import Pytorch to create Neural Network. Running Error

Question

I'm using C++/Qt to run my Qt application. Development Version: Python: 3.12 Qt: 6.6.3 C++: std 17 Visual Studio 2022

Inside my code, I use Python/C API to run python script like:

 PyObject* pModule = PyImport_ImportModule("DataModule");
 if (pModule == nullptr)
 {
 PyErr_Print();
 return QString();
 }
 PyObject* pFunc = PyObject_GetAttrString(pModule, "RunNeuralNetwork");
 PyObject* py_outputDir = QStringToPyObject(outputDir);
 PyObject* py_fileName = QStringToPyObject(fileName);
 PyObject* pArgs = PyTuple_New(4);
 PyTuple_SetItem(pArgs, 0, py_outputDir);
 PyTuple_SetItem(pArgs, 1, py_fileName);
 PyObject* pReturn = PyObject_CallObject(pFunc, pArgs);
 QString qString = PyObjectToQString(pReturn);

In "DataModule.py" file, I import Pytorch and create a Neural NetWork function. the code like:

import torch
from torch import nn
from torch.func import jacrev
from torch.utils.data import Dataset
from torch.utils.data import DataLoader
from multiprocessing import Pool
...
class NeuralNetwork(nn.Module):
 def __init__(self,
 dim_x: int,
 dim_y: int,
 num_hidden_layer: int,
 num_node: int,
 acti_name: str,
 kwarg_acti: dict = None,
 use_bn: bool = False,
 normal=None) -> None:
 super().__init__()
 activation_func = getattr(nn, acti_name)
 if kwarg_acti is None:
 kwarg_acti = dict()
 dim_list = [dim_x] + [num_node] * num_hidden_layer
 layer_list = []
 for i in range(num_hidden_layer):
 layer_list.append(nn.Linear(dim_list[i], dim_list[i + 1]))
 if use_bn:
 layer_list.append(nn.BatchNorm1d(dim_list[i + 1]))
 layer_list.append(activation_func(**kwarg_acti))
 layer_list.append(nn.Linear(dim_list[i + 1], dim_y))
 # layer_list.append(nn.BatchNorm1d(dim_y))
 self.layers = nn.Sequential(*layer_list)
 if normal is None:
 self.loc_x = torch.tensor(0.)
 self.loc_y = torch.tensor(0.)
 self.sca_x = torch.tensor(1.)
 self.sca_y = torch.tensor(1.)
 else:
 self.loc_x, self.loc_y, self.sca_x, self.sca_y = normal
 def forward(self, x):
 x = self.layers((x - self.loc_x) / self.sca_x)
 return x * self.sca_y + self.loc_y

When I run this code in C++ Python/C API, sometimes it runs well, and sometimes it crash.

It can not work neither in main thread or child thread.

The crash info in VS is:

0x00007FFE06A5EE30 (python311.dll) Exception in MyApp.exe 
0xC0000005: access violation reading 0xFFFFFFFFFFFFFFFF

I consider it is the problem of Multi Thread, then I use the below code In '.py' script

torch.set_num_threads(1)

It still not work.

Please Help!

use C++ through Python/C API runs '.py' script importing pytorch and no error.

• Ahmed AEK: 0xFFFFFFFFFFFFFFFF is -1 , do you check that all functions succeed ?
• Johnson Qing: yes, sometimes all functions succeed and run well. But when I try the same functions second or third time, it would crash irregularly, maybe first time or fifth or eighth time e.g.
• DavidW: You don't show enough code to reproduce this, and you're missing a lot of intermediate error checking (as AhmedAEK says). My guess would be that you're closing and restarting the Python interpreter multiple times. A lot of libraries don't like that so don't do it!
• Johnson Qing: Sorry I didn't describe it clearly. My PythonClass is a Singleton Class: static SingletonPython GetInstance(); ~SingletonPython(); So I init Python interpreter only one time, PyConfig_InitPythonConfig(&_config); and close when my app exit. In fact, in my code I check every pointer like pFunc, py_outputDir, pReturn, not showed in my above code. Sometimes it crashed in function 'PyImport_ImportModule' or 'PyObject_GetAttrString' getting 'PyObject' specially.