RabbitMQ - how to get queue size

Question

I want my python script to constantly run and check if queue size is zero before sending a task to queue. Below is a snippets:

#!/usr/bin/env python
import pika
import sys

while True:

    # establish connection with RabbitMQ server
    connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))
    channel = connection.channel()

    # create queue
    # durable=True make sure RabbitMQ never lose our queue
    rabbit_queue = channel.queue_declare(queue="task_queue", durable=True)

    queue_size = rabbit_queue.method.message_count
    if queue_size <= 0:
        message = get_message()
        channel.basic_publish(exchange='',
                              routing_key="task_queue",
                              body=message,
                              properties=pika.BasicProperties(
                                  delivery_mode=2,  # make message persistent
                              ))

        print " [x] Sent %r" % (message,)
        time.sleep(3)

    # close connection to flush network buffers AND ensure our message was actually delivered to RabbitMQ
    connection.close()

Is it a good practise to constantly re-establish the connection?

It is too broad. Most correct answer: It depends how often does this script run, what is your infrastructure, what is typical AMQP broker load. — pinepain, Feb 08 '15 at 16:06
this script runs as a background script. it nv stops (ie: while-loop). i created about 6 queues. each queue may have about 1500 task — chrizonline, Feb 08 '15 at 16:32
Just try as is. If you'll run into performance issue then you will definitely know what to do. — pinepain, Feb 08 '15 at 18:05
Hi, after more than 8 hours, the python script freezes. what should i do? — chrizonline, Feb 09 '15 at 13:12

jbg · Answer 1 · 2016-01-02T07:44:21.610

I don’t see any reason not to move the connection open/close outside the while loop:

#!/usr/bin/env python

import pika
import sys


# establish connection with RabbitMQ server
connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))

try:
    channel = connection.channel()

    # create queue
    # durable=True make sure RabbitMQ never lose our queue
    channel.queue_declare(queue="task_queue", durable=True)

    while True:
        rabbit_queue = channel.queue_declare(queue="task_queue", durable=True, passive=True)
        queue_size = rabbit_queue.method.message_count
        if queue_size <= 0:
            message = get_message()
            channel.basic_publish(exchange='',
                                  routing_key="task_queue",
                                  body=message,
                                  properties=pika.BasicProperties(
                                  delivery_mode=2,  # make message persistent
                                  ))

            print " [x] Sent %r" % (message,)
            time.sleep(3)
finally:
    connection.close()

RabbitMQ - how to get queue size

1 Answers1