stop_server_weak.py

import threading
import weakref

from some_where import MyServer

class MyWeakKeyDictionary(weakref.WeakKeyDictionary):

    def __init__(self, *args, **kwgs):
        super().__init__(*args, **kwgs)
        remove = self._remove
        def _remove(k, selfref=weakref.ref(self)):
            self = selfref()
            if self is not None:
                try:
                    self.data[k].stop()
                except Exception:
                    pass
            return remove(k)
        self._remove = _remove

servers_pool = MyWeakKeyDictionary()

def get_server():
    current_thread = threading.current_thread()
    server = servers_pool.get(current_thread)
    if not server:
        server = MyServer()
        server.start()
        servers_pool[current_thread] = server
    return server

def handler(event):
    server = get_server()