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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 FEBRUARY 01, 2022

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.


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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