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HADR_NOTIFICATION_DEQUEUE

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Description:

This wait type is just as the Books Online entry describes.

(Books Online description: “A background task that processes Windows Server Failover Clustering notifications is waiting for the next notification.  Internal use only.”)

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Added in SQL Server version:

2012

Removed in SQL Server version:

N/A

Extended Events wait_type value:

The map_key value in sys.dm_xe_map_values is 836 in 2012 and 855 in 2014 RTM. After 2014 RTM, you must check the DMV to get the latest value as some map_key values have changed in later builds.

Other information:

I have not seen this wait type be a noticeable contention point.

This wait type is one that I usually filter out as a benign wait when doing wait statistics analysis.

Known occurrences in SQL Server (list number matches call stack list):

  1. Waiting for a failover cluster notification

Abbreviated call stacks (list number matches known occurrences list):

  1. SOS_Task::PostWait+90
    EventInternal<SuspendQueueSLock>::Wait+2c6
    ResQueueBase::Dequeue+1cf
    CHadrNotificationWorker::RunThread+151
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+a8