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This wait type is when a thread is waiting for access to the data structure that holds the various timers used by the Extended Events engine (e.g., a timer used to implement the MAX_DISPATCH_LATENCY property of a target).
(Books Online description: N/A)
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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 343 in 2008 and 2008 R2, 390 in 2012, and 406 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.
I have not seen this wait type be a noticeable contention point.
Known occurrences in SQL Server (list number matches call stack list):
- Waiting for access to the timer list (in this case, to determine whether a timer has expired)
And other similar call stacks for adding and removing timers.
Abbreviated call stacks (list number matches known occurrences list):