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use tracing::{info, instrument};
use tracing_subscriber::prelude::*;
#[instrument]
fn fibonacci(n: usize) -> usize {
if n < 2 {
n
} else {
fibonacci(n - 1) + fibonacci(n - 2)
}
}
#[instrument]
fn fibonacci_parallel(n: usize) -> usize {
if n < 20 {
fibonacci(n - 1) + fibonacci(n - 2)
} else {
let (a, b) = rayon::join(|| fibonacci_parallel(n - 1), || fibonacci_parallel(n - 2));
if (a + b) > 1000 {
info!("Big number!");
}
a + b
}
}
fn main() {
rayon::ThreadPoolBuilder::new()
.thread_name(|idx| format!("Worker {idx}"))
.build_global()
.expect("Failed to build thread pool.");
let guard = if std::env::args().any(|arg| arg == "--no-trace") {
None
} else {
let (chrome_layer, guard) = tracing_chrome::ChromeLayerBuilder::new()
.include_args(true)
.build();
tracing_subscriber::registry().with(chrome_layer).init();
Some(guard)
};
let before = std::time::Instant::now();
println!("fibonacci_serial(24) -> {}", fibonacci(24));
println!("took {} s", before.elapsed().as_secs_f32());
if let Some(guard) = &guard {
guard.start_new(None);
}
let before = std::time::Instant::now();
println!("fibonacci_parallel(24) -> {}", fibonacci_parallel(24));
println!("took {} s", before.elapsed().as_secs_f32());
if let Some(guard) = &guard {
guard.start_new(None);
}
let before = std::time::Instant::now();
println!("fibonacci_parallel(20) -> {}", fibonacci_parallel(20));
println!("took {} s", before.elapsed().as_secs_f32());
}
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