Rust 线程比另一个线程运行得更多答案

【问题标题】：Rust thread runs more than anotherRust 线程比另一个线程运行得更多
【发布时间】：2022-11-25 22:34:23
【问题描述】：

大家下午好，我正在学习rust，我想问一个问题，在下面的代码中，一个线程总是比另一个线程工作得更多，线程之间似乎没有正常的工作分配。

我用 C++ 编写了相同的代码，它也能正常工作，有人可以帮助我并告诉我 Rust 哪里出错了吗？

代码：

use std::fmt;
use std::sync::{Arc, Mutex};
use std::thread;
use tokio::time::Duration;
struct Client {
    id: i32,
}
impl fmt::Display for Client {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        writeln!(f, "Client id: {:?}", self.id)
    }
}
fn main() {
    // ======================
    let client: Client = Client { id: 0 };
    let counter = Arc::new(Mutex::new(client));
    let mut handles = vec![];

    // ======================
    // THREAD 1
    // ======================
    let safe_client_1 = Arc::clone(&counter);
    let thread_1 = thread::spawn(move || loop {
        let mut num = safe_client_1.lock().unwrap();
        num.id += 1;
        print!("thread 1: {}", num);
        thread::sleep(Duration::from_secs(1));
    });
    handles.push(thread_1);

    // ======================
    // THREAD 2
    // ======================
    let safe_client_2 = Arc::clone(&counter);
    let thread_2 = thread::spawn(move || loop {
        let mut num = safe_client_2.lock().unwrap();
        num.id -= 1;
        print!("thread 2: {}", num);
        thread::sleep(Duration::from_secs(1));
    });

    loop {}
}

输出：

thread 1: Client id: 1
thread 1: Client id: 2
thread 2: Client id: 1
thread 2: Client id: 0
thread 2: Client id: -1
thread 2: Client id: -2
thread 2: Client id: -3
thread 2: Client id: -4
thread 2: Client id: -5
thread 2: Client id: -6
thread 2: Client id: -7
thread 1: Client id: -6
thread 2: Client id: -7
thread 2: Client id: -8
thread 2: Client id: -9
thread 2: Client id: -10
thread 2: Client id: -11
thread 2: Client id: -12
thread 2: Client id: -13
thread 2: Client id: -14
thread 2: Client id: -15
thread 2: Client id: -16
thread 2: Client id: -17
thread 2: Client id: -18
thread 2: Client id: -19
thread 2: Client id: -20
thread 2: Client id: -21
thread 2: Client id: -22
thread 2: Client id: -23
thread 2: Client id: -24
thread 2: Client id: -25
thread 2: Client id: -26
thread 2: Client id: -27

解决方案代码：

use std::fmt;
use std::sync::{Arc, Mutex};
use std::thread;
use tokio::time::Duration;
struct Client {
    id: i32,
}
impl fmt::Display for Client {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        writeln!(f, "Client id: {:?}", self.id)
    }
}
fn main() {
    // ======================
    let client: Client = Client { id: 0 };
    let counter = Arc::new(Mutex::new(client));

    // ======================
    // THREAD 1
    // ======================
    let safe_client_1 = Arc::clone(&counter);
    let thread_1 = thread::spawn(move || loop {
        let mut num = safe_client_1.lock().unwrap();
        num.id += 1;
        print!("thread 1: {}", num);
        drop(num);
        thread::sleep(Duration::from_secs(1));
    });

    // ======================
    // THREAD 2
    // ======================
    let safe_client_2 = Arc::clone(&counter);
    let thread_2 = thread::spawn(move || loop {
        let mut num = safe_client_2.lock().unwrap();
        num.id -= 1;
        print!("thread 2: {}", num);
        drop(num);

        thread::sleep(Duration::from_secs(1));
    });

    loop {}
}

输出：

thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0
thread 1: Client id: 1
thread 2: Client id: 0
thread 2: Client id: -1
thread 1: Client id: 0

【问题讨论】：

标签： rust

【解决方案1】：

你拿着锁睡觉。改为这样做：

let thread_1 = thread::spawn(move || loop {
    let mut num = safe_client_1.lock().unwrap();
    num.id += 1;
    print!("thread 1: {}", num);
    drop(num);
    thread::sleep(Duration::from_secs(1));
});

【讨论】：

还有主线程忙循环（与工人冲突）似乎不太理想。
哇这么简单 kkkkk，非常感谢你解决了问题！
@Masklinn 我该怎么办？能给我举个例子？
@ClaudioSilva join() 在子线程上等待它们完成。这似乎是您通过将其中之一添加到 handles 的向量而开始做的事情。
或者只是在主线程中运行 thread_2 的代码。