rabbitmq(pika) throws an exception when use RPC

Question

RabbiMQ RPC throws an exception when i build publisher-consumer pattern. This is my code: sender.py

# coding:utf-8
import pika
import uuid


class MessageSender(object):

    def __init__(self):
        self.connention = pika.BlockingConnection(
            pika.ConnectionParameters(host='localhost'))
        self.channel = self.connention.channel()

        result = self.channel.queue_declare(exclusive=True)
        self.callback_queue = result.method.queue
        print 'MessageSender callback queue is ------', self.callback_queue
        self.channel.basic_consume(
            self.on_response, no_ack=True, queue=self.callback_queue)

    def on_response(self, ch, method, props, body):
        if self.corr_id == props.correlation_id:
            self.respose = body

    def send(self):
        self.respose = None
        self.corr_id = str(uuid.uuid4())
        self.channel.basic_publish(exchange='',
                                   routing_key='rpc_queue',
                                   properties=pika.BasicProperties(
                                       reply_to=self.callback_queue,
                                       correlation_id=self.corr_id,),
                                   body='MESSAGE')
        print '[x]Send sucessful'
        while self.respose is None:
            self.connention.process_data_events()
        print 'MessageSender get callback ------', self.respose


if __name__ == '__main__':
    sender = MessageSender()
    sender.send()

worker.py

# coding:utf-8
import pika
import time


class MessageWorker(object):

    def __init__(self):
        self.connection = pika.BlockingConnection(
            pika.ConnectionParameters(host='localhost'))
        self.channel = self.connection.channel()
        self.channel.queue_declare(queue='rpc_queue')

    def on_request(self, ch, method, props, body):
        print 'MessageWorker get message ------', body
        response = task(body)
        print 'MessageWorker callback on queue ------', props.reply_to
        ch.basic_publish(exchange='',
                         routing_key=props.reply_to,
                         properties=pika.BasicProperties(
                             correlation_id=props.correlation_id),
                         body=str(response))
        print 'MessageWorker send message to MessageSender'
        ch.basic_ask(delivery_tag=method.delivery_tag)

    def work(self):
        self.channel.basic_qos(prefetch_count=2)
        self.channel.basic_consume(self.on_request, queue='rpc_queue')
        print '[x]Waiting message...'
        self.channel.start_consuming()


def task(body):
    time.sleep(3)
    return body


if __name__ == '__main__':
    worker = MessageWorker()
    worker.work()

The sender works fine, but the worker.py always give a error:

[x]Waiting message...
MessageWorker get message ------ MESSAGE
MessageWorker callback on queue ------ amq.gen-6l5oJapbiKIqG3ZYTRwqpA
MessageWorker send message to MessageSender
Traceback (most recent call last):
  File "python/workers/new_worker.py", line 40, in <module>
    worker.work()
  File "python/workers/new_worker.py", line 30, in work
    self.channel.start_consuming()
  File "/usr/local/lib/python2.7/dist-packages/pika/adapters/blocking_connection.py", line 955, in start_consuming
    self.connection.process_data_events()
  File "/usr/local/lib/python2.7/dist-packages/pika/adapters/blocking_connection.py", line 243, in process_data_events
    raise exceptions.ConnectionClosed()
pika.exceptions.ConnectionClosed

This bothers me almost a week! Anyone can help? Thanks :)

Answer 1

Ok i knew what is going on. In worker.py, I misspell

ch.basic_ack(delivery_tag=method.delivery_tag)

to

ch.basic_ask(delivery_tag=method.delivery_tag)

My God!TT