Problem while loading third party dll in runtime using System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyName

Question

In my .NET Core 6.0 WebAPI project, I am trying to load third party dlls using System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyName.

Frequently I see while loading the third party dlls it gets unloaded when my WebAPI is idle for sometime. When I restart IIS it works fine. What could be the possibilities of unloading dll frequently?

Is this a known issue using System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyName()? If so, how can I work around it?

Alternatively, is there any DLL other than System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyName I can use?

I am using this piece of code to load the assembly file:

public Assembly LoadPlugin(string assemblyPath)
{
    CustomAssemblyLoadContext loadContext = new CustomAssemblyLoadContext(assemblyPath);
    return loadContext.LoadFromAssemblyName(new AssemblyName(Path.GetFileNameWithoutExtension(assemblyPath)));
}

Answer 1

Not sure how do you custom the AssemblyLoadContext, but by default AssemblyLoadContext configuration, it contains isCollectible which is false and it prevents unloading:

var assemblyLoadContext = new AssemblyLoadContext(null, isCollectible: false);

If the default setting is still not working, you can try to ensure actively uses types or objects from the loaded assembly:

var assembly = System.Runtime.Loader.AssemblyLoadContext.Default.LoadFromAssemblyName(new AssemblyName("YourAssemblyName"));

// Create an instance of a type from the assembly to hold a reference
var instance = assembly.CreateInstance("Namespace.ClassName");