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This latch class is when a thread is waiting for access to the cache of Windows security information (called WSPI entries – Windows Security Primary Info) that is used for login tokens.
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Added in SQL Server version:
Removed in SQL Server version:
Extended Events latch_class value:
Maps to the SECURITY_WSPI_LOOKUP map_value in sys.dm_xe_map_values.
The map_key value in sys.dm_xe_map_values is 137 in 2008 and 2008 R2, and 134 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’ve heard of several cases where contention happens on this latch if lots of users/threads need to use the same token at the same time. This can occur with concurrent multiple threads calling a stored proc that implicitly changes execution context using EXECUTE AS.
Known occurrences in SQL Server (list number matches call stack list):
Abbreviated call stacks (list number matches known occurrences list):