在多线程中使用不带Arc的Mutex是否安全？

Question

lazy_static! {
    pub static ref A: Mutex<Vec<u8>> = Mutex::new(vec![]);
}

#[test]
fn test() {
    let mut handles = vec![];
    for _ in 0..100 {
        let handle = thread::spawn(|| for _ in 0..10000 { A.lock().unwrap().push(1); });
        handles.push(handle);
    }

    for handle in handles { handle.join().unwrap(); }
    println!("{}", A.lock().unwrap().len());
}

I got the output which was 1000000 , but I'm not sure this is a right way to collect the data in multithreading.

Should I change it to Arc<Mutex<_>> ?

Answer 1

This is safe, yes. Multithreading is exactly what mutexes are for. Arc doesn't give you anything you need here.

Note, of course, that your current code is horrendously inefficient. I hope your real use case does a lot more work between mutex locks than this.