From 13c19c183111e21b8f9053268d4399604beed2cc Mon Sep 17 00:00:00 2001 From: "Christoph J. Scherr" Date: Thu, 1 Feb 2024 13:43:56 +0100 Subject: [PATCH] rayon example for wasting cpu time :) --- members/tokryon/src/main.rs | 62 ++++++++++++++++--------------------- 1 file changed, 27 insertions(+), 35 deletions(-) diff --git a/members/tokryon/src/main.rs b/members/tokryon/src/main.rs index c88f1f2..b3c1aca 100644 --- a/members/tokryon/src/main.rs +++ b/members/tokryon/src/main.rs @@ -1,43 +1,35 @@ -use std::sync::atomic::{AtomicU32, Ordering}; +use std::io::{prelude::*, Sink}; use rayon::prelude::*; -use tokio::{ - self, - time::{interval, Interval}, -}; -static THE_NUMBER: AtomicU32 = AtomicU32::new(0); - -#[inline] -fn incr() { - // just add it - THE_NUMBER.store(THE_NUMBER.load(Ordering::Relaxed) + 1, Ordering::Relaxed) -} - -#[inline] -fn get() -> u32 { - THE_NUMBER.load(Ordering::Relaxed) -} -#[inline] -async fn more() { - rayon::spawn(|| incr()) -} +// if we make these larger, our computer can be used as a heateršŸ”„ +type Danum = u16; +const CAP: usize = 1 << 14; #[tokio::main] async fn main() { - // Lets say that we want to add numbers FAST - println!("The number: {THE_NUMBER:?}"); - incr(); - assert_eq!(get(), 1); - println!("The number: {THE_NUMBER:?}"); - println!("starting the threads"); - let mut interval = interval(tokio::time::Duration::from_millis(100)); - loop { - tokio::select! { - _ = interval.tick() => { - println!("The number: {THE_NUMBER:?}"); - } - _ = more() => () - }; + // Lets say that we want to add many numbers FAST + let mut range: Vec = Vec::with_capacity(CAP); + // Initialize the values, probably zero + unsafe { + range.set_len(range.capacity()); } + let now = std::time::Instant::now(); + range.par_iter_mut().for_each(|num| { + let mut sink = Sink::default(); + while *num < Danum::MAX { + *num += 1; // cannot use `+=` on type `&u8` + let _ = write!(sink, "{num}"); // just to disable the compiler from calculating it all + // beforehand + } + }); + let sum: u128 = { range.par_iter().map(|n| *n as u128).sum::() }; + let eq = sum == CAP as u128 * Danum::MAX as u128; + println!( + "log cap: {}\nit worked: {eq}\nsum: {sum}\nlog_2(sum): {}\ntook: {:?}\nused threads: {}", + CAP.ilog2(), + sum.ilog2(), + now.elapsed(), + rayon::current_num_threads() + ); }