Last updated on MAY 06, 2013
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]
Information in this document applies to any platform.
Checked for relevance on 06 May 2013
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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