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PREEMPTIVE_XE_CALLBACKEXECUTE

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Description:

This wait type is when a thread is switching to preemptive mode before sending a message to the Extended Events engine through a callback mechanism.

(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 538 in 2008 and 2008 R2, 586 in 2012, and 602 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. Notifying the Extended Events Engine (in this case, while initializing of the system_health session)
  2. Notifying the Extended Events Engine (in this case, while removing an event from an event session)

And other similar call stacks.

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

  1. SOS_Task::PopWait+b1
    SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7a
    XE_NotificationManager::SendEngineNotification+1b6
    XE_Session::Commit+4a6
    XeSqlPkg::RouterTargetImpl<void __cdecl(XECollectedEvent const * __ptr64,XEEvent const * __ptr64,void * __ptr64),XECollectedEvent,XeSqlPkg::RouterTarget>::Add+ac
    EventSessionMgr::RegisterListeners+a3
    EventSessionMgr::Init+d5
    DiagEventSessionMgr::Init+14a
    DiagnoseComponentMgr::Execute+3fa
    SystemHealthMonitor+12b
    SystemHealthMonitorThread+94
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab
  2. SOS_Task::PopWait+b1
    SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7a
    XE_NotificationManager::SendEngineNotification+1b6
    XE_Session::NotifyEventDisabled+51
    XE_Session::Commit+2cb
    XE_Session::Close+205
    XE_Session::Destroy+33
    XE_Engine::ReleaseObjectReference+79
    XEventController::VLR_AlterXESession::~VLR_AlterXESession+77
    XEventController::VLR_StopXESession::CommitAndRelease+194
    XdesRMReadWrite::CommitAllVirtualLogRecs+e4
    XdesRMReadWrite::PreDestruct+23e
    XdesRMFull::~XdesRMFull+b2
    XdesRMFull::`vector deleting destructor’+14
    XactRM::SinglePhaseCommit+1e3
    XactRM::CommitInternal+472
    FullXactImp::Commit+33f
    CMsqlXactInternalReadWrite::Commit+19
    CMsqlXactImp::Commit+1d6
    CXStmtDDL::FinishNormalImp+e1
    CMsqlExecContext::ExecuteStmts<0,1>+9d8