ASYNC/AWAIT - To repro problems Tugberk experienced. VS2012 - .NET 4.5

gistfile1.txt

OK I have written this sample in VS 2012.

Here is output from trace:

Label: Before await |<Get>d__0.MoveNext() - Thread name: ''
 Label: Inside async |ValuesController.<DoWaitAsync>b__3() - Thread name: ''
 Label: Inside async after sleep |ValuesController.<DoWaitAsync>b__3() - Thread name: 'ValuesController.<DoWaitAsync>b__3()_ce0a3be5377f41fe8056b5fac2fd9464'
 Label: After await |<Get>d__0.MoveNext() - Thread name: ''
 Label: Beginning dowork |ValuesController.doWork() - Thread name: '<Get>d__0.MoveNext()_fc4664d4088d450e8140ad5b943ef1d3'
iisexpress.exe Information: 0 : doWork is running...System.Web.HttpContext
 Label: Ending dowork |ValuesController.doWork() - Thread name: '<Get>d__0.MoveNext()_fc4664d4088d450e8140ad5b943ef1d3'
 Label: After dowork |<Get>d__0.MoveNext() - Thread name: '<Get>d__0.MoveNext()_fc4664d4088d450e8140ad5b943ef1d3'

This proves that original thread exits just before wait. A new thread carries on after the await. So all-in-all 3 threads work in the span of that method.

ThreadExtensions.cs

using System.Diagnostics;

namespace System.Threading
{
    public static class ThreadNameTracingExtensions
    {
        /// <summary>
        /// if thread has a name, it leaves the name as it is. If it does not have a name,
        /// it sets the thread's name to the module.method
        /// It outputs as 
        /// </summary>
        /// <param name="thread"></param>
        public static void TraceName(this Thread thread)
        {
            TraceName(thread, string.Empty);
        }

        public static void TraceName(this Thread thread, string label)
        {
            var st = new StackTrace(new StackFrame(1));
            var methodBase = st.GetFrame(0).GetMethod();
            string frameName = string.Format("{0}.{1}()", methodBase.ReflectedType.Name, methodBase.Name);
            Trace.WriteLine(string.Format("{0}{1} - Thread name: '{2}'", 
                string.IsNullOrEmpty(label) ? "" : string.Format(" Label: {0} |", label),
                frameName, thread.Name));
            if (string.IsNullOrEmpty(thread.Name))
                thread.Name = frameName + "_" + Guid.NewGuid().ToString("N");

        }
    }
}

ValueController.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using System.Web.Http;

namespace MvcApplication1.Controllers
{
    public class ValuesController : ApiController
    {
        // GET api/values
        public async Task<IEnumerable<string>> Get()
        {

            Thread.CurrentThread.TraceName("Before await");
            await DoWaitAsync();
            Thread.CurrentThread.TraceName("After await");
            doWork();
            Thread.CurrentThread.TraceName("After dowork");
            return  new string[] { "value1", "value2" };

        }


        private Task DoWaitAsync()
        {
            return
                Task.Factory.StartNew(
                () => 
                {
                    Thread.CurrentThread.TraceName("Inside async");
                    Thread.Sleep(1000);
                    Thread.CurrentThread.TraceName("Inside async after sleep");
                });
        }

        public void doWork()
        {
            Thread.CurrentThread.TraceName("Beginning dowork");
            //Not null, runs perfectly fine
            var httpCtx = System.Web.HttpContext.Current;
            Trace.TraceInformation("doWork is running..." + httpCtx.ToString());
            Thread.CurrentThread.TraceName("Ending dowork");
        }

    }
}