Rust使用reqwest初始化客户端类时程序崩溃问题求助

代码示例 #

use reqwest::Error;
use reqwest::header::{HeaderMap, HeaderValue, CONTENT_TYPE};
use reqwest::blocking::Client;
use reqwest::header;
use std::env;

struct GateClient {
    host: &'static str,
    prefix: &'static str,
    url: &'static str,
    key: String,
    secret: String,
    client: Client,
}

impl GateClient {
    fn new(key: &str, secret: &str) -> Self {
        let mut headers = header::HeaderMap::new();
        headers.insert(CONTENT_TYPE, HeaderValue::from_static("Accept=application/json"));
        headers.insert(CONTENT_TYPE, HeaderValue::from_static("Content-Type=application/json"));
    
        let client = Client::builder().default_headers(headers).build().unwrap();
        
        GateClient {
            host: "https://api.gateio.ws",
            prefix: "/api/v4",
            url: "/spot/currency_pairs/",
            key: key.to_string(),
            secret: secret.to_string(),
            client,
        }
    }

    fn get(&self, arg: &str) -> Result<String, reqwest::Error> {
        let url = format!("{}{}{}{}", self.host, self.prefix, self.url, arg);
        println!("{}", url);
        let response = self.client.get(&url).send()?;
        response.text()
    }
}

#[tokio::main]
async fn main() -> Result<(), Error> {
    env::set_var("RUST_BACKTRACE", "Full");

    let client = GateClient::new("a", "b");
    let response = client.get("ETH_USDT").unwrap();
    println!("{}", response);

    Ok(())
}

报错信息 #

thread 'main' panicked at
/home/nicolas/.cargo/registry/src/index.crates.io-6f17d22bba15001f/tokio-1.36.0/src/runtime/blocking/shutdown.rs:51:21: Cannot drop a runtime in a context where blocking is not allowed. This
happens when a runtime is dropped from within an asynchronous context.
stack backtrace: 0: rust_begin_unwind

错误原因 #

核心问题是混用了reqwest的阻塞客户端和Tokio异步运行时：

• 代码中使用reqwest::blocking::Client（阻塞式HTTP客户端），它内部会创建独立的阻塞线程池处理请求。
• 但main函数标记了#[tokio::main]，运行在Tokio的异步上下文里。程序结束时，GateClient中的阻塞客户端被销毁，这个销毁操作在Tokio异步线程中执行，而阻塞客户端的内部资源（如私有线程池）无法在异步上下文安全销毁，从而触发panic。

另外还有两个次要问题：

1. 两次插入CONTENT_TYPE头，后一次会直接覆盖前一次，正确做法是分别设置Accept和Content-Type两个独立的请求头。
2. 在异步main中直接调用阻塞的get方法，会阻塞Tokio的工作线程，破坏异步运行时的性能。

修复方案 #

方案1：改用reqwest异步客户端（推荐） #

将阻塞客户端替换为reqwest的异步版本，完全适配Tokio异步环境：

use reqwest::Error;
use reqwest::header::{HeaderMap, HeaderValue, ACCEPT, CONTENT_TYPE};
use reqwest::Client; // 移除blocking模块引用
use std::env;

struct GateClient {
    host: &'static str,
    prefix: &'static str,
    url: &'static str,
    key: String,
    secret: String,
    client: Client,
}

impl GateClient {
    fn new(key: &str, secret: &str) -> Self {
        let mut headers = HeaderMap::new();
        headers.insert(ACCEPT, HeaderValue::from_static("application/json")); // 正确设置Accept头
        headers.insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
    
        let client = Client::builder().default_headers(headers).build().unwrap();
        
        GateClient {
            host: "https://api.gateio.ws",
            prefix: "/api/v4",
            url: "/spot/currency_pairs/",
            key: key.to_string(),
            secret: secret.to_string(),
            client,
        }
    }

    // 将get方法改为异步函数
    async fn get(&self, arg: &str) -> Result<String, reqwest::Error> {
        let url = format!("{}{}{}{}", self.host, self.prefix, self.url, arg);
        println!("{}", url);
        let response = self.client.get(&url).send().await?; // 添加await关键字
        response.text().await
    }
}

#[tokio::main]
async fn main() -> Result<(), Error> {
    env::set_var("RUST_BACKTRACE", "Full");

    let client = GateClient::new("a", "b");
    let response = client.get("ETH_USDT").await.unwrap(); // 添加await关键字
    println!("{}", response);

    Ok(())
}

方案2：在Tokio阻塞线程中运行阻塞代码 #

如果坚持使用阻塞客户端，需将阻塞调用放到Tokio的阻塞线程池中执行，避免阻塞异步工作线程，同时确保客户端销毁在安全上下文：

// 其他代码保持不变，仅修改main函数
#[tokio::main]
async fn main() -> Result<(), Error> {
    env::set_var("RUST_BACKTRACE", "Full");

    // 在Tokio阻塞线程池内创建客户端并执行请求
    let response = tokio::task::spawn_blocking(|| {
        let client = GateClient::new("a", "b");
        client.get("ETH_USDT")
    }).await??; // 处理spawn_blocking和get方法的两层Result
    
    println!("{}", response);

    Ok(())
}

内容的提问来源于stack exchange，提问作者Nicolas Rey