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PREEMPTIVE_OS_DELETEFILE

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Description:

This wait type is when a thread is calling the Windows DeleteFile 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 447 in 2008 and 2008 R2, 495 in 2012, and 511 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 file (in this case, while removing old trace files while initializing C2-compliant tracing during instance startup)
  2. Deleting a file (in this case, as part of a DROP DATABASE operation)
  3. Deleting a file (in this case, while removing the backup checkpoint file from when the previous backup operation was interrupted)

And other similar stacks.

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

  1. SOS_Task::PopWait+b1
    SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7c
    CTrcFile::FDeleteOldTraceFile+1de
    CTrace::DeleteOldTraceFile+25
    CTraceFileIoProvider::OpenNextFile+2da
    CTraceFileIoProvider::Init+1a3
    CTraceFileIoProvider::CreateTraceIoProvider+91
    CTrace::Init+180
    CTraceController::CreateTrace+5f0
    CTraceController::SetupDefaultTrace+4ca
    InitializeC2Tracing+12b
    NotifyMasterDatabaseReady+4f
    StartUp::OpenDBsAndRecover+699
    StartUp::InitDBMS+aa
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab
  2. SOS_Task::PopWait+b1
    AutoSwitchPreemptive::~AutoSwitchPreemptive+95
    DBDeleteFileW+c0
    AsynchronousDiskAction::DoDeleteFile+87
    AsynchronousDiskAction::ExecuteDeferredAction+e2
    AsynchronousDiskPool::PerformActionsSerially+61
    AsynchronousDiskPool::WaitUntilDoneOrTimeout+71
    AsynchronousDiskPool::WaitUntilDone+c
    AsynchronousDiskPool::WaitUntilDoneNoThrow+40
    NotifyEndDropDatabase::HandleEvent+12b
    XactRM::FireNotificationsInternal+cf
    XactRM::SinglePhaseCommit+4e1
    XactRM::CommitInternal+472
    FullXactImp::Commit+33f
    CMsqlXactInternalReadWrite::Commit+19
    CMsqlXactImp::Commit+1d6
    CAutoMsqlXact::CommitNestedXact+bf
    CStmtDropDB::XretExecute+d97
    CMsqlExecContext::ExecuteStmts<0,1>+8bd
    CMsqlExecContext::FExecute+a58
    CSQLSource::Execute+86c
    process_request+a57
  3. SOS_Task::PopWait+b1
    AutoSwitchPreemptive::~AutoSwitchPreemptive+95
    DBDeleteFileW+c0
    BackupDeleteFile+14
    CheckpointableOperation::DeleteCheckpointFile+62
    BackupOperation::DeleteRestoreCheckpointFileWhenRestoreStarts+b0
    BackupOperation::Restore+431
    BackupEntry::RestoreLog+177
    CStmtLoadXact::XretExecute+105
    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