pyo3 calls yolov8 blocking

[Rainweic]

Bug Description

I wrote the prediction for YOLOv8 in Python and called it in Pyo3, but it got stuck during the prediction phase. It's normal to execute the Python script separately。

Steps to Reproduce

Step1 :

# yolov8.py
from ultralytics import YOLO


class YoloV8:

    def __init__(self):
        self.model = None

    def load_model(self, model_path):
        self.model = YOLO(model_path)

    def infer(self, img_path):
        res = self.model(img_path)
        return res


yolov8 = YoloV8()

Step2 :

use pyo3::prelude::*;

static PYTHON_FILE_PATH: &str = include_str!("yolov8.py");

pub struct DetModule {
    pub instance: Option<Py<PyAny>>
}

impl DetModule {
    pub fn new() -> Self {

        let mut det_module = Self { instance: None };

        Python::with_gil(|py| {
            let det: &PyModule = PyModule::from_code(py, PYTHON_FILE_PATH, "", "")
                .expect("Load det module error");
            let instance: Py<PyAny> = det.getattr("yolov8")
                .expect("Get obj yolov8 failed").into();
            det_module.instance = Some(instance);
        });

        det_module
    }

    pub fn load_model(&mut self, model_file: &str) {
        Python::with_gil(|py| {
            let args = (model_file,);
            self.instance.as_ref().unwrap()
                .call_method1(py, "load_model", args)
                .expect("Load model {model_file} failed");
        });
    }

    pub fn infer(&self, img_path: &str) -> Option<PyObject> {
        let mut infer_res = None;

        Python::with_gil(|py| {
            let args = (img_path,);
            let res = self.instance.as_ref().unwrap()
                .call_method1(py, "infer", args)
                .expect("Infer error, img path: {img_path}");
            // infer_res = Some(res);
        });

        infer_res
    }
}


fn main() {

    let mut yolo_module = model::DetModule::new();
    yolo_module.load_model("yolov8n.pt");
    let res = yolo_module.infer("/Users/new/Downloads/car.png");
    match res {
        None => {}
        Some(res) => println!("res: {:?}", res)
    };
}

Backtrace

No response

Your operating system and version

Macos

Your Python version (python --version)

Python 3.9.7

Your Rust version (rustc --version)

rustc 1.76.0-nightly (b10cfcd65 2023-11-29)

Your PyO3 version

0.20.0

How did you install python? Did you use a virtualenv?

Conda base env

Additional Info

No response

[davidhewitt]

Do you know what line this is blocking on? Can you attach a debugger and see what it is waiting for?

[Rainweic]

def infer(self, img_path):
res = self.model(img_path) <----- blocking...
return res

If I use python yolov8.py, it's normal to get the result of prediction😭

[davidhewitt]

Ok, so it looks like the deadlock is inside the yolo code. Can you attach a debugger and find what the deadlock is waiting for? This might prompt me for ideas on how this could be solved.

[Rainweic]

It doesn't feel like a deadlock, because when I run the py file alone it's predicted, and I add breakpoints with debugger and can't see exactly what line is stuck