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This wait type occurs when a parallel thread in a DBCC CHECKDB (or similar) command is waiting for one or more other such threads to finish initializing, or finish exiting when certain unexpected errors occur that terminate the command (not including simply killing the command manually).
(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 1109 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.
This is usually a benign wait that always occurs for a parallel DBCC operation.
I’ve heard anecdotal evidence of a potential bug where a DBCC CHECKDB will fail for some reason and then hang with one or more threads waiting for this wait type. Microsoft are aware of the issue, but as of 7/23/19 I don’t know of any fix.
Known occurrences in SQL Server (list number matches call stack list):
- Waiting for other another parallel thread to finish initializing during a DBCC CHECKDB
Abbreviated call stacks (list number matches known occurrences list):