线程代码崩溃调用FFI进程

时间:2015-06-30 21:54:15

标签: python multithreading rust ffi

我已将一个函数转换为使用线程(根据this answer)。它在测试中表现得如预期的那样(也就是说,它会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。

首先,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,它通过测试(使用cargo test)但在从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here

1 个答案:

答案 0 :(得分:1)

从错误消息中可以看出,对于某些输入,您使用了0的块大小。 [T]::chunks(size)会声明size != 0

如果我们想要NUMTHREADS块,我们可以像这样拆分:

// 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);