调用FFI进程时线程代码崩溃

Question

我已经将一个函数转换为使用线程（按照this answer）。它的行为与测试中预期的一样（也就是说，它向非线程版本返回相同的值）。但是，使用ctypes从Python调用它会导致调用进程崩溃。你知道吗

一是工作职能：

#[no_mangle]
pub extern fn convert_vec(lon: Array, lat: Array) -> Array {
    // snip
    // orig is a Vec<(f32, f32)>
    // convert is a conversion function
    let result: Vec<(i32, i32)> = orig.iter()
        .map(|elem| convert(elem.0, elem.1))
        .collect();
    // convert back to vector of unsigned integer Tuples
    let nvec = result.iter()
        .map(|ints| Tuple { a: ints.0 as u32, b: ints.1 as u32 })
        .collect();
    Array::from_vec(nvec)
}

现在是线程版本，它通过了测试（使用cargo test），但从Python调用时崩溃：

#[no_mangle]
pub extern fn convert_vec_threaded(lon: Array, lat: Array) -> Array {
    // snip
    // orig is a Vec<(f32, f32)>
    // convert is a conversion function
    let mut guards: Vec<JoinHandle<Vec<(i32, i32)>>> = vec!();
    // split into slices
    for chunk in orig.chunks(orig.len() / NUMTHREADS as usize) {
        let chunk = chunk.to_owned();
        let g = thread::spawn(move || chunk
            .into_iter()
            .map(|elem| convert(elem.0, elem.1))
            .collect());
        guards.push(g);
    }
    let mut result: Vec<(i32, i32)> = Vec::with_capacity(orig.len());
    for g in guards {
        result.extend(g.join().unwrap().into_iter());
    }
    // convert back to vector of unsigned integer Tuples
    let nvec = result.iter()
        .map(|ints| Tuple { a: ints.0 as u32, b: ints.1 as u32 })
        .collect();
    Array::from_vec(nvec)
}

完整的可测试示例可用here

Answer 1

从错误消息来看，您似乎对某些输入使用了0的块大小。[T]::chunks(size)将断言size != 0。你知道吗

如果我们想要NUMTHREADS块，我们可以这样分割它：

// Divide into NUMTHREADS chunks
let mut size = orig.len() / NUMTHREADS;
if orig.len() % NUMTHREADS > 0 { size += 1; }
// If we want to avoid the case where orig.len() == 0, we need another adjustment:
size = std::cmp::max(1, size);