Use scoped_interpreter in std::thread

[onelxj]

I have a struct Middleware in C++ and I want to hold scoped_interpreter py::object and event_loop_thread as fields.
In the method initialize I have some std::thread, that will invoke some python code there.

Since it is multithreaded, I want to acquire in the thread, but it just blocks and hangs, no error is thrown, the release before the thread start didn't help as well.

Any suggestions please?

No other code running.

struct Middleware{
  void initialize(){
    py::gil_scoped_release release; // didn't help ???
    event_loop_runner = std::thread([&]() {
      {
        {
          py::gil_scoped_acquire acquire; // ??? blocks for some reason
          py::object module = py::module::import("simple.python");
          event_loop_thread = module.attr("EventLoopThread")();
          event_loop_thread.attr("start")(); // non-blocking
        }
        std::unique_lock<std::mutex> lock(python_thread_lock_);
        cv.wait(lock, [&]() { return !is_running; }); // block until stop called.
      }
    });
  }

  pybind11::scoped_interpreter guard;
  py::object event_loop_thread;
   std::thread event_loop_runner;
};