挂在 Rust 中的通道接收器迭代器中？

以下代码挂在迭代器中：（游乐场）

#![allow(unused)]
fn main() {
    use std::sync::mpsc::channel;
    use std::thread;
    
    let (send, recv) = channel();
    let num_threads = 3;
    for i in 0..num_threads {
        let thread_send = send.clone();
        thread::spawn(move || {
            loop { // exit condition does not matter, breaking right after the 1st iteration
                &thread_send.send(i).unwrap(); // have to borrow in the loop
                break;
            }
            println!("thread {:?} finished", i);
        });
    }

    // drop `send` needed here (as it's cloned by all producers)?
    
    for x in recv { // hanging
        println!("Got: {}", x);
    }
    println!("finished iterating");
}

在输出中，我们可以清楚地看到退出的线程（因此线程本地克隆的发件人被删除）：

thread 0 finished
Got: 0
Got: 1
Got: 2
thread 1 finished
thread 2 finished

finished iterating 永远不会打印并且该过程在操场上中断（在本地永远挂起）。

原因是什么？

附注。需要在线程中循环（这是实际使用的代码的简化示例）以显示真实用例。