PREEMPTIVE_OS_DELETESECURITYCONTEXT

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Description:

This wait type is when a thread is calling the Windows DeleteSecurityContext function.

(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 370 in 2008 and 2008 R2, 417 in 2012, and 433 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.

Note that when a thread calls out to Windows, the thread changes from non-preemptive (SQL Server controls the thread) to preemptive (Windows controls the thread) mode. The thread’s state will be listed as RUNNING, as SQL Server doesn’t know what Windows is doing with the thread.

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

1. Deleting a security context (in this case, while closing a connection from a client)
2. Deleting a security context (in this case, while disconnecting from a Service Broker conversation endpoint)

And other similar stacks.

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

1. SOS_Task::PopWait+b1
   SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7c
   SNI_Sec::DeleteSspi+21f
   SNIClose+b3
   CNetConnection::CloseNetlibEP+48
   CNetConnection::KillConnection+218
   CPhysicalConnection::NotifySessionLogout+eb
   CSession::LogoutSession+71f
   CSession::RemoveBatch+d3
   process_close_connection+12b
   process_commands+8e5
   SOS_Task::Param::Execute+21e
   SOS_Scheduler::RunTask+ab
2. SOS_Task::PopWait+b1
   SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7c
   SNI_Sec::DeleteSspi+21f
   CConnectionEndpoint::Release+dd
   CSbTaskManager::HandleReusableTask+5bc
   CSbTask::TaskStart+14b
   CSbTask::BeginTaskStart+17
   SOS_Task::Param::Execute+21e
   SOS_Scheduler::RunTask+ab