C#•3w ago

✅ Is it worth to use stackalloc here?

Hey, I have this:

[HttpGet("stream")]
public async Task StreamHeartbeatAsync(CancellationToken cancellationToken)
{
    Response.Headers.Append("Content-Type", "text/event-stream");
    Response.Headers.Append("Cache-Control", "no-cache");
    Response.Headers.Append("Connection", "keep-alive");

    while(!cancellationToken.IsCancellationRequested)
    {
        var sseEvent = new SseEvent<object>
        {
            Action = SseAction.Heartbeat,
            Timestamp = DateTime.UtcNow
        };

        await Response.WriteAsJsonAsync(sseEvent, cancellationToken);
        await Response.Body.FlushAsync(cancellationToken);

        await Task.Delay(sseSettings.Timeout, cancellationToken);
    }
}

public sealed class SseEvent<T>
{
    public required DateTime Timestamp { get; set; }
    public required SseAction Action { get; set; }
    public string? Store { get; set; }
    public string? Identity { get; set; }
    public T? Data { get; set; }
}

[HttpGet("stream")]
public async Task StreamHeartbeatAsync(CancellationToken cancellationToken)
{
    Response.Headers.Append("Content-Type", "text/event-stream");
    Response.Headers.Append("Cache-Control", "no-cache");
    Response.Headers.Append("Connection", "keep-alive");

    while(!cancellationToken.IsCancellationRequested)
    {
        var sseEvent = new SseEvent<object>
        {
            Action = SseAction.Heartbeat,
            Timestamp = DateTime.UtcNow
        };

        await Response.WriteAsJsonAsync(sseEvent, cancellationToken);
        await Response.Body.FlushAsync(cancellationToken);

        await Task.Delay(sseSettings.Timeout, cancellationToken);
    }
}

public sealed class SseEvent<T>
{
    public required DateTime Timestamp { get; set; }
    public required SseAction Action { get; set; }
    public string? Store { get; set; }
    public string? Identity { get; set; }
    public T? Data { get; set; }
}

I think it is not good to create sseEvent every second without any memory clean. Is it worth to use stackalloc here?

22 Replies

ero•3w ago

var sseEvent = new SseEvent<object>
{
    Action = SseAction.Heartbeat
};

while (!cancellationToken.IsCancellationRequested)
{
  sseEvent.Timestamp = DateTime.UtcNow;

  // ...
}

var sseEvent = new SseEvent<object>
{
    Action = SseAction.Heartbeat
};

while (!cancellationToken.IsCancellationRequested)
{
  sseEvent.Timestamp = DateTime.UtcNow;

  // ...
}

would this not work?

jcotton42•3w ago

Classes cannot be stackalloced.

ero•3w ago

they can be in .net 9

jcotton42•3w ago

Link? Iirc there’s escape analysis coming, but that’s something the JIT may do as an optimization.

ero•3w ago

i must've made that fact up in my head somehow i swear i was very sure it was true

SWEETPONYOP•3w ago

yeah, it was just an example and I missed this but anyway.. I can change class to struct or record struct for example is it worth it?

ero•3w ago

you'll have to benchmark that yourself. i wouldn't think it's really worth it, since it would be a fairly large struct

SWEETPONYOP•3w ago

let's imagine we should somehow optimize objects creation. How can we do it?

ero•3w ago

why should you optimize? have you checked that this is a bottleneck at all? there are likely many other aspects that are much more prone to causing performance degradation besides instantiating a lot of classes...

cap5lut•3w ago

because its async, u probably will have bad times with such a big struct anyway, if u pass value types around u are copying the data over. since its async, u cant utilize refs in any way either, so it will be most likely slower. if u want to reduce allocations, the better fit here would be most likely object pooling, which comes with its own down sides

ero•3w ago

(unless you use c# 13)

cap5lut•3w ago

u are missing the point, u would have to pass the ref to the awaited async method, which wont happen to be allowed like ... ever

ero•3w ago

mhhh right

Unknown User•3w ago

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SWEETPONYOP•3w ago

hm yes, sse is good for this things actually I don't need signalr signalr can choose websockets, sse etc I just need sse

cap5lut•3w ago

if its just server->client i wouldnt bother with websockets/signalr either

SWEETPONYOP•3w ago

ws is good but i need sse here, thats why I use text/event-stream anyway thanks for helping

Unknown User•3w ago

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SWEETPONYOP•3w ago

https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events read docs

MDN Web Docs

Using server-sent events - Web APIs | MDN

Developing a web application that uses server-sent events is straightforward. You'll need a bit of code on the server to stream events to the front-end, but the client side code works almost identically to websockets in part of handling incoming events. This is a one-way connection, so you can't send events from a client to a server.

SWEETPONYOP•3w ago

and https://www.strathweb.com/2024/07/built-in-support-for-server-sent-events-in-net-9/ I don't need signalr in my opinion why should I install the whole library just for heartbeat I can do it manually also use signalr and force it to use just sse is weird

Omnissiah•3w ago

you would have to split by \n and add a data: for each line

Unknown User•3w ago

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✅ Is it worth to use stackalloc here?