problem can occur on any platform.

Symptoms

The Queue Monitor Coordinator (QMNC) process is consuming 100% cpu of a single core.

Short errorstacks for the process look like

<-kslpstevent() <-kslpsem() <-kwqmnchslvs() <-kwqmncoord()

aq_tm_processes has been set manually to 10.

Cause

The cause of this problem has been identified and verified in an unpublished bug 5484652. It is caused by the Queue Monitor Coordinator process spinning when it is unable to start a new qmon slave process to start to handle that task.

Solution

Download and apply Patch 5484652.

If aq_tm_processes=10 then set it to 1 via

connect / as sysdba

alter system set aq_tm_processes=1;

As per Note 305662.1 this parameter does not need to be set at all in 10.1 onwards

To unset the parameter:

When using a pfile:

Comment out or remove the aq_tm_processes entry, and restart the database.

When using a spfile:

connect / as sysdba
alter system reset aq_tm_processes scope=spfile sid='*';

and restart the database

References

Note 305662.1 - Queue Monitor Process: Architecture and Known Issues

Keywords

AQ_TM_PROCESSES; QMNC; SPINNING~PROCESS;