WORK QUEUE --FAIR TASK DISPATCHER

通过消息队列来模拟了一个任务producer，在exchange以后，被均匀的分配到两个各队列当中，来进行作业的时间执行。可以根据实际的需要来进行任务调度或是负载均衡。

将任务分发给两个worker

以及通过参数prefetch来实现负载的均衡

#!C:\Python27\Scripts
import pika
import sys

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

channel.queue_declare(queue='task_queue', durable=True)

message = ' '.join(sys.argv[1:]) or "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,)
connection.close()

#!C:\Python27\Scripts
import pika
import time

connection = 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'

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

程序的执行顺序，首先执行work.py,在两个console分别执行

然后运行producer程序，new_task 程序

H:\mq>new_task.py  f1......

 [x] Sent 'f1......'

H:\mq>new_task.py  f1.......

 [x] Sent 'f1.......'

H:\mq>new_task.py  f1........

 [x] Sent 'f1........'

H:\mq>new_task.py  f1.........

 [x] Sent 'f1.........'

H:\mq>new_task.py  f1..........

 [x] Sent 'f1..........'

H:\mq>new_task.py  f1...........

 [x] Sent 'f1...........'

work_task py 

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

 [x] Received 'f1.......'

 [x] Done

 [x] Received 'f1.........'

 [x] Done

 [x] Received 'f1...........'

 [x] Done

work_task py 

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

[x] Received 'f1......'

[x] Done

[x] Received 'f1........'

[x] Done

[x] Received 'f1..........'

[x] Done

可以确认的是任务确实实在量给worker之间进行fair  dispatcher

此例程中需要注意的地方时： 

delivery_mode = 2, # make message persistent用来保证队列中消息的持久化prefetch参数告诉exchange，只有exchange在收到task queue的ackonowledge后才能发送新的消息channel.basic_qos(prefetch_count=1)