RabbitMQ (i)--work Queues

RabbitMQ (i)--work Queues

The main purpose of RABBITMQ using work queues is to avoid resource-intensive tasks, which are different from the way a timed task is handled, but instead encapsulate the task as a message to be added to the queue. While Message Queuing is shared among multiple workers, they are free to pop out data for processing.

Persistent message Durability

In order to guaranteethe loss of messages caused by the unexpected restart of ' RABBITMQ ', the data can be persisted by setting the durable of the message, but it is necessary for both the producer and the consumer to set the persistence to take effect.

It should be noted that 'rabbitmq ' does not allow changing the properties of the message queue that has been created, and if a non-persisted Hello message queue has been created before, an error message is returned.

To set the persistence properties for Message Queuing (second parameter):

Channel.queue_declare (queue='hello', durable=true)

When a message is sent, you need to specify ' Delivery_mode ' for message persistence:

Channel.basic_publish (exchange=", routing_key="task_queue", body=  Message, Properties# make message persistent))

Average Distribution Fair Dispatch

'RABBITMQ ' implements the message sharing function by setting the ' Prefetch_count ' of the ' Basic.qos ' method. It tellsthe producers of ' RABBITMQ ' not to assign too many tasks to a consumer, that is, not to assign new tasks before consumers can handle the tasks they have received.

Channel.basic_qos (Prefetch_count=1)

Where Prefetch_count is the number of tasks that can be processed, and if the upper limit is not reached RABBITMQ will continue to push the task to the consumer.

Instance producer

#!/usr/bin/env python#Coding=utf-8ImportPikaImporttimeconnection=Pika. Blockingconnection (Pika. Connectionparameters (Host='localhost')) Channel=Connection.channel () channel.queue_declare (Queue='Task_queue', durable=True) forIinchRange (100): Message= str (i) +'Hello world!'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 (1) Connection.close ()

Consumers

#!/usr/bin/env python#Coding=utf-8ImportPikaImporttimeconnection=Pika. Blockingconnection (Pika. Connectionparameters (Host='localhost')) Channel=Connection.channel () channel.queue_declare (Queue='Task_queue', durable=True)Print '[*] waiting for messages. To exit Press CTRL + C'defCallback (ch, method, properties, body):Print "[x] Received%r"%(body,) Time.sleep (2)    Print "[x] done"Ch.basic_ack (Delivery_tag=method.delivery_tag) Channel.basic_qos (Prefetch_count=1) Channel.basic_consume (callback, queue='Task_queue') channel.start_consuming ()

RabbitMQ (i)--work Queues