Youtube API v3 error - Hangs on await searchListRequest.ExecuteAsync(); - winforms

Question

I've been playing around with the Youtube V3 API and i can't seem to get it to work in a windows form. I got the sample code to work, so I know that my API key works correctly, but when i try to convert it from a console app, the code hangs on this line,
var searchListResponse = await searchListRequest.ExecuteAsync();
I haven't been able to find anything relevant to this issue, there are no compile errors or run-time errors are being thrown. Any help would be greatly appreciated!
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Services;
using Google.Apis.Upload;
using Google.Apis.Util.Store;
using Google.Apis.YouTube.v3;
using Google.Apis.YouTube.v3.Data;
namespace MiddleManYTDL
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
MessageBox.Show("YouTube Data API: Search");
try
{
new Form1().Run().Wait();
}
catch (AggregateException exs)
{
foreach (var ex in exs.InnerExceptions)
{
MessageBox.Show("Error: " + ex.Message);
}
}
}
private async Task Run()
{
var youtubeService = new YouTubeService(new BaseClientService.Initializer()
{
ApiKey = "My API Key",
ApplicationName = this.GetType().ToString()
});
var searchListRequest = youtubeService.Search.List("snippet");
searchListRequest.Q = "Google"; // Replace with your search term.
searchListRequest.MaxResults = 10;
MessageBox.Show("This will Display");
// Call the search.list method to retrieve results matching the specified query term.
var searchListResponse = await searchListRequest.ExecuteAsync();
MessageBox.Show("This never gets executed");
List<string> videos = new List<string>();
List<string> channels = new List<string>();
List<string> playlists = new List<string>();
// Add each result to the appropriate list, and then display the lists of
// matching videos, channels, and playlists.
foreach (var searchResult in searchListResponse.Items)
{
switch (searchResult.Id.Kind)
{
case "youtube#video":
videos.Add(String.Format("{0} ({1})", searchResult.Snippet.Title,
searchResult.Id.VideoId));
break;
case "youtube#channel":
channels.Add(String.Format("{0} ({1})", searchResult.Snippet.Title,
searchResult.Id.ChannelId));
break;
case "youtube#playlist":
playlists.Add(String.Format("{0} ({1})", searchResult.Snippet.Title,
searchResult.Id.PlaylistId));
break;
}
}
MessageBox.Show(String.Format("Videos:\n{0}\n", string.Join("\n", videos)));
MessageBox.Show(String.Format("Channels:\n{0}\n", string.Join("\n", channels)));
MessageBox.Show(String.Format("Playlists:\n{0}\n", string.Join("\n", playlists)));
}
}
}

Answer 1

This has nothing to do with the YouTube API as such. Your problem is in the blocking Wait() call on the following line:
new Form1().Run().Wait();
What is happening is your code gets to Run() and executes the part of the method up to the await keyword synchronously (in your case - on the UI thread). Then, while the await is in progress, the execution returns to your Form.Load handler, which immediately hits the Wait() call and blocks the UI thread until the task returned by Run() has completed. At some point after that your awaited task inside Run() finishes and the async state machine attempts to execute the rest of the Run() method on the UI thread. Now you have Wait() blocking the UI thread while it's waiting for Run() to complete and Run() waiting for the UI thread to become available so that the remainder of the async method can be executed. Neither can make any progress. This deadlock scenario is very common whenever async/await methods are mixed with the blocking Wait() or Result calls.
There are two possible fixes:
Use async/await all the way (i.e. no blocking Wait() and Result calls up in the call hierarchy)
Rewrite your Run() method so that no UI elements are accessed after the await, and use ConfigureAwait(false) to prevent await from capturing, and subsequently posting back to the synchronization context installed on your UI thread (meaning that the part of your method following the await will execute on a thread pool thread).
Personally I'd go with option #1:
private async void Form1_Load(object sender, EventArgs e)
{
MessageBox.Show("YouTube Data API: Search");
try
{
await new Form1().Run();
}
catch (Exception ex)
{
// Exception dispatch is different with async/await,
// so you don't get the AggregateException - rather
// just the first exception which caused the task
// to fault.
MessageBox.Show("Error: " + ex.Message);
}
}
Here are some excellent blog posts which discuss the issue you are observing in detail:
http://blog.stephencleary.com/2012/07/dont-block-on-async-code.html
http://blogs.msdn.com/b/pfxteam/archive/2011/01/13/10115163.aspx