Parallel iter

Parallel Iterator

use std::{ops::Range, time::Instant};

use rayon::prelude::*;

fn sum_of_squares_par(input: Range<i32>) -> Vec<i32> {
    input.into_par_iter().map(|i| i - 1).collect::<Vec<_>>()
}

fn sum_of_squares(input: Range<i32>) -> Vec<i32> {
    input.into_iter().map(|i| i - 1).collect::<Vec<_>>()
}

fn main() {
    let input = 1..1_000_000_000;
    let start = Instant::now();
    sum_of_squares(input);
    println!("plain iterator: {:?}", Instant::now() - start);

    let input = 1..1_000_000_000;
    let start = Instant::now();
    sum_of_squares_par(input);
    println!("parallel iterator: {:?}", Instant::now() - start);
}

Compiling state_machine_pattern v0.1.0 (/home/wonchul/me/rust/state_machine_pattern)
    Finished dev [unoptimized + debuginfo] target(s) in 0.39s
     Running `target/debug/state_machine_pattern`
plain iterator: 29.321507442s
parallel iterator: 3.022041206s