_process_polling_result 队列控制问题

当 watch 执行完后，线程仍在后台执行，notify_queue.get() 时读取不到数据导致异常。

客户端代码：

class InstallConfig:
    def __init__(self):
        logger.info("connect to nacos: {}, nameserver: {}, group: {}, dataId: {}",
                    NACOS_SERVER,
                    NACOS_NAMESPACE,
                    NACOS_GROUP,
                    NACOS_DATA_ID)

        self.client = nacos.NacosClient(NACOS_SERVER, namespace=NACOS_NAMESPACE)

        # 添加以下设置未能解决 add_config_watcher 退出时的线程异常
        # Exception in thread Thread-6 (_process_polling_result)，
        # self.client.set_options(default_timeout=1)
        # self.client.set_options(pulling_timeout=1)
        # self.client.set_options(pulling_config_size=3)
        self.client.set_options(callback_thread_num=10)

        self.client.add_config_watcher(NACOS_DATA_ID, NACOS_GROUP, self.config_watcher)
        self.config = yaml.safe_load(self.client.get_config(NACOS_DATA_ID, NACOS_GROUP))

    def config_watcher(self, args):
        logger.info("run config watcher: {}", args)
        self.config = yaml.safe_load(args["raw_content"])


if __name__ == "__main__":
    config = InstallConfig()

    for i in range(10):
        print(config.get_minio_config().server)
        time.sleep(1)

watcher 队列异常，watcher 能接受消息，但在 for 之后报如下异常

Exception in thread Thread-14 (_process_polling_result):
Traceback (most recent call last):
  File "/root/anaconda3/envs/lib/python3.10/threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "/root/anaconda3/envs/lib/python3.10/threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "/root/anaconda3/envs/lib/python3.10/site-packages/nacos/client.py", line 817, in _process_polling_result
    cache_key, content, md5 = self.notify_queue.get()
  File "/root/anaconda3/envs/lib/python3.10/multiprocessing/queues.py", line 103, in get
    res = self._recv_bytes()
  File "/root/anaconda3/envs/lib/python3.10/multiprocessing/connection.py", line 216, in recv_bytes
    buf = self._recv_bytes(maxlength)
  File "/root/anaconda3/envs/lib/python3.10/multiprocessing/connection.py", line 414, in _recv_bytes
    buf = self._recv(4)
  File "/root/anaconda3/envs/lib/python3.10/multiprocessing/connection.py", line 383, in _recv
    raise EOFError
EOFError

Start in nacos/client.py at _process_polling_result and inspect how notify_queue.get() is handled when add_config_watcher is no longer active. Reproduce the EOFError with the provided InstallConfig example and trace the watcher thread lifecycle. Done means the watcher can stop after the loop without emitting the queue exception.