尝试使用 Celery+RabbitMQ 设置优先级队列时出现“PreconditionFailed - 队列的不等价参数‘x-max-priority’”错误

Question

我的 RabbitMQ 设置有两个队列：

low

和

high

。我希望我的芹菜工作人员在消耗低优先级队列的任务之前先消耗高优先级队列的任务。尝试将消息推送到 RabbitMQ 时出现以下错误

>>> import tasks
>>> tasks.high.apply_async()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/vagrant/.local/lib/python3.6/site-packages/celery/app/task.py", line 570, in apply_async
    **options
  File "/home/vagrant/.local/lib/python3.6/site-packages/celery/app/base.py", line 756, in send_task
    amqp.send_task_message(P, name, message, **options)
  File "/home/vagrant/.local/lib/python3.6/site-packages/celery/app/amqp.py", line 552, in send_task_message
    **properties
  File "/home/vagrant/.local/lib/python3.6/site-packages/kombu/messaging.py", line 181, in publish
    exchange_name, declare,
  File "/home/vagrant/.local/lib/python3.6/site-packages/kombu/connection.py", line 510, in _ensured
    return fun(*args, **kwargs)
  File "/home/vagrant/.local/lib/python3.6/site-packages/kombu/messaging.py", line 194, in _publish
    [maybe_declare(entity) for entity in declare]
  File "/home/vagrant/.local/lib/python3.6/site-packages/kombu/messaging.py", line 194, in <listcomp>
    [maybe_declare(entity) for entity in declare]
  File "/home/vagrant/.local/lib/python3.6/site-packages/kombu/messaging.py", line 102, in maybe_declare
    return maybe_declare(entity, self.channel, retry, **retry_policy)
  File "/home/vagrant/.local/lib/python3.6/site-packages/kombu/common.py", line 121, in maybe_declare
    return _maybe_declare(entity, channel)
  File "/home/vagrant/.local/lib/python3.6/site-packages/kombu/common.py", line 145, in _maybe_declare
    entity.declare(channel=channel)
  File "/home/vagrant/.local/lib/python3.6/site-packages/kombu/entity.py", line 609, in declare
    self._create_queue(nowait=nowait, channel=channel)
  File "/home/vagrant/.local/lib/python3.6/site-packages/kombu/entity.py", line 618, in _create_queue
    self.queue_declare(nowait=nowait, passive=False, channel=channel)
  File "/home/vagrant/.local/lib/python3.6/site-packages/kombu/entity.py", line 653, in queue_declare
    nowait=nowait,
  File "/home/vagrant/.local/lib/python3.6/site-packages/amqp/channel.py", line 1154, in queue_declare
    spec.Queue.DeclareOk, returns_tuple=True,
  File "/home/vagrant/.local/lib/python3.6/site-packages/amqp/abstract_channel.py", line 80, in wait
    self.connection.drain_events(timeout=timeout)
  File "/home/vagrant/.local/lib/python3.6/site-packages/amqp/connection.py", line 500, in drain_events
    while not self.blocking_read(timeout):
  File "/home/vagrant/.local/lib/python3.6/site-packages/amqp/connection.py", line 506, in blocking_read
    return self.on_inbound_frame(frame)
  File "/home/vagrant/.local/lib/python3.6/site-packages/amqp/method_framing.py", line 55, in on_frame
    callback(channel, method_sig, buf, None)
  File "/home/vagrant/.local/lib/python3.6/site-packages/amqp/connection.py", line 510, in on_inbound_method
    method_sig, payload, content,
  File "/home/vagrant/.local/lib/python3.6/site-packages/amqp/abstract_channel.py", line 126, in dispatch_method
    listener(*args)
  File "/home/vagrant/.local/lib/python3.6/site-packages/amqp/channel.py", line 282, in _on_close
    reply_code, reply_text, (class_id, method_id), ChannelError,
amqp.exceptions.PreconditionFailed: Queue.declare: (406) PRECONDITION_FAILED - inequivalent arg 'x-max-priority' for queue 'high' in vhost '/': received none but current is the value '10' of type 'signedint'

这是我的芹菜配置

import ssl
broker_url="amqps://"
result_backend="amqp://"
include=["tasks"]
task_acks_late=True
task_default_rate_limit="150/m"
task_time_limit=300
worker_prefetch_multiplier=1
worker_max_tasks_per_child=2
timezone="UTC"
broker_use_ssl = {'keyfile': '/usr/local/share/private/my_key.key', 'certfile': '/usr/local/share/ca-certificates/my_cert.crt', 'ca_certs': '/usr/local/share/ca-certificates/rootca.crt', 'cert_reqs': ssl.CERT_REQUIRED, 'ssl_version': ssl.PROTOCOL_TLSv1_2}
from kombu import Exchange, Queue
task_default_priority=5
task_queue_max_priority = 10
task_queues = [Queue('high', Exchange('high'), routing_key='high', queue_arguments={'x-max-priority': 10}),]
task_routes = {'tasks.high': {'queue': 'high'}}

我有一个

tasks.py

脚本，定义了以下任务

from __future__ import absolute_import, unicode_literals
from celery_app import celery_app

@celery_app.task
def low(queue='low'):
    print("Low Priority")

@celery_app.task(queue='high')
def high():
    print("HIGH PRIORITY")

还有我的

celery_app.py

脚本：

from __future__ import absolute_import, unicode_literals
from celery import Celery
from celery_once import QueueOnce
import celeryconfig

celery_app = Celery("test")
if __name__ == '__main__':
    celery_app.start()

我正在用这个命令启动芹菜工人

celery -A celery_app worker -l info --config celeryconfig --concurrency=16 -n "%h:celery" -O fair -Q high,low

我正在使用：

• RabbitMQ：2017 年 7 月 3 日
• 芹菜：4.3.0
• Python：3.6.7
• 操作系统：Ubuntu 18.04.3 LTS 仿生

Answer 1

最近我遇到了同样的问题并发现了这个问题。我决定为将来找到它的其他人发布可能的解决方案。

当前错误消息意味着该队列已声明为优先级 10，但现在其签名包含优先级

none

。例如，这里有一个与

x-expires

类似的问题，并有很好的解释：

Celery 坚持要求每个客户端提前知道队列是如何创建的。

为了解决此类问题，您可以更改以下内容：

• 更改

  task_queue_max_priority

  （定义队列

  x-max-priority

  的默认值）或删除它。
• 使用

  low

  声明队列

  queue_arguments={'x-max-priority': 10}

  ，就像对队列

  high

  所做的那样。

对我来说，当所有队列声明与之前创建的队列匹配时，问题就解决了。