How to Use std

Use std::sync primitives like Mutex and Arc to safely share mutable state between threads by wrapping data and acquiring locks before access.

use std::sync::{Arc, Mutex};
use std::thread;

let counter = Arc::new(Mutex::new(0));
let mut handles = vec![];

for _ in 0..10 {
    let counter = Arc::clone(&counter);
    let handle = thread::spawn(move || {
        let mut num = counter.lock().unwrap();
        *num += 1;
    });
    handles.push(handle);
}

for handle in handles {
    handle.join().unwrap();
}

println!("Result: {}", *counter.lock().unwrap());

Think of std::sync as a set of traffic rules for your program's data when multiple threads try to use it at once. Mutex acts like a single-key lock on a shared resource, ensuring only one thread can modify the data at a time to prevent crashes. Arc allows multiple threads to own a reference to that same locked data safely.