PREEMPTIVE_OS_REPORTEVENT

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Description:

This wait type is when a thread is calling the Windows ReportEvent 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 494 in 2008 and 2008 R2, 542 in 2012, and 558 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. Printing to the event log (in this case, reporting the progress of rolling back transactions during crash recovery of a database during instance startup)
2. Printing to the event log (in this case, reporting the time of the last clean consistency check for a database during instance startup)
3. Printing to the event log (in this case, reporting the success of a BACKUP DATABASE operation)

And many other similar call stacks.

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

1. SOS_Task::PopWait+b1
   SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7c
   SOS_Task::AutoSwitchPreemptive::~AutoSwitchPreemptive+5d
   CErrorReportingManager::SendErrorToEventLog+5fa
   CErrorReportingManager::CwchFormatAndPrint+d91
   scierrlog+79
   RecoveryMgr::RollbackRemaining+19c
   RecoveryUnit::DoRollbackRecovery+19
   RecoveryUnit::DoAsyncRecovery+5ec
   DBMgr::RunRollbackRecovery+2ff
   DBMgr::StartDBsInParallel+51b
   DBMgr::ParallelDbStartupEntryPoint+10f
   SOS_Task::Param::Execute+21e
   SOS_Scheduler::RunTask+ab
2. OS_Task::PopWait+b1
   SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7c
   SOS_Task::AutoSwitchPreemptive::~AutoSwitchPreemptive+5d
   CErrorReportingManager::SendErrorToEventLog+5fa
   CErrorReportingManager::CwchFormatAndPrint+d91
   scierrlog+79
   DBTABLE::LogLastKnownGoodCheckDB+b7
   DBTABLE::Startup+17ff
   DBMgr::StartupDB+6c6
   DBMgr::StartDBsInParallel+511
   DBMgr::ParallelDbStartupEntryPoint+10f
   SOS_Task::Param::Execute+21e
   SOS_Scheduler::RunTask+ab
3. SOS_Task::PopWait+b1
   SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7c
   SOS_Task::AutoSwitchPreemptive::~AutoSwitchPreemptive+5d
   CErrorReportingManager::SendErrorToEventLog+5fa
   CErrorReportingManager::CwchFormatAndPrint+d91
   bkupierrlog+79
   BackupOperation::ReportSuccess+367
   BackupEntry::BackupDatabase+43f
   CStmtDumpDb::XretExecute+ef
   CMsqlExecContext::ExecuteStmts<1,1>+427
   CMsqlExecContext::FExecute+a43
   CSQLSource::Execute+86c
   process_request+a57
   process_commands+4a3
   SOS_Task::Param::Execute+21e
   SOS_Scheduler::RunTask+ab