Behavior change in message count

[optapla...@gmail.com]

Hello!

I have a problem with queue message count.

I'm using the Spring Rabbit cots to get the number of messages in a RabbitMQ queue.

In version 3.6.2 of RabbitMQ, the message count result was messages ready + messages unacknowledged.

And in version 3.6.10, it seems that the messages count is only messages ready.

I didn't see anything related in the release notes.

Can you please help me understand what has changed?

Thanks in advance,

SR

[Michael Klishin]

Where do you observe this count?

If it's queue.declare-ok responses, nothing has changed there in years. HTTP API had

a major revamp in 3.6.7 so something could have changed there but no one has reported this to date.

It could also be a change in Spring. 

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MK

Staff Software Engineer, Pivotal/RabbitMQ

[optapla...@gmail.com]

Thank you for your quick response.

I observe this using the Spring Rabbit (org.springframework.amqp) version 1.7.2.RELEASE :

                <groupId>org.springframework.amqp</groupId>
                <artifactId>spring-rabbit</artifactId>

I'm using this code:

Properties properties = rabbitAdmin.getQueueProperties(queueName);

if (properties != null) {                  

   Integer nMessages = Integer.valueOf(properties.get(RabbitAdmin.QUEUE_MESSAGE_COUNT).toString());

   LOGGER.debug("Queue {} properties: nMessages={}", queueName, nMessages);

}

From what I've seen here https://github.com/spring-projects/spring-amqp/blob/v1.7.2.RELEASE/spring-rabbit/src/main/java/org/springframework/amqp/rabbit/core/RabbitAdmin.java this COTS is using the queue.declare-ok.

Did I miss something?

Le mardi 18 juillet 2017 16:21:11 UTC+2, Michael Klishin a écrit :

Where do you observe this count?

If it's queue.declare-ok responses, nothing has changed there in years. HTTP API had

a major revamp in 3.6.7 so something could have changed there but no one has reported this to date.

It could also be a change in Spring. 

On Tue, Jul 18, 2017 at 5:18 PM, <optapla...@gmail.com> wrote:

Hello!

I have a problem with queue message count.

I'm using the Spring Rabbit cots to get the number of messages in a RabbitMQ queue.

In version 3.6.2 of RabbitMQ, the message count result was messages ready + messages unacknowledged.

And in version 3.6.10, it seems that the messages count is only messages ready.

I didn't see anything related in the release notes.

Can you please help me understand what has changed?

Thanks in advance,

SR

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[Michael Klishin]

You can quite easily compare two different versions without using Spring AMQP:

 * Declare a queue

 * Publish 10 messages to it over the default exchange

 * Consume 3 with manual acknowledgement mode using basic.get

 * Make sure that the state of Read vs Unacknowledged is what one'd expect in the management UI and `rabbitmqctl list_queues`

 * Declare the queue with passive = true and see inspect the result

I don't recall a single change in that area in a long time and no similar reports. Without hard evidence I'm more inclined to think

that your recollection of how things worked in 3.6.2 is incorrect.

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[Gary Russell]

RabbitAdmin.getQueueProperties() is simply a wrapper around a passive queue declaration...

DeclareOk declareOk = channel.queueDeclarePassive(queueName);

Properties props = new Properties();

props.put(QUEUE_NAME, declareOk.getQueue());

props.put(QUEUE_MESSAGE_COUNT, declareOk.getMessageCount());

props.put(QUEUE_CONSUMER_COUNT, declareOk.getConsumerCount());

return props;

...nothing has changed there either, for years.

[optapla...@gmail.com]

Ok, so I did a simple test with my system:

I publish 5 messages to a queue with 3 active consumers.

rabbitmqctl list_queues indicates 5 messages in the queue whereas Spring Rabbit indicates 2

Is that expected?

I will run the same test tomorrow with Rabbit 3.6.2 and Spring Rabbit 1.4.0.M1 and let you know the result.

[Michael Klishin]

rabbitmqctl list_queues can display messages in Ready state, in Unacknowledged state and total.

Spring AMQP (and queue.declare-ok) only reports messages in Ready state. IIRC this is a big vague

in the spec but RabbitMQ has been doing that since 1.0.

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[Michael Klishin]

I wasn't sufficiently clear: the user can decide what columns rabbitmqctl list_queues displays.

Compare `rabbitmqctl list_queues name messages messages_ready messages_unacknowledged` to

`rabbitmqctl list_queues`, for example.

Perhaps this explains the discrepancy?

[optapla...@gmail.com]

After running some tests with an older version of RabbitMQ, I can confirm that the behavior hasen't changed between 3.6.2 and 3.6.10.

So, is there a way to get the number of messages ready + unacknowledged using RabbitMQ Java Client ?

[Michael Klishin]

There is using HTTP API [1] and Hop [2].

1. http://www.rabbitmq.com/management.html

2. https://github.com/rabbitmq/hop

[optapla...@gmail.com]

Ok thanks, I will take a look at it.