多线程数据安全的单例模式

import threading
class Singleton:
    instance = None
    lock = threading.RLock()
    def __init__(self):pass
    
    def __new__(cls, *args, **kwargs):
        if cls.instance:
            return cls.instance
        with cls.lock:
            if cls.instance:
                return cls.instance
            cls.instance = object.__new__(cls)       
            return cls.instance
        
def task():
    single = Singleton()
    print(single)
for i in range(5):
    t = threading.Thread()
    t.start()