前言: 针对高延时任务, 直接在一次网络请求中处理完毕会导致很不好的体验,
celery则可以不阻塞请求后台处理这些任务, 并且可以
使用django的models进行数据库操作.

环境

python models:

• celery-4.1.1
• redis-2.10.6
• django-1.11.7

其他:

• redis-3.2.9
• macos
• python3.6

创建django工程

django-admin startproject dc
cd dc
django-admin startapp main

此时项目结构如下

dc
|-- __init__.py
|-- main
|   |-- __init__.py
|   |-- admin.py
|   |-- apps.py
|   |-- migrations
|   |   `-- __init__.py
|   |-- models.py
|   |-- tests.py
|   `-- views.py
|-- settings.py
|-- urls.py
`-- wsgi.py

修改settings.py, 添加app

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'dc.main' //new added
]

修改dc/main/models.py, 创建新models

from django.db import models

# Create your models here.

class Person(models.Model):
    first_name = models.CharField(max_length=30)
    last_name = models.CharField(max_length=30)

创建根访问节点

dc/main/views.py

from django.shortcuts import render
from django.http import HttpResponse
# Create your views here.


def hello(request):
    return HttpResponse('hello world')

dc/urls.py

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^$', hello) //new added
]

依次执行以下语句, 初始化django各功能模块

python manage.py migrate
python manage.py makemigrations main
python manage.py sqlmigrate main 0001
python manage.py migrate

接下来python manage.py runserver, 访问http://127.0.0.1:8000 即可看到hello world.

启动redis

redis是作为celery中间件使用的, 用来存储消息队列.

redis解压后, 直接运行src/redis-server即可启动, 默认端口6379

配置celery

参考文档

创建dc/celery.py

#-*- coding:utf-8 -*-

import os
from celery import Celery

# set the default Django settings module for the 'celery' program.
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'dc.settings')

app = Celery('dc')

# Using a string here means the worker doesn't have to serialize
# the configuration object to child processes.
# - namespace='CELERY' means all celery-related configuration keys
#   should have a `CELERY_` prefix.
app.config_from_object('django.conf:settings', namespace='CELERY')

# Load task modules from all registered Django app configs.
app.autodiscover_tasks()

修改 dc/__init__.py

from .celery import app as celery_app

__all__ = ['celery_app']

修改 dc/settings.py, 设定 redis URL

CELERY_BROKER_URL = 'redis://127.0.0.1:6379/3'

创建dc/main/tasks.py

#-*- coding:utf-8 -*-

from celery import shared_task

@shared_task
def test():
    import time
    time.sleep(5)
    from dc.main.models import Person
    person = Person(first_name='smith', last_name='jhon')
    person.save()
    c = Person.objects.count()
    print(f'person count is {c}')

修改dc/main/views.py

def hello(request):
    from dc.main.tasks import test
    test.delay()
    return HttpResponse('hello world')

启动celery进程

celery -A dc worker -l info

接下来访问http://127.0.0.1:8000, 即可发现页面立刻返回, 并没有被time阻塞, 查看启动celery的窗口, 即可发现log以及打印的信息, 确定models可以正常使用.

おわり.