使用 Hyper 同时获取多个 URL

Question

我正在尝试调整 Hyper basic client example 以同时获取多个 URL。

这是我目前拥有的代码：

extern crate futures;
extern crate hyper;
extern crate tokio_core;

use std::io::{self, Write};
use std::iter;
use futures::{Future, Stream};
use hyper::Client;
use tokio_core::reactor::Core;

fn get_url() {
    let mut core = Core::new().unwrap();
    let client = Client::new(&core.handle());
    let uris: Vec<_> = iter::repeat("http://httpbin.org/ip".parse().unwrap()).take(50).collect();
    for uri in uris {
        let work = client.get(uri).and_then(|res| {
            println!("Response: {}", res.status());

            res.body().for_each(|chunk| {
                io::stdout()
                    .write_all(&chunk)
                    .map_err(From::from)
            })
        });
        core.run(work).unwrap();
    }
}

fn main() {
    get_url();
}

它似乎没有同时执行（需要很长时间才能完成），我是否以错误的方式将工作交给核心？

Answer 1

我是否以错误的方式将工作交给核心？

是的，您正在向 Tokio 发出一个请求，并要求它在开始下一个请求之前完成。您采用了异步代码并强制它是顺序的。

你需要给反应堆一个单一的未来，它将执行不同种类的并发工作。

超 0.14

use futures::prelude::*;
use hyper::{body, client::Client};
use std::{
    io::{self, Write},
    iter,
};
use tokio;

const N_CONCURRENT: usize = 1;

#[tokio::main]
async fn main() {
    let client = Client::new();

    let uri = "http://httpbin.org/ip".parse().unwrap();
    let uris = iter::repeat(uri).take(50);

    stream::iter(uris)
        .map(move |uri| client.get(uri))
        .buffer_unordered(N_CONCURRENT)
        .then(|res| async {
            let res = res.expect("Error making request: {}");
            println!("Response: {}", res.status());

            body::to_bytes(res).await.expect("Error reading body")
        })
        .for_each(|body| async move {
            io::stdout().write_all(&body).expect("Error writing body");
        })
        .await;
}

N_CONCURRENT 设置为 1：

real    1.119   1119085us
user    0.012   12021us
sys     0.011   11459us

并设置为 10：

real    0.216   216285us
user    0.014   13596us
sys     0.021   20640us

Cargo.toml

[dependencies]
futures = "0.3.17"
hyper = { version = "0.14.13", features = ["client", "http1", "tcp"] }
tokio = { version = "1.12.0", features = ["full"] }

超 0.12

use futures::{stream, Future, Stream}; // 0.1.25
use hyper::Client; // 0.12.23
use std::{
    io::{self, Write},
    iter,
};
use tokio; // 0.1.15

const N_CONCURRENT: usize = 1;

fn main() {
    let client = Client::new();

    let uri = "http://httpbin.org/ip".parse().unwrap();
    let uris = iter::repeat(uri).take(50);

    let work = stream::iter_ok(uris)
        .map(move |uri| client.get(uri))
        .buffer_unordered(N_CONCURRENT)
        .and_then(|res| {
            println!("Response: {}", res.status());
            res.into_body()
                .concat2()
                .map_err(|e| panic!("Error collecting body: {}", e))
        })
        .for_each(|body| {
            io::stdout()
                .write_all(&body)
                .map_err(|e| panic!("Error writing: {}", e))
        })
        .map_err(|e| panic!("Error making request: {}", e));

    tokio::run(work);
}

N_CONCURRENT 设置为 1：

real    0m2.279s
user    0m0.193s
sys     0m0.065s

并设置为 10：

real    0m0.529s
user    0m0.186s
sys     0m0.075s

另见：

• How can I perform parallel asynchronous HTTP GET requests with reqwest?