我有一堂课，有一本字典

class OrderBook:
    orders = {'Restaurant1': None,
              'Restaurant2': None,
              'Restaurant3': None,
              'Restaurant4': None}

    @staticmethod
    def addOrder(restaurant_name, orders):
        OrderBook.orders[restaurant_name] = orders

我正在运行4个线程（每个餐厅一个线程）来调用方法OrderBook.addOrder。这是每个线程运行的函数：

def addOrders(restaurant_name):

    #creates orders
    ...

    OrderBook.addOrder(restaurant_name, orders)

这样安全吗，还是在致电之前必须使用锁addOrder？