如何使用python替换`set`

我目前面临一个问题，我给一个线程一个集合的引用，我希望能够用模拟的数据库调用替换该集合.到目前为止，我已经完成了

import logging
import threading
import time
from typing import Callable

from loguru import logger


class MonitorProduct:

    def __init__(self, term: str, is_alive: Callable[[str], bool]) -> None:
        self.is_alive = is_alive
        self.term = term

    def do_request(self) -> None:
        time.sleep(.1)
        while True:
            logger.info(f'Checking {self.term}')
            if not self.is_alive(self.term):
                logger.info(f'Deleting term from monitoring: "{self.term}"')
                return

            time.sleep(5)


# mocked database
def database_terms() -> set[str]:
    return {
        'hello world',
        'python 3',
        'world',
        'wth',
    }


def database_terms_2() -> set[str]:
    return {
        'what am I doing wrong',
    }


def main() -> None:
    terms: set[str] = set()

    while True:
        db_terms = database_terms()
        diff = db_terms - terms
        terms.symmetric_difference_update(db_terms)

        for url in diff:
            logger.info(f'Starting URL: {url}')
            threading.Thread(
                target=MonitorProduct(url, terms.__contains__).do_request
            ).start()

        time.sleep(2)

        # ----------------------------------------------- #

        db_terms = database_terms_2() 
        diff = db_terms - terms
        terms.symmetric_difference_update(db_terms) # <--- terms should only now contain `what am I doing wrong`

        # Start the new URLS
        for url in diff:
            logger.info(f'Starting URL 2: {url}')
            threading.Thread(
                target=MonitorProduct(url, terms.__contains__).do_request
            ).start()

        time.sleep(10)


if __name__ == '__main__':
    main()

我现在遇到的问题是，当我们执行第一个db调用时，它应该 for each 术语启动线程:

{
  'hello world',
  'python 3',
  'world',
  'wth',
}

正如你们所见，我们还 for each 线程发送了terms.__contains__.

当我们第二次调用db时，该集合应该替换terms到

{
  'what am I doing wrong',
}

由于以下原因，最终应退出四个运行线程:

def do_request(self) -> None:
        time.sleep(.1)
        while True:
            logger.info(f'Checking {self.term}')
            if not self.is_alive(self.term):
                logger.info(f'Deleting term from monitoring: "{self.term}"')
                return

            time.sleep(5)

然而，问题是，我们不能以行动取代条款

术语=…因为我们正在创建一个新的集合，然后将该集合绑定到变量术语，而线程仍然有一个对旧集合的引用.

我的问题是，如何在不绑定新集合的情况下更新到最新集合来替换旧术语？