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 10.2.0.1 to 10.2.0.4 [Release 10.2]Oracle Database - Enterprise Edition - Version 11.1.0.6 to 11.1.0.7 [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.
Symptoms
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 Name | Where |
NoWait Misses | Sleeps | Waiter 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
Cause
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In this Document
| Symptoms |
| Cause |
| Solution |
| References |