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BROKER_TO_FLUSH

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Description:

This wait type is when a thread is waiting for the writing out of inactive transmission objects (that track message transmissions for a dialog) to a tempdb worktable to save memory. See the Service Broker Transmission Objects section of Books Online here for more information.

(Books Online description: “Occurs when the Service Broker lazy flusher flushes the in-memory transmission objects to a work table.”)

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Added in SQL Server version:

2008

Removed in SQL Server version:

N/A

Extended Events wait_type value:

The map_key value in sys.dm_xe_map_values is 350 in 2008 and 2008 R2, 397 in 2012, and 413 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 inactive transmission objects to be flushed to tempdb

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

  1. SOS_Task::PostWait+9e
    EventInternal<SuspendQueueSLock>::Wait+25e
    CSbTransmissionLazyFlusher::LazyFlushTask+2ea
    CSbTask::TaskStart+14b
    CSbTask::BeginTaskStart+17
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab