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This wait type is exactly as described by the Books Online entry (although the second sentence should say ‘SQL Server *also* uses this wait state…). Note that this is a preemptive wait, so the thread will continue executing on the processor until the XP completes.
(Books Online description: “Occurs when a task is waiting for an extended stored procedure to end. SQL Server uses this wait state to detect potential MARS application deadlocks. The wait stops when the extended stored procedure call ends.”)
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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 200 in 2008 and 2008 R2, 207 in 2012, and 214 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.
If this wait type becomes prevalent on your server, identify which of your extended stored procedures are being executed (using my script) and then troubleshoot the XP code.
Known occurrences in SQL Server (list number matches call stack list):
- Waiting for an XP call to complete
Abbreviated call stacks (list number matches known occurrences list):