busy_behavior.rs

//! This sample demonstrates creating a thread pool with 4 tasks and spawning 40 tasks that spin
//! for 100ms. It's expected to take about a second to run (assuming the machine has >= 4 logical
//! cores)

#![expect(clippy::print_stdout, reason = "Allowed in examples.")]

use bevy_platform::time::Instant;
use bevy_tasks::TaskPoolBuilder;
use core::time::Duration;

fn main() {
    let pool = TaskPoolBuilder::new()
        .thread_name("Busy Behavior ThreadPool".to_string())
        .num_threads(4)
        .build();

    let t0 = Instant::now();
    pool.scope(|s| {
        for i in 0..40 {
            s.spawn(async move {
                let now = Instant::now();
                while Instant::now() - now < Duration::from_millis(100) {
                    // spin, simulating work being done
                }

                println!(
                    "Thread {:?} index {} finished",
                    std::thread::current().id(),
                    i
                );
            });
        }
    });

    let t1 = Instant::now();
    println!("all tasks finished in {} secs", (t1 - t0).as_secs_f32());
}