(Republishing, or using this info in a commercial product/website, is prohibited without permission. All other uses are permitted. If in doubt, please ask.)
(Books Online description: “Occurs when an Extended Events session that is using asynchronous targets is started or stopped. This wait indicates either of the following: 1) An Extended Events session is registering with a background thread pool. 2) The background thread pool is calculating the required number of threads based on current load.”)
Questions/comments on this wait type? Click here to send Paul an email, especially if you have any information to add to this topic.
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 347 in 2008 and 2008 R2, 394 in 2012, and 410 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.
Known occurrences in SQL Server (list number matches call stack list):
Abbreviated call stacks (list number matches known occurrences list):