LayerFactory causes QueuedTask.Run(...).Wait() to hang

Question

The Wait() method on the Task returned by QueuedTask.Run hangs when I try to use LayerFactory. If I use await, it works as expected. Am I doing something wrong? This works: protected override async void OnClick() { await QueuedTask.Run(()=> { LayerFactory.CreateGroupLayer(MapView.Active.Map, 0, "group layer"); Debug.Print("layer created"); }); Debug.Print("done"); }‍‍‍‍‍‍‍‍ But this hangs: protected override void OnClick() { QueuedTask.Run(()=> { LayerFactory.CreateGroupLayer(MapView.Active.Map, 0, "group layer"); Debug.Print("layer created"); }).Wait(); Debug.Print("done"); }‍‍‍‍‍‍‍‍ This works (suggesting LayerFactory is clogging the plumbing): protected override void OnClick() { QueuedTask.Run(() => { for (int i = 0; i < 5; i++) { Debug.Print("Sleeping " + i); System.Threading.Thread.Sleep(1000); } Debug.Print("waking"); }).Wait(); Debug.Print("done"); } ‍‍‍‍‍‍‍‍‍‍‍‍

Wolf · Answer

Hi Kirk,

Your question is probably best answered in a Microsoft c# Forum because the answer is found in the way Microsoft's Task-based Asynchronous Pattern (TAP) works.  In general "Wait" will synchronously block until the task completes. So the current thread is literally blocked waiting for the task to complete. As a general rule, you should always use 'await' in the context of ArcGIS Pro SDK asynchronous coding.

- Wolf