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This wait type seems to be a generic wait for background worker threads involved in in-memory table processing. Note that this is a preemptive wait, so the thread continues executing on the processor until the work is complete.

(Books Online description: “Internal use only.”)

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Added in SQL Server version:


Removed in SQL Server version:


Extended Events wait_type value:

The map_key value in sys.dm_xe_map_values is 1065 in 2016 RTM. After 2016 RTM, you must check the DMV to get the latest value as some map_key values have changed in later builds.

Other information:

Anecdotal evidence suggests that this wait type may become a bottleneck when using the Telemetry Extended Events session.

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

  1. An in-memory background worker thread ending a period of running in preemptive mode.

And other similar call stacks.

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

  1. sqldk.dll!SOS_Task::PopWait+0x107