SignalR Hub request 1 must complete before hub request 2 can run from a single client

[mrrobrob]

A single client calls a long running hub request, it also needs to call some much faster requests, however the faster requests don't seem to start until the slow request has completed.

To Reproduce

I'm using ASP.NET Core 2.2 and SignalR 1.1.

Hub code is very simple:

   public class TestHub: Hub
    {
        Random r = new Random();
        public async Task SlowTask()
        {
            await Task.Delay(5000);
            await Clients.Caller.SendAsync("slowNumber", r.Next());
        }

        public async Task FastTask()
        {
            await Task.Delay(5);
            await Clients.Caller.SendAsync("fastNumber", r.Next());
        }
    }

Using a single hub conection call the SlowTask, then call the FastTask, fastNumber is not sent back until after SlowTask completes.

Expected behavior

I'd expect FastTask to always finish quickly.

[davidfowl]

Duplicate of #5351