Thanks for making the issue clear.

My understanding is that,
all C++ destructors have to check Python interpreter before Py_DECREF,
like this.

``` cplusplus
  ~something() {
    // PyThreadState *_tstate = PyThreadState_GET();
    PyThreadState *_tstate = _PyThreadState_UncheckedGet();
    if (_tstate) {
      Py_DECREF(somelist);
    }
  }
```

Is this right?