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PREEMPTIVE_OS_CRYPTIMPORTKEY

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Description:

This wait type is when a thread is calling the Windows CryptImportKey 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 422 in 2008 and 2008 R2, 470 in 2012, and 486 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:

If you see long waits for this wait type, have your infrastructure team investigate performance issues with servers that provide cryptographic services to the domain (for instance, the server for an Enterprise Key Management system).

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. Importing a key (in this case, while initializing TDS while starting the instance)
  2. Importing an asymmetric key (in this case, to decrypt a column value)
  3. Importing a key (in this case, as part of compiling a certificate-signed stored procedure)

And other similar 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
    CSECCryptoContext::ImportKey+166
    CSECPrivateKey::InitFromBytes+17e
    CSECCertificate::CreateNew+2f8
    CSECFallBackCert::Init+6f6
    CSECFallBackCert::InitInstance+174
    GetFallBackCertContext+10
    Ssl::InitializeListener+334
    SNIInitializeListener+550
    NodeListener::EndpointSet::Initialize+13b
    NodeListener::Initialize+4f
    SNIStartListening+7e
    TDSSNIClient::Init+230
    InitializeTDS+61
    FRunCommunicationsManager+4e
    CommunicationsManager+3c6
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab
  2. SOS_Task::PopWait+b1
    SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7c
    SOS_Task::AutoSwitchPreemptive::~AutoSwitchPreemptive+5d
    CSECCryptoContext::ImportKey+166
    CSECPublicKey::Init+f1
    CSECAsymmetricKey::InitFromMD+f6
    GetAsymKeyProperty+da
    SsvarAsymKeyPropI4Wstr+235
    CEsExec::GeneralEval4+e7
    CQScanFilterNew::GetRowHelper+55
    CQScanNLJoinNew::GetRowHelper+4f
    CQScanNLJoinNew::GetRowHelper+4f
    CQScanNLJoinNew::GetRowHelper+f4
    CQScanNLJoinNew::GetRowHelper+4f
    CQScanNLJoinNew::GetRowHelper+4f
    CQueryScan::GetRow+81
    CXStmtQuery::ErsqExecuteQuery+54a
    CXStmtSelect::XretExecute+2e7
    CMsqlExecContext::ExecuteStmts<1,1>+427
    CMsqlExecContext::FExecute+a43
    CSQLSource::Execute+86c
    process_request+a57
  3. SOS_Task::PopWait+b1
    SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7c
    SOS_Task::AutoSwitchPreemptive::~AutoSwitchPreemptive+5d
    CSECCryptoContext::ImportKey+166
    CSECPublicKey::Init+f1
    CSECCertificate::GetPublicKey+132
    CSECCryptoServices::VerifySignature+187
    CSECExecAsCompileServices::SetToObject+2ba
    CSQLSource::FCompile+1e7c
    CSQLSource::FCompWrapper+dd
    CSQLSource::Transform+445
    CSQLSource::Execute+401
    CStmtExecProc::XretLocalExec+25a
    CStmtExecProc::XretExecExecute+4e8
    CXStmtExecProc::XretExecute+38
    CMsqlExecContext::ExecuteStmts<1,1>+427
    CMsqlExecContext::FExecute+a43