Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
1.9k views
in Technique[技术] by (71.8m points)

rabbitmq - Consume multiple queues in python / pika

I am trying to create a consumer that would subscribe to multiple queues, and then process messages as they arrive.

The problem is that when there is some data already present in the first queue, it consumes the first queue and never goes to consume the second queue. However, when the first queue is empty, it does go to the next queue, and then consumes both queues simultaneously.

I had first implemented threading but want to steer clear of it, when pika library does it for me without much complexity. Below is my code:

import pika

mq_connection = pika.BlockingConnection(pika.ConnectionParameters('x.x.x.x'))
mq_channel = mq_connection.channel()
mq_channel.basic_qos(prefetch_count=1)


def callback(ch, method, properties, body):
    print body
    mq_channel.basic_ack(delivery_tag=method.delivery_tag)

mq_channel.basic_consume(callback, queue='queue1', consumer_tag="ctag1.0")
mq_channel.basic_consume(callback, queue='queue2', consumer_tag="ctag2.0")
mq_channel.start_consuming()
question from:https://stackoverflow.com/questions/24510310/consume-multiple-queues-in-python-pika

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

One possible solution is to use non blocking connection and consume messages.

import pika


def callback(channel, method, properties, body):
    print(body)
    channel.basic_ack(delivery_tag=method.delivery_tag)


def on_open(connection):
    connection.channel(on_channel_open)


def on_channel_open(channel):
    channel.basic_consume(callback, queue='queue1')
    channel.basic_consume(callback, queue='queue2')


parameters = pika.URLParameters('amqp://guest:guest@localhost:5672/%2F')
connection = pika.SelectConnection(parameters=parameters,
                                   on_open_callback=on_open)

try:
    connection.ioloop.start()
except KeyboardInterrupt:
    connection.close()

This will connect to multiple queues and will consume messages accordingly.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...