Python删除Azure Service Bus死信队列消息遇迭代错误求助

我写了一段Python异步代码，用于删除Azure Service Bus主题死信队列（DLQ）中早于指定时间的消息：

import asyncio
from azure.servicebus.aio import ServiceBusClient 
from azure.servicebus import ServiceBusSubQueue
from azure.servicebus.management import ServiceBusAdministrationClient
from datetime import datetime
import pytz
import os
from dateutil.relativedelta import relativedelta

NAMESPACE_CONNECTION_STR = os.environ.get('NAMESPACE_CONNECTION_STR')
servicebus_mgmt_client = ServiceBusAdministrationClient.from_connection_string(NAMESPACE_CONNECTION_STR)
TOPIC_NAME = os.environ.get('TOPIC_NAME')
SUBSCRIPTION_NAME = os.environ.get('SUBSCRIPTION_NAME')
DAYS=os.environ.get('DAYS')
TARGET_DATE = datetime.now(tz=pytz.UTC) + relativedelta(hours=-int(DAYS))  # "-2" month old datetime from now. 
TOPIC_INFO_BEFORE = servicebus_mgmt_client.get_subscription_runtime_properties(TOPIC_NAME,SUBSCRIPTION_NAME).dead_letter_message_count
DELETE_COUNTER = 0
TOTAL_PROCESSED = 0

if TOPIC_NAME is None or SUBSCRIPTION_NAME is None:
    raise ValueError('TOPIC_NAME and SUBSCRIPTION_NAME must be passed!')

print(f"All messages that have Enqueued Time less than {TARGET_DATE} will be deleted.")
print(f"Number of dead-letter messages before deletion: {TOPIC_INFO_BEFORE}")


async def dlq_receiver(servicebus_client, topic_name, subscription_name):
    async with servicebus_client:
        global TOTAL_PROCESSED
        global DELETE_COUNTER
        receiver = servicebus_client.get_subscription_receiver(topic_name=TOPIC_NAME, subscription_name=SUBSCRIPTION_NAME, sub_queue=ServiceBusSubQueue.DEAD_LETTER)

        print("EntityPath: " + receiver.entity_path)
        messages = []
        async with receiver:
            while (True):
                try:
                    received_msgs = await receiver.receive_messages(max_wait_time=5, max_message_count=10)
                except asyncio.TimeoutError:
                    print("Timed out while waiting for messages")
                    continue
                TOTAL_PROCESSED += len(received_msgs)
                if len(received_msgs) == 0 or TOTAL_PROCESSED >= TOPIC_INFO_BEFORE:
                    print(f"Finished")
                    return
                for msg in received_msgs:
                    if msg.enqueued_time_utc < TARGET_DATE:

                        messages.append(msg)
                    else:
                        print("Message is not processed due to  EnqueuedDatetime: " + str(msg.enqueued_time_utc) + " sequenceNo.: " + str(msg.sequence_number))

                for mes in messages:
                  print("Processed message EnqueuedDatetime: " + str(mes.enqueued_time_utc) + " sequenceNo.: " + str(mes.sequence_number))
                  DELETE_COUNTER += 1
                  await receiver.complete_message(mes)
                messages.clear()
async def dlq_multiple_client(connection_string, topic_name, subscription_name):
    # Can increase this count to run more receiver clients.
    concurrent_receivers = 5

    client = ServiceBusClient.from_connection_string(connection_string)

    receiver_clients = [dlq_receiver(client, topic_name, subscription_name) for _ in range(concurrent_receivers)]
    await asyncio.gather(*receiver_clients)


if __name__ == '__main__':
    asyncio.run(dlq_multiple_client(NAMESPACE_CONNECTION_STR, TOPIC_NAME, SUBSCRIPTION_NAME))
    print(f"Clean up is completed! Total count of deleted messages: {DELETE_COUNTER}")
    TOPIC_INFO_AFTER = servicebus_mgmt_client.get_subscription_runtime_properties(TOPIC_NAME,SUBSCRIPTION_NAME).dead_letter_message_count
    print(f"Messages left in Dead Letter Queue: {TOPIC_INFO_AFTER}")

代码有时能执行成功，但修改concurrent_receivers数量、max_wait_time或max_message_count参数时，会抛出如下错误：

Traceback (most recent call last):
File "C:\Users\Davyd_Derkach\PycharmProjects\pythonProject\main.py", line 66, in <module>
asyncio.run(dlq_multiple_client(NAMESPACE_CONNECTION_STR, TOPIC_NAME, SUBSCRIPTION_NAME))
File "C:\Users\Davyd_Derkach\AppData\Local\Programs\Python\Python39\lib\asyncio\runners.py", line 44, in run
return loop.run_until_complete(main)
File "C:\Users\Davyd_Derkach\AppData\Local\Programs\Python\Python39\lib\asyncio\base_events.py", line 647, in run_until_complete
return future.result()
File "C:\Users\Davyd_Derkach\PycharmProjects\pythonProject\main.py", line 62, in dlq_multiple_client
await asyncio.gather(*receiver_clients)
File "C:\Users\Davyd_Derkach\PycharmProjects\pythonProject\main.py", line 41, in dlq_receiver
return
File "C:\Users\Davyd_Derkach\PycharmProjects\pythonProject\venv\lib\site-packages\azure\servicebus\aio_servicebus_client_async.py", line 136, in __aexit__
await self.close()
File "C:\Users\Davyd_Derkach\PycharmProjects\pythonProject\venv\lib\site-packages\azure\servicebus\aio_servicebus_client_async.py", line 224, in close
for handler in self._handlers:
File "C:\Users\Davyd_Derkach\AppData\Local\Programs\Python\Python39\lib\_weakrefset.py", line 65, in __iter__
for itemref in self.data:
RuntimeError: Set changed size during iteration

我参考网上建议尝试复制集合进行迭代，修改后的代码片段如下，但问题仍未解决：

for mes in messages:
    print("Processed message EnqueuedDatetime: " + str(mes.enqueued_time_utc) + " sequenceNo.: " + str(mes.sequence_number))
    DELETE_COUNTER += 1
    await receiver.complete_message(mes)
    messages.clear()

内容的提问来源于Stack Exchange，提问作者Goopalo David