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BROKER_TASK_STOP

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Description:

Paraphrased from the old Service Broker team blog: This wait type is when one of the Service Broker internal task handlers is waiting for up to ten seconds to shut down because there are no Service Broker internal tasks (transmission and receipt of messages or other asynchronous network operations) for it to handle.

(Books Online description: “Occurs when the Service Broker queue task handler tries to shut down the task. The state check is serialized and must be in a running state beforehand.”)

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Added in SQL Server version:

Pre-2005/2005

Removed in SQL Server version:

N/A

Extended Events wait_type value:

Maps to the SSB_TASK_STOP map_value in sys.dm_xe_map_values (thanks to Jonathan’s post here).

The map_key value in sys.dm_xe_map_values is 291 in 2008 and 2008 R2, 334 in 2012, and 348 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. Service Broker always schedules a background cleanup task every 5 seconds, when Service Broker is being used, this wait type will increase by 5 seconds every 5 seconds. When Service Broker isn’t being used, this wait type will increase by ten seconds each time a database is brought online or offline (or created or dropped).

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

  1. Waiting for a Service Broker task to stop

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

  1. SOS_Task::PostWait+90
    EventInternal<SuspendQueueSLock>::Wait+25c
    CSbTaskHandler::Stop+b0
    CSbTaskManager::HandleReusableTask+840
    CSbTask::TaskStart+14b
    CSbTask::BeginTaskStart+17
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+a8