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High Waits For "Channel Operations Parent Latch" Childlatch when Listening on Advancing Queueing Queues (Doc ID 790617.1)

Last updated on NOVEMBER 22, 2019

Applies to:

Oracle Database - Enterprise Edition - Version to [Release 10.2]
Oracle Database - Enterprise Edition - Version to [Release 11.1]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
Checked for relevance on 06 May 2013


An Advanced Queueing application is being used and there are multiple sessions performing Listen operations on single and multiple-consumer queues.

Running AWR report shows a very high number of "latch free" waits.

At certain periods of time there is very heavy contention for a particular "channel operations parent latch" (child#=59).  This latch is associated with the "AQ post/wait channel 1" broadcast channel.

An AWR snapshot  of latch locations shows: 

Latch NameWhere

NoWait Misses

SleepsWaiter Sleeps
channel operations parent latch ksrchreset() 0 442,410 72,469
  ksrwait()  0 257,833 468,204
  ksrapublish() 0 240,047 325,640
  ksrmfree() 0 100,181 28,638
  ksrsconsume() 0 36,337 104,506
  ksrsubscribe() 0 1,432 79,544
  ksrchdelete() 0 98 15

An example stack from a waiting session is

kwqilintl -> kwqidlisten -> ksrchreset -> ksrmfree -> kslgetsl


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