Failing notify_one

use parking_lot::{Mutex, Condvar}; // 0.7.1
use std::{thread, sync::Arc, time::Duration};

fn main() {
    let locks = Arc::new((Mutex::new(()), Condvar::new()));

    for i in 0..4 {
        let locks = locks.clone();
        let t = thread::spawn(move || {
            let mut guard = locks.0.lock();
            println!("Thread {} waiting", i);
            locks.1.wait(&mut guard);
            
            // Comment out the following wait to make it work
            println!("Thread {} waiting for 1ms", i);
            locks.1.wait_for(&mut guard, Duration::from_millis(1));
    
            println!("Thread {} notifying next: {}", i, locks.1.notify_one());
        });
    }
    
    thread::sleep(Duration::from_millis(100));
    locks.1.notify_one();
    
    thread::sleep(Duration::from_millis(1000));
    println!("main exiting");
}