从 MPSC 通道成功接收后进程永远不会退出

Question

这是代码：

use std::thread;
use std::sync::mpsc;

fn main() {

    //spawn threads 
    let (tx, rx) = mpsc::channel();
    for mut i in 0 .. 10 {
        let txc = tx.clone();   //clone from the main sender
        thread::spawn( move || {            
            i += 20;
            println!("Sending: {}", i);
            txc.send(i).unwrap_or_else(|e| {
                eprintln!("{}", e);
            });
        });
    }

    for received in rx {
        println!("Received: {}", received);
    }

}

代码成功运行，但它挂起并且进程最终永远不会退出。

我认为这可能与关闭通道结束有关，我尝试顺便拜访一下tx.drop()，rx.drop()但编译器给出了错误。

我在这里做错了什么？

Answer 1

tx在您的主线程中，直到函数结束才被删除main，并且rx直到所有发件人都被删除后才会关闭。

drop(tx)要解决此问题，您可以在启动所有线程后手动将其删除：

use std::thread;
use std::sync::mpsc;

fn main() {

    //spawn threads 
    let (tx, rx) = mpsc::channel();
    for mut i in 0 .. 10 {
        let txc = tx.clone();   //clone from the main sender
        thread::spawn( move || {            
            i += 20;
            println!("Sending: {}", i);
            txc.send(i).unwrap_or_else(|e| {
                eprintln!("{}", e);
            });
        });
    }

    // drop tx manually, to ensure that only senders in spawned threads are still in use
    drop(tx);

    for received in rx {
        println!("Received: {}", received);
    }

}