Promise completions should be executed on the thread pool

src/Discord.Net/Audio/AudioClient.cs

@@ -230,7 +230,7 @@ namespace Discord.Audio
                             _secretKey = data.SecretKey;
                             await ApiClient.SendSetSpeaking(true).ConfigureAwait(false);
 
-                            _connectTask.TrySetResult(true);
+                            var _ = _connectTask.TrySetResultAsync(true);
                         }
                         break;
                     case VoiceOpCode.HeartbeatAck:

src/Discord.Net/DiscordSocketClient.cs

@@ -531,7 +531,7 @@ namespace Discord
                                     await _readyEvent.InvokeAsync().ConfigureAwait(false);
                                     await SyncGuildsAsync().ConfigureAwait(false);
                                     
-                                    _connectTask.TrySetResult(true); //Signal the .Connect() call to complete
+                                    var _ = Task.Run(() => _connectTask.TrySetResult(true)); //Signal the .Connect() call to complete
                                     await _gatewayLogger.InfoAsync("Ready").ConfigureAwait(false);
                                 }
                                 break;

src/Discord.Net/Entities/WebSocket/CachedGuild.cs

@@ -96,9 +96,9 @@ namespace Discord
                     AddUser(model.Members[i], dataStore, members);
                 if (Discord.ApiClient.AuthTokenType != TokenType.User)
                 {
-                    _syncPromise.TrySetResult(true);
+                    var _ = _syncPromise.TrySetResultAsync(true);
                     if (!model.Large)
-                        _downloaderPromise.TrySetResult(true);
+                        _ = _downloaderPromise.TrySetResultAsync(true);
                 }
 
                 for (int i = 0; i < model.Presences.Length; i++)
@@ -122,9 +122,9 @@ namespace Discord
                 DownloadedMemberCount = 0;
                 for (int i = 0; i < model.Members.Length; i++)
                     AddUser(model.Members[i], dataStore, members);
-                _syncPromise.TrySetResult(true);
+                var _ = _syncPromise.TrySetResultAsync(true);
                 if (!model.Large)
-                    _downloaderPromise.TrySetResult(true);
+                    _ = _downloaderPromise.TrySetResultAsync(true);
 
                 for (int i = 0; i < model.Presences.Length; i++)
                     AddOrUpdateUser(model.Presences[i], dataStore, members);
@@ -233,7 +233,7 @@ namespace Discord
         }
         public void CompleteDownloadMembers()
         {
-            _downloaderPromise.TrySetResult(true);
+            _downloaderPromise.TrySetResultAsync(true);
         }
 
         public VoiceState AddOrUpdateVoiceState(VoiceStateModel model, DataStore dataStore, ConcurrentDictionary<ulong, VoiceState> voiceStates = null)

src/Discord.Net/Extensions/TaskCompletionSourceExtensions.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Threading.Tasks;
+
+namespace Discord
+{
+    internal static class TaskCompletionSourceExtensions
+    {
+        public static Task SetResultAsync<T>(this TaskCompletionSource<T> source, T result)
+            => Task.Run(() => source.SetResult(result));
+        public static Task<bool> TrySetResultAsync<T>(this TaskCompletionSource<T> source, T result)
+            => Task.Run(() => source.TrySetResult(result));
+
+        public static Task SetExceptionAsync<T>(this TaskCompletionSource<T> source, Exception ex)
+            => Task.Run(() => source.SetException(ex));
+        public static Task<bool> TrySetExceptionAsync<T>(this TaskCompletionSource<T> source, Exception ex)
+            => Task.Run(() => source.TrySetException(ex));
+
+        public static Task SetCanceledAsync<T>(this TaskCompletionSource<T> source)
+            => Task.Run(() => source.SetCanceled());
+        public static Task<bool> TrySetCanceledAsync<T>(this TaskCompletionSource<T> source)
+            => Task.Run(() => source.TrySetCanceled());
+    }
+}

src/Discord.Net/Net/Queue/RequestQueueBucket.cs

@@ -141,7 +141,7 @@ namespace Discord.Net.Queue
         private async Task QueueResumeAsync(TaskCompletionSource<byte> resumeNotifier, int millis)
         {
             await Task.Delay(millis).ConfigureAwait(false);
-            resumeNotifier.SetResult(0);
+            resumeNotifier.TrySetResultAsync<byte>(0);
         }
 
         private async Task EnterAsync(int? endTick)