using System;

using System.Threading;

using System.Threading.Tasks;

using System.Runtime.CompilerServices;

public class Program

{

    public static void Main()

    {

        var t = new Thread(CallPerform);

        t.Start();

        t.Join();

        Console.WriteLine("Finished");

    }

    public static void CallPerform()

    {

        PrintThreadId();                

        Perform().Wait();

        PrintThreadId();

    }

    public static async Task Perform()

    {

        PrintThreadId();

        await Task.Delay(200).ConfigureAwait(false);

        PrintThreadId();

    }

    public static void PrintThreadId([CallerLineNumber] int lineNumber = 0)

    {

        Console.WriteLine("Line: {0} Thread-Id: {1}", lineNumber, Thread.CurrentThread.ManagedThreadId);        

    }

}