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Description:
Just as the Books Online description states.
(Books Online description: “Internal wait by a thread waiting for an async work task to complete. This is an expected wait and is for CSS use.”)
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:
2012
Removed in SQL Server version:
N/A
Extended Events wait_type value:
Maps to the HADR_WORKITEM_COMPLETED 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 763 in 2012 and 781 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:
Any time an asynchronous operation in an availability group is being waited for, this wait will occur. Examples of such operations are adding a database to an AG or dropping a database from an AG.
If this wait occurs for a long period of time, it is indicative of the operation stalling for some reason. I’ve heard of situations where removing a database from an AG hangs forever, with this wait type accumulating time on one thread. In such cases, a server reboot is required, and I would think that’s a SQL Server bug.
Known occurrences in SQL Server (list number matches call stack list):
- TBD
Abbreviated call stacks (list number matches known occurrences list):
- TBD