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[英]thread '<main>' has overflowed its stack when creating a large array
[英]Thread '<main>' has overflowed its stack when allocating a large array using Box
我正在实施combsort 。 我想在堆栈上创建固定大小的数组,但它显示stack overflow
。 当我将它更改为在堆上时(Rust by Example 说在堆中分配我们必须使用Box
),它仍然显示stack overflow
。
fn new_gap(gap: usize) -> usize {
let ngap = ((gap as f64) / 1.3) as usize;
if ngap == 9 || ngap == 10 {
return 11;
}
if ngap < 1 {
return 1;
}
return ngap;
}
fn comb_sort(a: &mut Box<[f64]>) {
// previously: [f64]
let xlen = a.len();
let mut gap = xlen;
let mut swapped: bool;
let mut temp: f64;
loop {
swapped = false;
gap = new_gap(gap);
for i in 0..(xlen - gap) {
if a[i] > a[i + gap] {
swapped = true;
temp = a[i];
a[i] = a[i + gap];
a[i + gap] = temp;
}
}
if !(gap > 1 || swapped) {
break;
}
}
}
const N: usize = 10000000;
fn main() {
let mut arr: Box<[f64]> = Box::new([0.0; N]); // previously: [f64; N] = [0.0; N];
for z in 0..(N) {
arr[z] = (N - z) as f64;
}
comb_sort(&mut arr);
for z in 1..(N) {
if arr[z] < arr[z - 1] {
print!("!")
}
}
}
输出:
thread '<main>' has overflowed its stack
Illegal instruction (core dumped)
或者
thread 'main' has overflowed its stack
fatal runtime error: stack overflow
我知道我的堆栈大小不够,在创建一个函数内部太大的非堆数组时与 C++ 相同,但此代码使用堆但仍显示堆栈溢出。 这段代码到底有什么问题?
据我所知,似乎该代码仍在尝试先在堆栈上分配数组,然后再将其移入框中。
如果我像这样切换到Vec<f64>
代替Box<[f64]>
:
fn new_gap(gap: usize) -> usize {
let ngap = ((gap as f64) / 1.3) as usize;
if ngap == 9 || ngap == 10 {
return 11;
}
if ngap < 1 {
return 1;
}
return ngap;
}
fn comb_sort(a: &mut [f64]) {
// previously: [f64]
let xlen = a.len();
let mut gap = xlen;
let mut swapped: bool;
let mut temp: f64;
loop {
swapped = false;
gap = new_gap(gap);
for i in 0..(xlen - gap) {
if a[i] > a[i + gap] {
swapped = true;
temp = a[i];
a[i] = a[i + gap];
a[i + gap] = temp;
}
}
if !(gap > 1 || swapped) {
break;
}
}
}
const N: usize = 10000000;
fn main() {
let mut arr: Vec<f64> = std::iter::repeat(0.0).take(N).collect();
//let mut arr: Box<[f64]> = Box::new([0.0; N]); // previously: [f64; N] = [0.0; N];
for z in 0..(N) {
arr[z] = (N - z) as f64;
}
comb_sort(arr.as_mut_slice());
for z in 1..(N) {
if arr[z] < arr[z - 1] {
print!("!")
}
}
}
将来, box
语法将稳定。 当它是时,它将支持这种大分配,因为不需要对Box::new
函数调用,因此数组永远不会被放置在堆栈上。 例如:
#![feature(box_syntax)]
fn main() {
let v = box [0i32; 5_000_000];
println!("{}", v[1_000_000])
}
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