Mastering Rust - Second Edition

Shared mutability with Arc and Mutex

Having explored the basics of Mutex in single threaded contexts, we'll revisit the example from the previous section. The following code modifies a value using a Mutex wrapped in an Arc from the multiple threads:

// arc_mutex.rsuse std::sync::{Arc, Mutex};use std::thread;fn main() {    let vec = Arc::new(Mutex::new(vec![]));    let mut childs = vec![];    for i in 0..5 {        let mut v = vec.clone();        let t = thread::spawn(move || {            let mut v = v.lock().unwrap();             v.push(i);        });        childs.push(t);    }    for c in childs {        c.join().unwrap();    }    println!("{:?}", vec);}

In the preceding code, we created a Mutex value in m. We then spawn a thread. The output on your machine may vary.

Calling lock on a mutex will block other threads ...