python singleton

singleton.py

class Singleton(type):
    _instances = {}

    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super().__call__(*args, **kwargs)
        return cls._instances[cls]

xxx.py

import torch

import logging
import threading

from singleton import Singleton

log = logging.getLogger(__name__)
lock = threading.RLock()


class XxxService(metaclass=Singleton):

    def __init__(self):
        pass

    def xxx(self):
        with lock:
            pass