REngine does not Dispose correctly

[aschwenker-insight]

I am using R.NET 1.9.0 with .NET Framework 4.8 and R 4.1.0.

Given the following code:

REngine.SetEnvironmentVariables();
using (var engine1 = REngine.GetInstance())
{
  //Do something
}

using(var engine2 = REngine.GetInstance())
{
  //Do something else
}

This code should execute successfully as engine1 is disposed before engine2 is created.

Instead the result is an InvalidOperationException with the message The single REngine instance has already been disposed of (i.e. shut down). Multiple engine restart is not possible.

This is occurring because the internal engine field within REngine is not being set to null during the Dispose(bool disposing) method.

Is this by design?

As a workaround, I am treating REngine as a singleton within my application but I believe I should be able to dispose and recreate it repeatedly.

My issue is occurring within an Azure Function that wraps an R library and loads an REngine for each request for isolation between calls.