Getting number of messages in a RabbitMQ queue

Question

We're using amqplib to publish/consume messages. I want to be able to read the number of messages on a queue (ideally both acknowledged and unacknowledged). This will allow me to show a nice status diagram to the admin users and detect if a certain component is not keeping up with the load.

I can't find any information in the amqplib docs about reading queue status.

Can someone point me in the right direction?

Afield

Check this answer #8193084 – Pickard

Thanks @mike, that's largely what I ended up doing when I had to reimplement some of this in C#. For the Python approach, I ended up hitting the rabbitmq-admin plugin and querying that instead. In any case, I appreciate the pointer. – Afield

Answer 1

Using pika:

import pika

pika_conn_params = pika.ConnectionParameters(
    host='localhost', port=5672,
    credentials=pika.credentials.PlainCredentials('guest', 'guest'),
)
connection = pika.BlockingConnection(pika_conn_params)
channel = connection.channel()
queue = channel.queue_declare(
    queue="your_queue", durable=True,
    exclusive=False, auto_delete=False
)

print(queue.method.message_count)

Using PyRabbit:

from pyrabbit.api import Client
cl = Client('localhost:55672', 'guest', 'guest')
cl.get_messages('example_vhost', 'example_queue')[0]['message_count']

Using HTTP

Syntax:

curl -i -u user:password http://localhost:15672/api/queues/vhost/queue

Example:

curl -i -u guest:guest http://localhost:15672/api/queues/%2f/celery           

Note: Default vhost is / which needs to be escaped as %2f

Using CLI:

$ sudo rabbitmqctl list_queues | grep 'my_queue'

Knowitall

The PyRabbit solution retrieves a message from the queue. I think you want to use cl.get_queue("example_vhost", "example_queue")['messages'] instead. – Viperish

How would you get the number of unack'd messages in a queue? – Sycamine

For pika: Just leaving this here because it bit me and cost me a couple of hours. It's important to understand that this is only the "true" number of messages if the consumers haven't prefetched too many messages. Refer to pika.readthedocs.io/en/stable/modules/… for the prefetch_count. – Enter

I believe queue declare with pika should be done this way: queue = channel.queue_declare(queue="your_queue", passive=True) This won't fail if say, the durable value of your declare statement mismatches that of the currently existing queue. – Eydie

Answer 2

following the answer of ChillarAnand you can get the value easily. the data is in the object.

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(
            host='localhost',
            port=5672,
            credentials=pika.credentials.PlainCredentials('guest', 'guest'),
        )
channel = connection.channel()
print(channel.queue_declare(queue="your_queue", durable=True,  exclusive=False,
                  auto_delete=False).method.message_count)

and you will get the exact message number

Downspout

Why did you just copy Chillar's answer over a year later? – Leigh

It was a different answer when i answered. look at the edit log... – Downspout

Answer 3

Using the Java API, you can do the following :

channel.queueDeclarePassive(queueName).getMessageCount()

I believe this is also available with amqplib (according to https://code.google.com/p/py-amqplib/source/browse/amqplib/client_0_8/channel.py#1356 it seems that queue_declare() returns a tuple with the message count)

If you need more precise metrics (especially nack message count), you need to use rabbitmqctl or rabbitmq_management. Rabbitmq_management is probably a good choice due to its HTTP API. More info : http://www.rabbitmq.com/management.html

Messroom

"Q: Using Python how to I..." - "A: Using Java you do..." -> -1 – Bypass

as of today, Python is not mentioned in the OP – Flavoring

amqplib is a python library and the question is tagged Python but I agree I could've been a lot clearer, so apologies for the confusion – Afield