该问题通常是由于并行执行时共享变量的生命周期错误引起的。为了解决这个问题,我们需要使用一些 Rust 提供的并发编程工具,例如 Mutex 和 Arc。
以下是一个解决示例:
use std::sync::{Arc, Mutex};
use std::thread;
fn segment_sieve(segment: &mut [bool], start: u64, limit: u64) {
for i in (2..limit).filter(|x| x*x < limit) {
if segment[(i-start) as usize] {
for j in ((start+i-1)/i..limit/i).map(|x| i*x) {
segment[(j-start) as usize] = false;
}
}
}
}
fn parallel_segment_sieve(n: u64, num_threads: usize) -> Vec {
let limit = (n as f64).sqrt() as u64 + 1;
let mut primes = vec![2u64];
let segment_size = (n as f64 / (num_threads as f64 * 2.0)).sqrt() as u64;
let segments: Vec<_> = (0..num_threads)
.map(|i| {
let start = segment_size * i as u64 * 2 + 3;
let end = start + segment_size * 2 - 2;
let mut segment = vec![true; segment_size as usize];
segment_sieve(&mut segment[..], start, end);
Arc::new(Mutex::new(segment))
}).collect();
for i in (3..limit).filter(|x| x%2 == 1) {
if segments.iter().all(|segment| {
segment.lock().unwrap()[(i/2-1) as usize]
}) {
primes.push(i);
for segment in &segments {
let mut sg = segment.lock().unwrap();
let start = (*sg)[0] as u64;
let start = if start%2 == 0 {start+1} else {start};
segment_sieve(&mut sg[..], start, (*sg).len() as u64 +