deadlock even after using ConfigureAwait(false) in Asp.Net flow

Question

I\'m hitting deadlock even after using ConfigureAwait(false), below is the sample code.

As per the sample http://blog.stephencleary.com/2012/02/async-a

Answer 1

I had the same problem. "ConfigureAwait(false)" can not always avoid dead lock.

public class HomeController : Controller
{
    public async Task Index()
    {
        // This works !
        ViewBag.Title = GetAsync().Result;

        // This cause deadlock even with "ConfigureAwait(false)" !
        ViewBag.Title = PingAsync().Result;

        return View();
    }

    public async Task GetAsync()
    {
        var uri = new Uri("http://www.google.com");
        return await new HttpClient().GetStringAsync(uri).ConfigureAwait(false);
    }

    public async Task PingAsync()
    {
        var pingResult = await new Ping().SendPingAsync("www.google.com", 3).ConfigureAwait(false);

        return pingResult.RoundtripTime.ToString();
    }
}

For the above code, "GetAsync()" works while "PingAsync()" doesn't.

But I found that if I wrap the async call into a new task, and wait this task, PingAsync() will work event without "ConfigureAwait(false)":

var task = Task.Run(() => PingAsync());
task.Wait();
ViewBag.Title = task.Result;

I don't know the reason, maybe someone can tell me the difference.