I quite like async/await except that it's annoyingly easy to produce a deadlock, and given a snippet, it's not obvious that such a deadlock should occur.

Ironically it is essentially the event loop which causes the deadlock in C#.

Depending on what framework/runtime you're in .NET will schedule the await continuation on something called a "SynchronizationContext" which has ~3 different forms but it's basically an event loop/message loop which queues up each continuation on the original thread.

The problem occurs when you use .Wait() or .Result instead of 'await'. This causes the function to spin waiting for the Task to finish, which of course it never will if it has a continuation trying to dispatch into that same event loop.

This problem doesn't really happen at all under some circumstances, such as if the async chain starts on a background thread, or in .net core where they've removed the SynchronizationContext, hence no event loop, hence no problems.

Do you have an example? I’ve never seen a deadlock in Js. I’m trying to think of how it’s even possible? Async/await is just super around promises anyway.

Oops, should've specified C# specifically, in which deadlock has become notorious. I don't think there's anything wrong with async/await per se. It looks to me like the linearity of js engine event loops wouldn't produce the same problem.

Ohh gotcha, shoulda picked up on the context :)