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