(Republishing, or using this info in a commercial product/website, is prohibited without permission. All other uses are permitted. If in doubt, please ask.)

PREEMPTIVE_OS_DECRYPTMESSAGE

(Back to main page…)

Description:

This wait type is when a thread is calling the Windows DecryptMessage function.

(Books Online description: N/A)

Questions/comments on this wait type? Click here to send Paul an email, especially if you have any information to add to this topic.

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 369 in 2008 and 2008 R2, 416 in 2012, and 432 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. Decrypting an I/O completion message
  2. Decrypting a TDS message from a client

And other similar stacks

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

  1. SOS_Task::PopWait+b1
    SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7c
    Ssl::Decrypt+23a
    CryptoBase::DecryptLoop+42
    CryptoBase::ReadDone+3d5
    SNIReadDone+bc
    SOS_Node::ListenOnIOCompletionPort+32a
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab
  2. SOS_Task::PopWait+b1
    SOS_ExternalAutoWait::~SOS_ExternalAutoWait+7c
    Ssl::Decrypt+23a
    CryptoBase::DecryptLoop+42
    CryptoBase::ReadAsync+2fe
    SNIReadAsync+8e
    TDSSNIClient::ReadAsync+15f
    TDSSNIClient::AddSSLProviderHandler+48c
    SNIProcessAddProviderOnWorker+122
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+ab