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