How to use barrier for thread synchronization

Concurrency
2026-04-17T14:12:14+00:00
Use std::sync::Barrier to synchronize multiple threads by making them wait until all have reached a specific point before proceeding.

Use std::sync::Barrier to make multiple threads wait until they all reach a specific point before proceeding. Create a Barrier with the number of threads, clone it for each thread, and call .wait() to block until all threads arrive.

use std::sync::Barrier;
use std::thread;

fn main() {
    let num_threads = 4;
    let barrier = Arc::new(Barrier::new(num_threads));

    let mut handles = vec![];
    for _ in 0..num_threads {
        let b = barrier.clone();
        let handle = thread::spawn(move || {
            println!("Thread waiting at barrier");
            b.wait(); // Blocks until all threads arrive
            println!("Thread passed barrier");
        });
        handles.push(handle);
    }

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

Note: Import Arc from std::sync to share the barrier across threads.