我创建了一个带有按钮的fltk窗口，当单击按钮时，按钮会生成一个线程，其中包含10次迭代，每次迭代都会向通道发送一条消息，使用println!（）时一切正常，但如果我删除它，通道就会开始跳过一些消息。

[dependencies]
fltk = { version="1.2.23", features=["fltk-bundled"] }
fltk-evented = "0.1"

use fltk::{prelude::*, *};
use std::{cell::RefCell, rc::Rc, thread};

fn main() {
    //create channel
    let (mainSender, mainReceiver) = app::channel::<i32>();

    //create application, window, button
    let mainApp = app::App::default();
    let mut win = window::Window::default().with_size(500, 500);
    let mut btn = button::Button::new(20, 20, 100, 40, "START");

    win.end();
    win.show();

    let mainSenderClone = mainSender.clone();

    btn.handle(move |thisBtn, evt| match evt {
        //btn event handler
        enums::Event::Push => {
            //click event

            thread::spawn(move || {
                //create thread

                let mut cnt = 0; //10 iterations
                while (cnt < 10) {
                    mainSenderClone.send(cnt);
                    //println!("sent_from_thread: {}",cnt); - uncommenting this fixes the situation
                    cnt += 1;
                }
            });

            true //event handled
        }

        _ => false, //ignore other events
    });

    //start listening
    while mainApp.wait() {
        if let Some(msg) = mainReceiver.recv() {
            println!("RECEIVED: {}", msg);
        }
    }
}

输出（线程中没有println!（））：

RECEIVED: 1
RECEIVED: 3
RECEIVED: 5
RECEIVED: 7
RECEIVED: 9

使用println!（）：

sent_from_thread: 0
RECEIVED: 0
sent_from_thread: 1
RECEIVED: 1
sent_from_thread: 2
RECEIVED: 2
sent_from_thread: 3
RECEIVED: 3
sent_from_thread: 4
RECEIVED: 4
sent_from_thread: 5
RECEIVED: 5
sent_from_thread: 6
RECEIVED: 6
sent_from_thread: 7
RECEIVED: 7
sent_from_thread: 8
RECEIVED: 8
sent_from_thread: 9
RECEIVED: 9