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PREEMPTIVE_OS_GETFILEATTRIBUTES

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Description:

This wait type is when a thread is calling the Windows GetFileAttributes 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 453 in 2008 and 2008 R2, 501 in 2012, and 517 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. Getting the file attributes (in this case, while opening a log file as part of starting a database during instance startup)
  2. Getting the file attributes (in this case, while creating tempdb data files during instance startup)
  3. Getting the file attributes (in this case, while creating files during a BACKUP operation)

And many other similar call stacks.

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

  1. SOS_Task::PopWait+b1
    AutoSwitchPreemptive::~AutoSwitchPreemptive+95
    DBGetFileAttributesW+150
    FCB::Open+1b0
    FCB::OpenForStartup+18a
    FCB::Startup+2a
    FileMgr::StartLogFiles+27d
    FileMgr::StartupPreRecovery+7aa
    RecoveryUnit::PreRecovery+11c3
    StartupCoordinator::NotifyPhaseStart+3a
    DBTABLE::Startup+1045
    DBMgr::StartupDB+6c6
    DBMgr::StartDBsInParallel+511
    DBMgr::ParallelDbStartupEntryPoint+10f
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab
  2. SOS_Task::PopWait+b1
    AutoSwitchPreemptive::~AutoSwitchPreemptive+95
    DBGetFileAttributesW+150
    FCB::Open+1b0
    FCB::OpenForStartup+18a
    FCB::Startup+2a
    FCB::Startup+16a
    DBMgr::CreateAndFormatFiles+b47
    DBMgr::MakeTempdbFiles+b5c
    DBMgr::StartTempDB+181
    StartUp::StartModelAndTempdb+ba7
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab
  3. SOS_Task::PopWait+b1
    AutoSwitchPreemptive::~AutoSwitchPreemptive+95
    DBGetFileAttributesW+150
    CheckFileStreamReserved+a9
    BackupFileDesc::CheckBackupDevicePath+5b
    BackupFileList::CopyFiles+182
    BackupEntry::SetupObject+191
    BackupEntry::AllocateObject+1e9
    BackupEntry::BackupDatabase+1d0
    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