Threading module and embedded python

[Barry Scott]

> On 15 Apr 2020, at 13:30, Eko palypse <ekopalypse at gmail.com> wrote:
> 
> Hi everyone,
> 
> the following happens on Windows7 x64 and Python37 x64
> 
> I have a plugin DLL for a C++ application in which Python37 is embedded.
> The plugin itself works, except when I want to use the threading module.
> 
> If I start a Python script in my plugin which uses the threading module
> I can verify via ProcessExplorer that the thread is started,
> but it doesn't do anything (??) and the c++ application doesn't really do anything anymore either.
> 
> Only when I stop the C++ Applikation, the thread becomes active for a short time.
> Verified with logging module over time print-outs.
> 
> Apparently I did not understand everything about threads and embedded python.
> 
> Any idea what I'm doing wrong?

This is what I typically do.

Make sure that you have installed the Python debug files.
Now you can use the visual C++ debugger to attach to the process and
look at what the threads are doing.

I always have the python source code on hand to read as well.

This should give you a clue.

What is the "stuck" thread doing? waiting for a lock?

Barry




> 
> 
> The whole thing is initialized by the DllMain routine.
> 
> 
> BOOL APIENTRY DllMain( HANDLE hModule,
>                       DWORD  reasonForCall,
>                       LPVOID /* lpReserved */ )
> {
>    switch ( reasonForCall )
>    {
>        case DLL_PROCESS_ATTACH:
>            if (!Py_IsInitialized())
>            {
>                PyImport_AppendInittab("Npp", &PyInit_Npp);
>                Py_InitializeEx(0);
>                PyEval_InitThreads();  //<- this shouldn't be needed as I understand that it is called by Py_InitializeEx anyway
>            }
>            PyImport_ImportModule("Npp");
>            break;
>        case DLL_PROCESS_DETACH:
>            Py_Finalize();
>            break;
> 
>        case DLL_THREAD_ATTACH:
>            break;
> 
>        case DLL_THREAD_DETACH:
>            break;
>    }
> 
>    return TRUE;
> }
> 
> and the code in the plugin which executes the python scripts is this
> 
> cdef void run_code():
>    try:
>        global_dict = globals()
>        if '__name__' not in global_dict or global_dict['__name__'] != '__main__':
>            global_dict.update({"__name__": "__main__",})
>        exec(compile(editor.getText(), '<string>', 'exec'), global_dict)
> 
>    except Exception:
>        MessageBoxW(nppData._nppHandle,
>                    traceback.format_exc(),
>                    'RUN CODE EXCEPTION',
>                    0)  
> 
> I don't know if this is important, but the DLL is generated by Cython.
> 
> Thank you for reading and stay healthy
> 
> Eren
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> https://mail.python.org/mailman/listinfo/python-list
>