rabbitmq03 ack消息确认

ack消息确认

ack的产生是因为，如果消息发送给一个worker了，如果再运行期间，worker挂掉了，那我们的消息也就跟着worker丢了，为了保证worker挂掉不会带着消息一起挂掉，产生了ack确认机制

模拟

• 发送一条很长的消息
• ./rabbitmqctl list_queues name messages_ready messages_unacknowledged查看消息是否到达队列
• 运行worker然后暂停
• ./rabbitmqctl list_queues name messages_ready messages_unacknowledged消息跟着worker一起丢失了

处理消息

• 在回调函数中调用ch.basic_ack(delivery_tag = method.delivery_tag)来完成消息的消费确认

import pika
import time

connection = pika.BlockingConnection(pika.ConnectionParameters(
        host='localhost'))
channel = connection.channel()

channel.queue_declare(queue='hello')

print ' [*] Waiting for messages. To exit press CTRL+C'

def callback(ch, method, properties, body):
    print " [x] Received %r" % (body,)
    time.sleep(body.decode().count('.'))
    print " [x] Done"
    ch.basic_ack(delivery_tag = method.delivery_tag)

channel.basic_consume(callback,
                      queue='hello')
channel.start_consuming()

校验结果

• 发送消息

[root@tencent1 sbin]# ./rabbitmqctl list_queues name messages_ready messages_unacknowledged 
Listing queues ...
hello   1   0
...done.

• 运行worker

[root@tencent1 sbin]# ./rabbitmqctl list_queues name messages_ready messages_unacknowledged 
Listing queues ...
hello   0   1
...done.

• 停止worker

[root@tencent1 sbin]# ./rabbitmqctl list_queues name messages_ready messages_unacknowledged 
Listing queues ...
hello   1   0
...done.