ServiceBusReceiver.peek_messages when receive_mode=ServiceBusReceiveMode.RECEIVE_AND_DELETE, consumes 1 message.

[lubomirmatus]

• Package Name: azure-servicebus
• Package Version: 7.11.1 (in 7.8.2 was OK)
• Operating System: Windows 10 x64
• Python Version: 3.11.1

Describe the bug
ServiceBusReceiver with receive_mode=ServiceBusReceiveMode.RECEIVE_AND_DELETE method peek_messages consumes 1 message from topic/subscription. When receive_mode=ServiceBusReceiveMode.PEEK_LOCK then method peek_messages is working OK.
This behavior was spotted in azure-servicebus 7.1.11, for example older version 7.8.2 was OK.

To Reproduce
client = ServiceBusClient.from_connection_string(conn_str='my_connection', logging_enable=False)
receiver = client.get_subscription_receiver(topic_name='my_topic', subscription_name='my_subscription', receive_mode=ServiceBusReceiveMode.RECEIVE_AND_DELETE, keep_alive=0, prefetch_count=0)
messages = receiver.peek_messages(max_message_count=1000, timeout=10) # Peeks messages and consumes 1st message from topic.

Expected behavior
The method peek_messages should not modify topic and consume/delete messages.

[kashifkhan]

@lubomirmatus Im trying to reproduce this and I wanted to clarify a few things. Assuming my topic/subscription has 100 messages I should see the following behavior

• if I set receive_mode=ServiceBusReceiveMode.RECEIVE_AND_DELETE then only 1 message will come back
• If I set receive_mode=ServiceBusReceiveMode.PEEK_LOCK then up to 100 messages might come back ?

[github-actions]

Hi @lubomirmatus. Thank you for opening this issue and giving us the opportunity to assist. To help our team better understand your issue and the details of your scenario please provide a response to the question asked above or the information requested above. This will help us more accurately address your issue.

[lubomirmatus]

Hi @kashifkhan

When you have 100 messages in topic:

• if set receive_mode=ServiceBusReceiveMode.RECEIVE_AND_DELETE then 1st message is consumed (deleted from topic/subscription) and messages 2-100 are returned
• if set receive_mode=ServiceBusReceiveMode.PEEK_LOCK then all 100 messages are returned and topic/subscription is untached - all messages are still in topic.

[kashifkhan]

Thank you @lubomirmatus . I'm able to reproduce this on my end and will update this thread once we have a fix in place.

[kashifkhan]

@lubomirmatus just out of curiosity, we were wondering why set RECEIVE_AND_DELETE and then peek messages? PEEK_LOCK and complete messages ( with auto lock renewer) can work similarly

[lubomirmatus]

I have been performing debugging/tests of our system. In some points of code I wanted to see messages in the topic before they have been received and processed so I used peek to see them but not touch them. The recevier was created with RECEIVE_AND_DELETE mode, I expected that peek_messages does not consume messages, and then I found this strange behaviour.

[kashifkhan]

Thank you for the update @lubomirmatus . We are able to reproduce this and will update when the fix will go in

[swathipil]

Hi @lubomirmatus - We've found the bug and are currently working on the right fix. We'll keep you updated as continue to work on it. Thanks!

More info: Our default prefetch behavior should be "off". However, even when it's off, we're currently prefetching a message.

[swathipil]

Hi @lubomirmatus - We've merged the fix into the main branch of the repo. We will be releasing the fix this week. If you'd like to test out the change beforehand, you can build the wheel off of the main branch. Thanks!

[swathipil]

Hi @lubomirmatus - The fix has been released - https://pypi.org/project/azure-servicebus/7.11.3/

Thanks!

[lubomirmatus]

Ok, thank you.