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PREEMPTIVE_FILESIZEGET

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Description:

This wait type is when a thread is calling the Windows GetFileSizeEx 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 450 in 2008 and 2008 R2, 498 in 2012, and 514 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 size of a data file (in this case, after running crash recovery on a database, which might have included some data file size changes)
  2. Getting the size of the primary data file (in this case, while creating the in-memory FCB (File Control Block) mapping of the primary file metadata while starting up a database)
  3. Getting the size of a log file (in this case, while creating the in-memory FCBs that map the metadata of the log files while starting up a database)

And other similar stacks.

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

  1. SOS_Task::PopWait+b1
    AutoSwitchPreemptive::~AutoSwitchPreemptive+95
    FCB::GetPhysicalFileSizeInPages+197
    FileMgr::FixupPostRedo+100
    RecoveryMgr::PhysicalCompletion+247
    RecoveryUnit::CompletePhysical+e9
    RecoveryUnit::PhaseEnd+a6
    StartupCoordinator::NotifyPhaseEnd+3b
    DBTABLE::Startup+1167
    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
    FCB::GetPhysicalFileSizeInPages+197
    FCB::Startup+54
    FCB::StartPrimaryFile+109
    DBTABLE::Startup+51b
    DBMgr::StartupDB+6c6
    DBMgr::StartDBsInParallel+511
    DBMgr::ParallelDbStartupEntryPoint+10f
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab
  3. SOS_Task::PopWait+b1
    AutoSwitchPreemptive::~AutoSwitchPreemptive+95
    FCB::GetPhysicalFileSizeInPages+197
    FCB::Startup+54
    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