QMON Slaves Processes Consuming High Amount of CPU after Upgrade to 126.96.36.199
Last updated on MAY 16, 2017
Applies to:Oracle Database - Enterprise Edition - Version 188.8.131.52 and later
Information in this document applies to any platform.
After upgrade to 184.108.40.206, you have observed that qmon slave processes (qXXX) are consuming a high amount of CPU.
To determine if you are suffering this problem, the following conditions should be met.
1) In AQ HC script (provided on Doc ID 1193854.1) html output, you can see :
a) At Statistics --> QMON section, the process consuming CPU are in status RUNNING and the task assigned are related to spilling like : QMON_SPILL or QMON_DEALLOC_SPILLED.
It can be idenfied using the following query too:
b) At Statistics --> Queues --> Buffered, there are buffered queues, but there are not buffered messages to spill:
num_msgs, spill_msgs, waiting, ready, expired, cnum_msgs, cspill_msgs, expired_msgs,
from gv$buffered_queues, gv$aq
order by 1,2,3;
2) A 10046/SQL trace for qmon slaves consuming cpu shows continous waits on 'library cache: mutex X' for the same idn all the time.
Upgrade to 220.127.116.11.
This issue has been observed on customer running EBS Workflow module, but can be observed on any type of queues.
It is more frequent to observe this issue on environment with ASMM (sga_target > 0) is being used and streams_pool_size parameter is not defined.
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