PREEMPTIVE_XE_SESSIONCOMMIT

(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 switches to preemptive mode as part of committing changes to the list of Extended Event sessions on the instance.

(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 542 in 2008 and 2008 R2, 590 in 2012, and 606 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. Committing the event session changes (in this case, as part of a CREATE EVENT SESSION operation)
2. Committing the event session changes (in this case, as part of starting up the master database)

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_Session::Commit+4ff
   XE_Session::Close+325
   XE_Session::Destroy+33
   XE_Engine::ReleaseObjectReference+8e
   XEventController::AlterEventSession+5ab
   CStmtCreateEventSession::XretExecute+126
   CMsqlExecContext::ExecuteStmts<0,1>+8bd
   CMsqlExecContext::FExecute+a58
   CSQLSource::Execute+86c
   process_request+a57
   process_commands+4a3
   SOS_Task::Param::Execute+21e
   SOS_Scheduler::RunTask+ab
2. SOS_Task::PopWait+b1
   SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7a
   XE_Session::Commit+4ff
   XEventController::VLR_StartXESession::CommitAndRelease+81
   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
   CAutoMsqlXact::CommitNestedXact+bf
   FEventSessionStartup+2b9
   NotifyXEventMasterDbStarted+1bd
   NotifyMasterDatabaseReady+47
   StartUp::OpenDBsAndRecover+699
   StartUp::InitDBMS+aa
   SOS_Task::Param::Execute+21e
   SOS_Scheduler::RunTask+ab