How can I set max_concurrent_streams #2868

shenghui0779 · 2024-08-08T03:53:35Z

shenghui0779
Aug 8, 2024

Summary

In Rust, using the hyper library, you can configure the max_concurrent_streams option to control the maximum number of concurrent streams in an HTTP/2 connection. This is particularly useful in high-concurrency environments to ensure efficient resource utilization and prevent server overload. In this guide, we'll explore how to set up and configure max_concurrent_streams in a hyper server, along with some practical examples and explanations.

What is max_concurrent_streams?
The max_concurrent_streams setting in HTTP/2 determines the maximum number of streams (requests/responses) that can be active concurrently on a single connection. This allows for multiplexing multiple requests over a single connection, improving the efficiency and performance of the application. By adjusting this parameter, you can optimize the resource usage on your server, ensuring that it can handle concurrent requests effectively without overwhelming the system.

Configuring max_concurrent_streams in Hyper

use hyper::service::{make_service_fn, service_fn};
use hyper::{Body, Request, Response, Server};
use hyper::server::conn::Http;
use tokio::net::TcpListener;
use std::convert::Infallible;
use std::net::SocketAddr;
use std::time::Duration;
use tower::ServiceBuilder;

async fn handle_request(_req: Request<Body>) -> Result<Response<Body>, hyper::Error> {
    Ok(Response::new(Body::from("Hello, World!")))
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
    // Define the address for the server to listen on
    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
    let listener = TcpListener::bind(addr).await?;

    // Create the Hyper service
    let make_svc = make_service_fn(|_conn| {
        async {
            Ok::<_, Infallible>(service_fn(handle_request))
        }
    });

    // Configure the HTTP/2 server with max_concurrent_streams
    let http = Http::new()
        .http2_max_concurrent_streams(128) // Set max concurrent streams to 128
        .http2_keep_alive_timeout(Duration::from_secs(20)) // Optional: Set keep-alive timeout
        .http2_keep_alive_interval(Duration::from_secs(10)) // Optional: Set keep-alive interval
        .http2_adaptive_window(true) // Enable adaptive window sizing
        .http2_initial_window_size(16_384); // Set initial window size

    // Start the Hyper server
    let server = Server::builder(hyper::server::accept::from_stream(
        async_stream::stream! {
            loop {
                let (stream, _) = listener.accept().await.unwrap();
                yield Ok::<_, hyper::Error>(stream);
            }
        }
    ))
    .http2_only(true) // Enable HTTP/2 only mode
    .http2_max_concurrent_streams(128) // Global max concurrent streams
    .serve(make_svc);

    println!("Server running at http://{}", addr);

    // Run the server
    server.await?;

    Ok(())
}

axum version

v0.7.5

jplatte · 2024-08-08T07:54:44Z

jplatte
Aug 8, 2024
Maintainer

Please elaborate. What is max_concurrent_streams?

0 replies

QuentinPerez · 2025-01-08T12:47:40Z

QuentinPerez
Jan 8, 2025

Please elaborate. What is max_concurrent_streams?
https://docs.rs/hyper/latest/hyper/client/conn/http2/struct.Builder.html#method.max_concurrent_streams

I’m not sure what the best way to approach this is, but it would be great to have more granular control over the HTTP/1 and HTTP/2 configuration.

In the current code, this would involve something like the following.
https://github.com/tokio-rs/axum/blob/main/axum/src/serve.rs#L314

                  #[cfg(feature = "http2")]
                    builder.http2().enable_connect_protocol();
                    // builder.http2().max_concurrent_streams(max)
                    let conn = builder.serve_connection_with_upgrades(io, hyper_service);

Once you confirm what is the best way to configure them, let me know. I’m eager to implement it, as I need it as well

1 reply

mladedav Jan 8, 2025
Collaborator

Currently, the best way to get more control over that configuration is to use axum-server. Or use hyper manually as is done in some examples.

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How can I set max_concurrent_streams #2868

shenghui0779 Aug 8, 2024

Summary

axum version

Replies: 2 comments · 1 reply

jplatte Aug 8, 2024 Maintainer

QuentinPerez Jan 8, 2025

mladedav Jan 8, 2025 Collaborator

shenghui0779
Aug 8, 2024

Replies: 2 comments 1 reply

jplatte
Aug 8, 2024
Maintainer

QuentinPerez
Jan 8, 2025

mladedav Jan 8, 2025
Collaborator