一、应用背景
今天做一个需求,要将RabbitMQ中的任务取出并执行,为防止任务执行期间出错,设置NO_ACK=FALSE标志,这样、一旦任务没有应答的话,相应的任务就会被RabbitMQ自动Re-Queue,避免丢失任务。然而、由于任务执行时间较长,通常需要五、六分钟,甚至更长;我们都知道一旦一个任务被取出执行,该任务就从Ready状态更改成Unacked状态。如图所示:
当这个任务执行完之后,程序将向RabbitMQ发送ACK消息确认,RabbitMQ在收到ACK消息后,会将该任务移出队列;然而、问题出在任务尚未执行完毕【执行时间太久】,RabbitMQ再等了一段时间【大约两三分钟】后,一直没有收到ACK确认消息,就将该任务自动Re-Queue了【我是一个生产者,一个消费者模式】,也就是说、我们这里发生了死循环【任务永远也执行不完,因为会一直Re-Queue】。
二、延长RabbitMQ ACK应答时间
到这里,我们急需解决的问题就是,怎么能设置RabbitMQ延长等待ACK的时间,百度一下、两下,各种读网络文档,研究操作RabbitMQ工作的文档,查了一圈资料也没查出怎么延长RabbitMQ ACK时间【废柴啊】。至此、一直查不出来,就想问一下网友的你,你知道怎么延长RabbitMQ接受ACK应答时间么?
三、改变解决问题方式
在查不出如何延长ACK应答时间后,我将注意力转向如何检测当前任务操作超时的,后来在官网看到这么一段话:
链接官网位置:http://www.rabbitmq.com/heartbeats.html#heartbeats-timeout
后面、就简单测试下将heartbeat参数设置为0,以禁用心跳检测,这样基本解决了我的问题;虽然官方不建议这么做,但也是一种解决思路,如果大家有什么更好的解决办法,烦请在下面留言【先谢谢啦】。
至此、这个问题基本阐述清楚了,如果有遇到的小伙伴,也请参考下上面的操作。
测试代码:
# import json
# from concurrent.futures import ThreadPoolExecutor
from queue import Queue
# from threading import Thread
from pika import BasicProperties, BlockingConnection, URLParameters
from pika.exceptions import ConnectionClosed
# from automation.aiclient.aiclient import AsyncAIRequestManager
class RabbitMQManager:
def __init__(self, host = 'localhost', qname = 'queue'):
self.params = URLParameters(host)
self.qname = qname
self.prod_conn = None
self.prod_chan = None
self.cons_conn = None
self.cons_chan = None
self.ai_signton = None
def init_prod_conn(self):
# create send connection
self.prod_conn = BlockingConnection(self.params)
self.prod_chan = self.prod_conn.channel()
self.prod_chan.queue_declare(queue = self.qname, durable = True)
def init_cons_conn(self):
# create receive connection
self.cons_conn = BlockingConnection(self.params)
self.cons_chan = self.cons_conn.channel()
self.cons_chan.basic_qos(prefetch_count = 1)
self.cons_chan.basic_consume(self.callback, queue = self.qname)
def produceMessages(self, msg = None):
try:
if isinstance(msg, str):
self.prod_chan.basic_publish(exchange = '',
routing_key = self.qname,
body = msg,
properties = BasicProperties(
delivery_mode = 2, # make message persistent
))
elif isinstance(msg, Queue):
while 0 != msg.qsize():
item = msg.get()
self.prod_chan.basic_publish(exchange = '',
routing_key = self.qname,
body = item,
properties = BasicProperties(
delivery_mode = 2, # make message persistent
))
else:
pass
except Exception as e:
if isinstance(e, ConnectionClosed):
print('Reconnection established!')
self.init_prod_conn()
# last connection close, re-produce msg
self.produceMessages(msg)
else:
print('Produce msg exception Occur, please check following error message:')
print(e)
def consumeMessages(self):
try:
self.cons_chan.start_consuming()
except Exception as e:
print('Consume msg exception Occur, please check following error message:')
print(e)
if isinstance(e, ConnectionClosed):
print('Reconnection established!')
self.init_cons_conn()
self.consumeMessages()
def callback(self, ch, method, properties, body):
# handle message body
print('callback....')
print(body)
try:
print('Consuming....')
self.cons_conn.process_data_events()
# 模拟处理任务时间
import time
time.sleep(300)
# if None == self.ai_signton:
# self.ai_signton = AsyncAIRequestManager()
# self.ai_signton.run(eval(json.loads(json.dumps(body.decode('utf-8')), encoding = 'utf-8')))
ch.basic_ack(delivery_tag = method.delivery_tag)
# t = Thread(target = self.ai_signton.syncToDatabase())
# t.start()
except Exception as e:
if isinstance(e, ConnectionClosed):
raise ConnectionClosed('Connection has been closed, send to reconnection.')
else:
print('Current error msg:')
print(e)
def close_prod_conn(self):
if None != self.prod_conn:
self.prod_conn.close()
def close_cons_conn(self):
if None != self.cons_conn:
self.cons_conn.close()
def close(self):
self.close_prod_conn()
self.close_cons_conn()