SSE subscription makes HotChocolate not being shutdown gracefully

[sunghwan2789]

Is there an existing issue for this?

• I have searched the existing issues

Product

Hot Chocolate

Describe the bug

If a SSE subscription alives, HotChocolate does not shutdown gracefully.

Sending Ctrl+C (SIGINT), Kestrel requests connections closed, but HotChocolate keeps connections open and RequestAborted is false.

Steps to reproduce

1. git clone https://github.com/sunghwan2789/hotchocolate.git --branch repro/sse-hangs --single-branch
2. dotnet run --project Server
3. Wait subscription started, and send Ctrl+C (SIGINT)

Relevant log output

No response

Additional Context?

No response

Version

14.0.0-p.9

[michaelstaib]

Thank you for reporting this.

[michaelstaib]

Can you create a repro?

[sunghwan2789]

Updated reproduction, thanks

[cmeeren]

Also being hit by this. This means we can't reliably update our API, because shutdown hangs whenever there's an active connection. Hoping this will get fixed soon!

[sunghwan2789]

Now, I think this is not a bug, but a user-level mistake: the resolver is responsible for completing the subscription on application stopping.

Kestrel also does not abort the client connection immediately:

using System.Runtime.CompilerServices;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpContextAccessor();

var app = builder.Build();

app.MapGet("/", Bar);

_ = DoSubscription(app.Lifetime.ApplicationStopped);

app.Run();

async Task DoSubscription(CancellationToken stopped) {
    var client = new HttpClient();

    while (!stopped.IsCancellationRequested) {
        try {
            await foreach (var response in client.GetFromJsonAsAsyncEnumerable<int>("http://localhost:5241/", stopped)) {
                Console.WriteLine(response);
            }
        } catch (Exception ex) {
            Console.WriteLine("retry... " + ex);
            await Task.Delay(1000, stopped);
        }
    }
}

async IAsyncEnumerable<int> Bar(IHttpContextAccessor contextAccessor, [EnumeratorCancellation] CancellationToken cancellationToken) {
    var context = contextAccessor.HttpContext;
    Console.WriteLine(context?.TraceIdentifier);
    var i = 0; 
    while (!cancellationToken.IsCancellationRequested) {
        yield return i++;
        await Task.Delay(1000, cancellationToken);
    }
}

[cmeeren]

the resolver is responsible for completing the subscription on application stopping

How can this be done? I can't find any information about that in the HC subscription docs.

[sunghwan2789]

Updated the reproduction and found that HC does not send a complete event and keep the connection open when an exception is thrown.

Now, I am sure it is a bug.