How to detect if cherrypy is shutting down

Question

I've made a server based on cherrypy but I have a repetitive task which takes a long time (more than a minute) to run. This is all fine until I need to shut down the server, then I am waiting forever for the threads to finish.

I was wondering how you'd detect a cherrypy shutdown inside the client thread so that the thread could abort when the server is shutting down.

I'm after something like this:

class RootServer:
    @cherrypy.expose

    def index(self, **keywords):
        for i in range(0,1000):
            lengthyprocess(i)
            if server_is_shutting_down():
                return

Answer 1

You can inspect the state directly:

if cherrypy.engine.state != cherrypy.engine.states.STARTED:
    return

Or, you can register a listener on the 'stop' channel:

class RootServer:

    def __init__(self):
        cherrypy.engine.subscribe('start', self.start)
        cherrypy.engine.subscribe('stop', self.stop)

    def start(self):
        self.running = True

    def stop(self):
        self.running = False

    @cherrypy.expose
    def index(self, **keywords):
        for i in range(0,1000):
            lengthyprocess(i)
            if not self.running:
                return

The latter is especially helpful if you also want to have the lengthyprocess start (or perform some preparation) when the server starts up, rather than upon a request.