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This wait type is when a thread is waiting for exclusive access to a trace buffer in preparation for writing it to a trace file.
(Books Online description: “Occurs during synchronization on trace buffers during a file trace.”)
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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 161 in 2008 R2, and 165 in 2012 and 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):
- Getting access to a trace buffer before writing it to a trace file
And other similar call stacks.
Abbreviated call stacks (list number matches known occurrences list):