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Description:
This wait type is when a thread is waiting for an event dispatch timer to expire as part of implementing the MAX_DISPATCH_LATENCY setting for an Extended Event session asynchronous target.
(Books Online description: N/A)
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Added in SQL Server version:
2008
Removed in SQL Server version:
N/A
Extended Events wait_type value:
The map_key value in sys.dm_xe_map_values is 344 in 2008 and 2008 R2, 391 in 2012, and 407 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:
I have not seen this wait type be a noticeable contention point.
This wait type is one that I usually filter out as a benign wait when doing wait statistics analysis.
Known occurrences in SQL Server (list number matches call stack list):
- Waiting for an event session dispatch timer to expire
Abbreviated call stacks (list number matches known occurrences list):
- SOS_Task::PostWait+9e
EventInternal<SuspendQueueSLock>::Wait+2aa
SOSHost_EventAuto::Wait+33
XE_Timer::Run+9c
XE_Timer::EntryPointWithContext+148
XESQLSetupThreadContext+e6
XE_Timer::EntryPoint+28
SOS_Task::Param::Execute+21e
SOS_Scheduler::RunTask+ab