`await HttpClient.GetAsync()` failing silently - DNX command line app

Question

The following fails silently on the indicated line.

using (var ht = new HttpClient())
{
    var r = await ht.GetAsync(RootUrl + Id.ToString()); <-----
    Page = await r.Content.ReadAsStringAsync();
}

No exception, no error, no nothing. Execution just stops, doesn't hit a breakpoint on the next line, and the app exits. Surrounding in a try/catch doesn't trigger a catch either.

Running as a DNX .xproj commandline app.

Same behavior with both coreclr and full. Started both through VS, and DNX command line.

What the heck is going on?

Project.json is as follows:

{
    "version": "1.0.0-*",
    "description": "Scrapers Console Application",
    "authors": [ "Kaelan" ],
    "tags": [ "" ],
    "projectUrl": "",
    "licenseUrl": "",

    "dependencies": {

        "System.Net.Http": "4.0.0-*",
        "HtmlAgilityPack": "1.4.9"
    },

  "commands": {
    "Scrapers": "Scrapers"
  },

  "frameworks": {
    "dnx451": { }
    }
}

Edit: Full code i'm working with. Took the chunk of the actual project to test, (maintains the same issue).

public class Program
{
    const string RootUrl = "<-snipped->";
    public async void Main(string[] args)
    {
        var Id = 244;

        var Page = "";

        using (var ht = new HttpClient())
        {
            var r = await ht.GetAsync(RootUrl + Id.ToString());
            Debug.Write(r.StatusCode + " on page: " + Id.ToString());

            Page = await r.Content.ReadAsStringAsync();
        }

        Console.ReadLine();
    }
}

Shouldn't there be a compiler warning for async Main? Btw, the repo did point to the solution. See the answer. — usr, Aug 29 '15 at 22:48
@usr: This isn't a normal console Main. It's a DNX-hosted console, with an instance (not static) `Main` method, which actually allows `async Task Main` methods. So the compilers don't treat it special at all (yet). I have a [blog post exploring this a bit](http://blog.stephencleary.com/2015/03/async-console-apps-on-net-coreclr.html). — Stephen Cleary, Aug 29 '15 at 23:02
@StephenCleary did you relocate the blog? I have subscribed previously but I was not notified of the recent articles you posted. My Feedly also doesn't seem to know the blog. — usr, Aug 29 '15 at 23:04
@usr: I went to [feedburner](http://feeds.feedburner.com/NitoPrograms) quite a while ago, but the [original location](http://blog.stephencleary.com/feed.xml) should have stayed the same. The blog transition wasn't quite seamless, sorry! — Stephen Cleary, Aug 29 '15 at 23:10

score 3 · Accepted Answer · answered Aug 29 '15 at 22:38

3

You should avoid async void.

Change the return type to the appropriate asynchronous return type for methods without result values: Task.

answered Aug 29 '15 at 22:38

Stephen Cleary

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1

Good advice (and could be a good comment), but in which way does this post answer the question? – Eser Aug 29 '15 at 22:39
2

@Eser: It prevents the dnx console app from exiting until the HTTP request completes. As such, this is an answer, not a comment. – Stephen Cleary Aug 29 '15 at 22:40
I... actually never did think to check that. Thanks. – Kaelan Fouwels Aug 29 '15 at 22:59

`await HttpClient.GetAsync()` failing silently - DNX command line app

1 Answers1