Queue Monitor process Memory Consumption increases due to a Leak

(Doc ID 233101.1)

Last updated on SEPTEMBER 01, 2015

Applies to:

Oracle Database - Enterprise Edition - Version to [Release 8.1.7 to 9.2]
Information in this document applies to any platform.


Over the course of time, the QMNx background process will slowly consume PGA memory. This eventually leads to performance degradation and potentially system instability. Because this usually occurs at 10 megs of memory or less per day, it isn't always evident that this defect is occurring until a significant chunk of the PGA is lost. The memory can be recovered by stopping and restarting the QMN process as sys via

alter system set aq_tm_processes=0;

and restarting them via


alter system set aq_tm_processes=<previous_value>;



To confirm that you are hitting this issue when the QMON process(s) are sufficiently large issue the following as sys

alter session set events 'immediate trace name heapdump level 29';

The problem is characterized by the following types of entries;

Chunk 1ff61f4 sz= 996 freeable "callheap " ds=1863208
Chunk 1ff65d8 sz= 1072 freeable "callheap " ds=1863208
Chunk 1ff6a08 sz= 1072 freeable "callheap " ds=1863208
Chunk 1ff6e38 sz= 1072 freeable "callheap " ds=1863208
Chunk 1ff7268 sz= 1072 freeable "callheap " ds=1863208
Chunk 1ff7698 sz= 1072 freeable "callheap " ds=1863208
Chunk 1ff7ac8 sz= 1072 freeable "callheap " ds=1863208
Chunk 1ff7ef8 sz= 1072 freeable "callheap " ds=1863208


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