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Exactly as described below. Note that this is a preemptive wait, so the thread will continue executing on the processor until while the CLR task is starting.

(Books Online description: “Occurs while waiting for a CLR task to complete startup.”)

Questions/comments on this wait type? Click here to send Paul an email, especially if you have any information to add to this topic.

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 213 in 2008 and 2008 R2, 220 in 2012, and 227 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.

Known occurrences in SQL Server (list number matches call stack list):

  1. Waiting for a CLR task to start

Abbreviated call stacks (list number matches known occurrences list):

  1. SOS_Task::PostWait+4d
    EventInternal<Spinlock<153,1,0> >::Wait+1b2
    HostWait<EventManualInternal<Spinlock<153,1,0> > >+a4