handle tokio delay_for block

[daiguadaidai]

verstion
actix-web = "3"
tokio = { version = "0.2", features = ["full"] }

code

use actix_web::{get, web, App, HttpResponse, HttpServer, Responder};

async fn handle_hello() -> impl Responder {
    HttpResponse::Ok().body("get api hello!")
}

#[get("/world")]
async fn handle_world() -> impl Responder {
    println!("tokio sleep start");
    tokio::time::delay_for(tokio::time::Duration::from_secs(5)).await;
    println!("tokio sleep end");
    HttpResponse::Ok().body("get api world!")
}

fn config(cfg: &mut web::ServiceConfig) {
    cfg.service(web::resource("/hello").route(web::get().to(handle_hello)))
        .service(handle_world);
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    HttpServer::new(|| App::new().service(web::scope("/api").configure(config)))
        .bind("127.0.0.1:8080")?
        .workers(4)
        .run()
        .await
}

client request

session1:
curl http://127.0.0.1:8080/api/world

session2:
curl http://127.0.0.1:8080/api/world

server output

tokio sleep start
tokio sleep end
tokio sleep start
tokio sleep end

I think it should output

tokio sleep start
tokio sleep start
tokio sleep end
tokio sleep end

[fakeshadow]

use std::{
    io::{Read, Write},
    net::TcpStream,
};

use actix_web::{get, web, App, HttpResponse, HttpServer, Responder};

async fn handle_hello() -> impl Responder {
    HttpResponse::Ok().body("get api hello!")
}

#[get("/world")]
async fn handle_world() -> impl Responder {
    println!("tokio sleep start");
    tokio::time::delay_for(tokio::time::Duration::from_secs(5)).await;
    println!("tokio sleep end");
    HttpResponse::Ok().body("get api world!")
}

fn config(cfg: &mut web::ServiceConfig) {
    cfg.service(web::resource("/hello").route(web::get().to(handle_hello)))
        .service(handle_world);
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    let server = HttpServer::new(|| App::new().service(web::scope("/api").configure(config)))
        .bind("127.0.0.1:8080")?
        .workers(4)
        .run();

    let req = "GET /api/world HTTP/1.1\r\n\r\n";

    (0..32)
        .map(|_| {
            std::thread::spawn(move || {
                let mut stream = TcpStream::connect("127.0.0.1:8080").unwrap();
                stream.write(req.as_ref()).unwrap();
                let mut buf = [0u8; 1024];
                let n = stream.read(&mut buf).unwrap();
                println!("response is {:?}", String::from_utf8_lossy(&buf[..n]));
            })
        })
        .collect::<Vec<_>>()
        .into_iter()
        .for_each(|h| {
            h.join().unwrap();
        });

    server.stop(false).await;

    Ok(())
}

Your curl is most likely reusing a single TCP connection so they are queued up. You need a better tool for testing concurrency and/or parallel.

[daiguadaidai]

thanks.
I use two diff tool (curl, postman).
output:

tokio sleep start
tokio sleep start
tokio sleep end
tokio sleep end