using System;

using System.Threading;

using System.Threading.Tasks;

public class Program

{

    static AsyncLocal<string> _asyncLocalString = new AsyncLocal<string>();

​

    static ThreadLocal<string> _threadLocalString = new ThreadLocal<string>();

​

    static async Task AsyncMethodA()

    {

        // Start multiple async method calls, with different AsyncLocal values.

        // We also set ThreadLocal values, to demonstrate how the two mechanisms differ.

        _asyncLocalString.Value = "Value 1";

        _threadLocalString.Value = "Value 1";

        var t1 = AsyncMethodB("Value 1");

​

        _asyncLocalString.Value = "Value 2";

        _threadLocalString.Value = "Value 2";

        var t2 = AsyncMethodB("Value 2");

​

        // Await both calls

        await t1;

        Console.WriteLine("Awaited AsyncMethodB 1.");

        Console.WriteLine("   AsyncLocal value is '{0}', ThreadLocal value is '{1}'", 

                          _asyncLocalString.Value, _threadLocalString.Value);

        await t2;

        Console.WriteLine("Awaited AsyncMethodB 2.");

        Console.WriteLine("   AsyncLocal value is '{0}', ThreadLocal value is '{1}'", 

                          _asyncLocalString.Value, _threadLocalString.Value);

     }

​

    static async Task AsyncMethodB(string expectedValue)

    {

        Console.WriteLine("Entering AsyncMethodB.");

        Console.WriteLine("   Expected '{0}', AsyncLocal value is '{1}', ThreadLocal value is '{2}'", 

                          expectedValue, _asyncLocalString.Value, _threadLocalString.Value);

        await Task.Delay(100);

        _asyncLocalString.Value = expectedValue + " - internal";

        Console.WriteLine("Exiting AsyncMethodB.");

        Console.WriteLine("   Expected '{0}', got '{1}', ThreadLocal value is '{2}'", 

                          expectedValue, _asyncLocalString.Value, _threadLocalString.Value);

    }

​

    public static void Main()

    {

        AsyncMethodA().Wait();

    }

}