Hybrid C++ Pybind11/Panel integration Destructor issues. about panel

[tstrutz]

I may have figured out what was causing this. It looks like Panel is holding onto Panel resources even after the Python interpreter exits. Maybe a leak of some kind?

Anyways, I found that running pn.state.kill_all_servers() as the last line in main.py eliminates all of the problems here. I also moved all of the variables to a def main function so that there are zero global variables other than the app object. The weird thing with this is I am stopping the server. It shouldn't be running, unless the state is still left behind?

Why doesn't panel automatically do this clean up operation when Python exits? It's probably a good idea.

def main(app):
    # Pybinding object.
    launcher = AppLauncher(app)
    launcher.run()

if __name__ == "__main__":
    print("Creating C++ application")

    app = cpp_app_test.Application()

    print("C++ application created.")

    main(app)

    print("Exiting interpreter. Destructors should be called after this point!")

    pn.state.kill_all_servers()

produces the output:

Creating C++ application
Constructed application.
C++ application created.
Launching server at http://0.0.0.0:5000
^CCaught signal 2, shutting down...
Delete main page
Exiting interpreter. Destructors should be called after this point!
Delete home page
Destroyed application

I've noticed that the full application which contains a Sidebar and a Controller still doesn't work though. I may just reduce the number of references to self_app to fix this.