HTTP request in pending status until MediatR notifications executed

Question

var response = SaveOrderInDB();
OrderCreatedEvent orderCreatedEvent = new OrderCreatedEvent(x, y, z);            
_requestRouter.Publish(orderCreatedEvent);
return response;

By MediatR docs the notifications is "Fire and forget" feature. I do not use await since I want to return immediately "response" object to client Angular app after notification was published. However when I put breakpoint in notification handler I see in Chrom dev tools that request still in pending status, waits for notification to finish.

 public Task Handle(OrderCreatedEvent notification, CancellationToken cancellationToken)
    {
        return Task.CompletedTask; // Breakpoint is here 
    }

How can I not wait for notifications to finish?

Answer 1

As mentioned in the comments, the breakpoint is preventing them from completing.

If you don't believe this, change your NotificationHandler to something like:

public async Task Handle(OrderCreatedEvent notification, CancellationToken cancellationToken)
{
    await Task.Delay(5000);

    Console.Write("Done."); //put a breakpoint here
}

Put a breakpoint on the Console.Write method, then run your application, and call your endpoint.

You'll see the response isn't pending, and after 5 seconds, your breakpoint is hit.
(or "Done." is written to the console if you didn't set a breakpoint)