PREEMPTIVE_OS_DELETESECURITYCONTEXT

(Republishing, or using this info in a commercial product/website, is prohibited without permission. All other uses are permitted. If in doubt, please ask.)

(Back to main page…)

Description:

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

(Books Online description: N/A)

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:

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