我尝试使用Rust的时雄和reqwest crates重新实现以下Python代码。

#!/usr/bin/env python3

import asyncio
import httpx
import time

async def async_req(url, client):
    headers = {
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36 Edg/111.0.1661.54",
        "Cookie": ""
    }
    response = await client.get(url, headers=headers, timeout=180)
    print(response.status_code)
    print(response.text)

async def main():
    urls = ["http://localhost:5000/hello", "http://localhost:5000/world"]
    start = time.time()
    async with httpx.AsyncClient() as client:
        tasks = [async_req(url, client) for url in urls]
        await asyncio.gather(*tasks)
    print(time.time()-start)

if __name__ == "__main__":
    asyncio.run(main())

在Rust中实现的代码如下：

async fn async_req(
    url: &str,
    client: reqwest::Client,
) -> Result<reqwest::Response, Box<dyn std::error::Error>> {
    let response = client
        .get(url)
        .timeout(std::time::Duration::from_secs(180))
        .send()
        .await?;

    Ok(response)
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let urls = vec![
        "http://localhost:5000/hello",
        "http://localhost:5000/world",
    ];

    let mut handles = vec![];

    let client = reqwest::Client::new();
    for url in urls {
        let handle = {
            let client = client.clone();
            async move { async_req(url, client).await }
        };
        handles.push(handle);
    }

    let mut responses = vec![];
    for handle in handles {
        responses.push(handle.await?);
    }

    for response in responses {
        println!("{}", response.text().await?);
    }

    Ok(())
}

但是看起来这个程序并没有像在Python中那样发出异步请求。
我还没有找到一个不产生错误的解决方案。Cargo.toml的配置如下，我使用的Rust编译器版本是1.72.1（d5 c2 e9 c34，2023-09-13）。

[package]
name = "reqwest_async_demo"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
reqwest = { version = "^0.11" }
tokio = { version = "^1", features = [ "full" ] }