摘要：今天介紹一下如何在項目中使用搭建一個有兩個節點的任務隊列一個主節點一個子節點主節點發布任務，子節點收到任務并執行。

今天介紹一下如何在django項目中使用celery搭建一個有兩個節點的任務隊列(一個主節點一個子節點；主節點發布任務，子節點收到任務并執行。搭建3個或者以上的節點就類似了)，使用到了celery,rabbitmq。這里不會多帶帶介紹celery和rabbitmq中的知識了。

1.項目基礎環境：
兩個ubuntu18.04虛擬機、python3.6.5、django2.0.4、celery3.1.26post2

2.主節點django項目結構：

3.settings.py中關于celery的配置：

import djcelery
# 此處的Queue和Exchange都涉及到RabbitMQ中的概念，這里不做介紹
from kombu import Queue, Exchange
djcelery.setup_loader()
BROKER_URL = "amqp://test:test@192.168.43.6:5672/testhost"
CELERY_RESULT_BACKEND = "amqp://test:test@192.168.43.6:5672/testhost"

CELERY_TASK_RESULT_EXPIRES=3600
CELERY_TASK_SERIALIZER="json"
CELERY_RESULT_SERIALIZER="json"
# CELERY_ACCEPT_CONTENT = ["json", "pickle", "msgpack", "yaml"]

CELERY_DEFAULT_EXCHANGE = "train"
CELERY_DEFAULT_EXCHANGE_TYPE = "direct"

CELERY_IMPORTS = ("proj.celery1.tasks", )

CELERY_QUEUES = (
  Queue("train", routing_key="train"),
  Queue("predict", routing_key="predict"),
)

4.celery.py中的配置：

# coding:utf8
from __future__ import absolute_import

import os

from celery import Celery
from django.conf import settings

# set the default Django settings module for the "celery" program.

os.environ.setdefault("DJANGO_SETTINGS_MODULE", "proj.settings")

app = Celery("proj")

# Using a string here means the worker will not have to
# pickle the object when using Windows.
app.config_from_object("django.conf:settings")
# app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)
app.autodiscover_tasks(settings.INSTALLED_APPS)


@app.task(bind=True)
def debug_task(self):
    print("Request: {0!r}".format(self.request))

5.proj/init.py中的配置：

from __future__ import absolute_import
from .celery import app as celery_app

6.celery1/tasks.py：（主節點中的任務不會執行，只執行子節點中的任務）

from __future__ import absolute_import
from celery import task


@task
def do_train(x, y):
    return x + y

7.celery1/views.py：

from .tasks import do_train
class Test1View(APIView):
    def get(self, request):
        try:
            # 這里的queue和routing_key也涉及到RabiitMQ中的知識
            # 關鍵，在這里控制向哪個queue中發送任務，子節點通過這個執行對應queue中的任務
            ret = do_train.apply_async(args=[4, 2], queue="train", routing_key="train")
            # 獲取結果
            data = ret.get()
        except Exception as e:
            return Response(dict(msg=str(e), code=10001))
        return Response(dict(msg="OK", code=10000, data=data))

8.子節點目錄結構：

9.子節點中celery1/celery.py：

from __future__ import absolute_import
from celery import Celery
CELERY_IMPORTS = ("celery1.tasks", )
app = Celery("myapp",
             # 此處涉及到RabbitMQ的知識，RabbitMQ是對應主節點上的
             broker="amqp://test:test@192.168.43.6:5672/testhost",
             backend="amqp://test:test@192.168.43.6:5672/testhost",
             include=["celery1.tasks"])

app.config_from_object("celery1.config")

if __name__ == "__main__":
  app.start()

10.子節點中celery1/config.py：

from __future__ import absolute_import
from kombu import Queue,Exchange
from datetime import timedelta

CELERY_TASK_RESULT_EXPIRES=3600
CELERY_TASK_SERIALIZER="json"
CELERY_RESULT_SERIALIZER="json"
CELERY_ACCEPT_CONTENT = ["json","pickle","msgpack","yaml"]

CELERY_DEFAULT_EXCHANGE = "train"
# exchange type可以看RabbitMQ中的相關內容
CELERY_DEFAULT_EXCHANGE_TYPE = "direct"

CELERT_QUEUES =  (
  Queue("train",exchange="train",routing_key="train"),
)

11.子節點celery1/tasks.py：(這個是要真正執行的task，每個節點可以不同)

from __future__ import absolute_import
from celery1.celery import app


import time
from celery import task


@task
def do_train(x, y):
    """
    訓練
    :param data:
    :return:
    """
    time.sleep(3)
    return dict(data=str(x+y),msg="train")

12.啟動子節點中的celery:
celery1是項目，-Q train表示從train這個queue中接收任務

celery -A celery1 worker -l info -Q train

13.啟動主節點中的django項目:

python manage.py runserver

14.使用Postman請求對應的view

請求url：http://127.0.0.1:8000/api/v1/celery1/test/
返回的結果是:
{
    "msg": "OK",
    "code": 10000,
    "data": {
        "data": "6",
        "msg": "train"
    }
}

15.遇到的問題：
1）celery隊列報錯: AttributeError: ‘str’ object has no attribute ‘items’
解決：將redis庫從3.0回退到了2.10，pip install redis==2.10
解決方法參考鏈接：https://stackoverflow.com/que...

今天就說到這里，如有疑問，歡迎交流。