Use await Task.Delay(Timeout.Infinite, stoppingToken) in BackgroundService that is event-based

[marinaborozan3]

Is it better to use await Task.Delay(Timeout.Infinite, stoppingToken) at the end or await Task.Delay(1000, stoppingToken) in loop in ExecuteAsync method of BackgroundService that is event-based, meaning it creates some client in constructor and sets up events for the client, and it will be triggered by events, so it doesn't need a loop?

[Clockwork-Muse]

Neither.

First, something has a processing loop, even if your code never sees it directly. If you're working with a library for the event loop, probably there's a method you can wait on for "end of processing" status, or maybe their RunAsync (or whatever it's called) returns a task that can be waited on.
Second, the problem with cancelling like this is that it means you're going to have cancellation errors even when you try to shut down gracefully. Instead, it would be better to set up a TaskCompletionSource that can be waited on, and then when the signal is received to mark it completed. That also allows for explicit error signals to percolate out to the main process.

[marinaborozan3]

Of course something else has a processing loop. I am asking if there should be something awaited in ExecuteAsync method or it's not needed in this case.
'Second, the problem with cancelling like this is that it means you're going to have cancellation errors even when you try to shut down gracefully.' - can you please explain this?

[Clockwork-Muse]

ExecuteAsync only needs to return a (to be later completed) Task, you don't need to await anything. If your event processor already provides such a task, return that directly unless you need to do some other processing after it completes

can you please explain this?

All services generate logs, that should be monitored for problems. I had thought that this would mean that the TaskCanceledException from a canceled delay would be propagated, but if it's from the stopping token it looks like that's already gracefully handled.
That said, you still need a way to surface errors from your event loop code, so if there's a way to use a task from that it would be preferred.