VsTest is unable to load MKL Native Provider in UnitTest

Environment:

Unit Test project with target Framework .NET Framework 4.8 build in x64 with packages

MathNet.Numerics v5.0.0
MathNet.Numerics.Providers.MKL v5.0.0
MathNet.Numerics.MKL.Win-x64 v3.0.0

We have a Buildserver with Azure DevOps which runs the tests with VSTest@2

- task: VSTest@2 displayName: 'Run Tests' inputs: platform: '$(buildPlatform)' # x64 configuration: '$(buildConfiguration)' # Release searchFolder: '$(Pipeline.Workspace)' testSelector: 'testAssemblies' testAssemblyVer2: | \MyProject.Tests\bin\\MyProject.Tests.dll

The Problem:

In a UnitTest we have the line Control.UseNativeMKL();. Unfortunately since the update of MathNet this throws following exception on the buildserver, whereas it works fine locally in VisualStudio.

System.NotSupportedException : MKL Native Provider not found. ----> System.DllNotFoundException : Unable to load DLL 'libMathNetNumericsMKL': The specified module could not be found. (Exception from HRESULT: 0x8007007E) StackTrace: at MathNet.Numerics.Providers.MKL.MklProvider.Load(String hintPath, MklConsistency consistency, MklPrecision precision, MklAccuracy accuracy) at MathNet.Numerics.Providers.MKL.LinearAlgebra.MklLinearAlgebraProvider.InitializeVerify() at xx.Tests.xx.xxTests.TestSetup() in C:\agents_work\6\s\xx.Tests\xx\xx.cs:line 27 --DllNotFoundException at MathNet.Numerics.Providers.MKL.SafeNativeMethods.query_capability(Int32 capability) at MathNet.Numerics.Providers.MKL.MklProvider.Load(String hintPath, MklConsistency consistency, MklPrecision precision, MklAccuracy accuracy)

Investigation:

I have done some checks in the UnitTest.

Control.TryUseNativeMKL() returns false
Control.TryUseNative() returns false
Environment.CurrentDirectory returns my bin directory of the test project
In the bin directory of my test project the file 'runtimes\win-x64\native\libMathNetNumericsMKL.dll' exists
specify Control.NativeProviderPath = Path.Combine(Environment.CurrentDirectory, @"runtimes"); doesn't change the behavior
specify Control.NativeProviderPath = Path.Combine(Environment.CurrentDirectory, @"runtimes\win-x64\native\libMathNetNumericsMKL.dll"); doesn't change the behavior

When downgrading to MathNet.Numerics .v4.15.0 and MathNet.Numerics.MKL.Win-x64 v2.5.0 it works fine.

I would be very happy for any help or ideas. Thanks!

While trying to figure out the problem, the command MathNet.Numerics.Control.Describe() was quite helpful.

Which returns this Version 5.0.0 Built for .NET Framework 4.8 Linear Algebra Provider: **Managed** Fourier Transform Provider: **Managed** Sparse Solver Provider: **Managed** Max Degree of Parallelism: 6 Parallelize Elements: 300 Parallelize Order: 64 Check Distribution Parameters: True Thread-Safe RNGs: True Operating System: Microsoft Windows 10.0.19045 Operating System Architecture: X64 Framework: .NET Framework 4.8.9139.0 Process Architecture: X64 Processor Architecture: AMD64 Processor Identifier: Intel64 Family 6 Model 158 Stepping 10, GenuineIntel

I restarted the Buildserver machine by coincidence and it seems to have solved the problem.

So now I get this result and everything works again as expected.

Math.NET Numerics Configuration: Version 5.0.0 Built for .NET Framework 4.8 Linear Algebra Provider: Intel MKL (x64; revision 15; MKL 2022.0) Fourier Transform Provider: Intel MKL (x64; revision 15; MKL 2022.0) Sparse Solver Provider: Intel MKL (x64; revision 15; MKL 2022.0) Max Degree of Parallelism: 6 Parallelize Elements: 300 Parallelize Order: 64 Check Distribution Parameters: True Thread-Safe RNGs: True Operating System: Microsoft Windows 10.0.19045 Operating System Architecture: X64 Framework: .NET Framework 4.8.9139.0 Process Architecture: X64 Processor Architecture: AMD64 Processor Identifier: Intel64 Family 6 Model 158 Stepping 10, GenuineIntel

mathnet / mathnet-numerics