一、celery简介

1：celery是什么

　　Celery是一个python开发的异步分布式任务调度模块。

2：celery是使用场景

　　异步任务：将耗时操作任务提交给Celery去异步执行，比如发送短信/邮件、消息推送、音视频处理等等

　　定时任务：定时执行某件事情，比如每天数据统计

3：celery特点　

　　简单：一单熟悉了celery的工作流程后，配置和使用还是比较简单的。
　　高可用：当任务执行失败或执行过程中发生连接中断，celery 会自动尝试重新执行任务。
　　快速：一个单进程的celery每分钟可处理上百万个任务。
　　灵活：几乎celery的各个组件都可以被扩展及自定制。

4：工作原理

Celery的架构由三部分组成，消息中间件（message broker），任务执行单元（worker）和任务执行结果存储（task result store）组成。

消息中间件：Celery本身不提供消息服务，但是可以方便的和第三方提供的消息中间件集成。包括，RabbitMQ, Redis等等

任务执行单元：Worker是Celery提供的任务执行的单元，worker并发的运行在分布式的系统节点中。

任务结果存储：Task result store用来存储Worker执行的任务的结果，Celery支持以不同方式存储任务的结果，包括AMQP, redis等

二、Hello，Celery

1：版本介绍

　　在Django项目的环境下配合celery和redis使用异步调用

Django==3.0.4
celery==3.1.26.post2
django-celery==3.3.1
django-redis==4.7.0
redis==2.10.6　　

安装相应的软件包

　　pip install redis==2.10.6 -i https://pypi.tuna.tsinghua.edu.cn/simple
　　pip install django-redis==4.7.0 -i https://pypi.tuna.tsinghua.edu.cn/simple

2：场景介绍（异步）

　　比如，想泡壶茶喝。当时的情况是：开水没有；水壶要洗，茶壶，茶杯要洗；火已生了，茶叶也有了。怎么办？

　　办法甲：洗好水壶，灌上凉水，放在火上；在等待水开的时间里，洗茶壶、洗茶杯、拿茶叶；等水开了，泡茶喝。

　　办法乙：先做好一些准备工作，洗水壶，灌水烧水；坐待水开了，洗茶壶茶杯，拿茶叶；一切就绪，泡茶喝。

　　2.1 代码架构

　　2.2 首先要保证redis是可以正常使用的，参考斑马斑马-05-白云之上-Redis初识　　

from redis import StrictRedis
from django_redis import get_redis_connection

sr = StrictRedis("39.99.213.203", port=6379, db=1)


def set_redis():
    res = sr.set("name", "zhangsan")
    print(res)


def get_redis():
    res = sr.get("name")
    print(res)


if __name__ == '__main__':
    # 设置值
    set_redis()
    # 获取值
    get_redis()

redis测试

　　2.3 设置url和views还有茶方法，至此计划B可以运行

from django.contrib import admin
from django.urls import path
from course.views import planA,planB

urlpatterns = [
    path('admin/', admin.site.urls),
    path('planA/',planA,name='planA'),
    path('planB/', planB, name='planB')
]

url.py

from django.shortcuts import render
from django.http import JsonResponse
from course.tasks import CourseTask
from datetime import datetime
import time
from course import 茶

# Create your views here.
def planA(request):

    start_time = time.time()
    start_ = time.strftime("%H:%M:%S", time.localtime())
    print('A计划开始', start_time)
    pc = 茶.泡茶()
    pc.洗水壶()  # 1
    CourseTask.apply_async(('洗茶壶','洗茶杯', '拿茶叶'), queue='work_queue')
    pc.烧水()  # 15
    end_time = time.time()
    end_ = time.strftime("%H:%M:%S", time.localtime())
    spendtime = str((end_time - start_time))
    print('B计划结束', end_time)
    dict_content = {}
    dict_content.setdefault("beginTime", start_)
    dict_content.setdefault("endTime", end_)
    dict_content.setdefault("spendTime", spendtime)
    return JsonResponse(dict_content)
def planB(request):
    start_time = time.time()
    start_=time.strftime("%H:%M:%S", time.localtime())
    print('B计划开始', start_time)
    pc = 茶.泡茶()
    pc.洗水壶()    #1
    pc.烧水()      #15
    pc.洗茶壶()    #1
    pc.洗茶杯()    #1
    pc.拿茶叶()    #2
    end_time = time.time()
    end_=time.strftime("%H:%M:%S", time.localtime())
    spendtime = str((end_time - start_time))
    print('B计划结束', end_time)
    dict_content={}
    dict_content.setdefault("beginTime",start_)
    dict_content.setdefault("endTime",end_)
    dict_content.setdefault("spendTime",spendtime)
    return JsonResponse(dict_content)

view.py

import time


class 泡茶():
    def 洗水壶(self):
        time.sleep(1)

    def 烧水(self):
        time.sleep(15)

    def 洗茶壶(self):
        print("洗茶壶")
        time.sleep(1)

    def 洗茶杯(self):
        print("洗茶杯")
        time.sleep(1)

    def 拿茶叶(self):
        print("拿茶叶")
        time.sleep(2)

茶

　　2.4 创建任务和配置文件　　

# 创建任务
import time
from celery.task import Task
from course import 茶


class CourseTask(Task):
    name = 'course-task'
    def run(self, *args, **kwargs):
        pc = 茶.泡茶()
        actions = list(args)
        print(actions)
        for action in actions:
            if action == "洗茶壶":
                pc.洗茶壶()
                continue
            if action == "洗茶杯":
                pc.洗茶杯()
                continue
            if action == "拿茶叶":
                pc.拿茶叶()
                continue

tasks

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    # 'course.apps.App01Config',
    'course',
    'djcelery',
]

from .celeryconfig import *
#定义中间件：使用的对象
BROKER_BACKEND='redis'
#定义中间件：数据库地址
BROKER_URL='redis://39.99.213.203:6379/1'
#定义中间件：结果存储地址
CELERY_RESULT_BACKEND='redis://39.99.213.203:6379/2'

"""
Django settings for celeryDemo project.

Generated by 'django-admin startproject' using Django 3.0.4.

For more information on this file, see
https://docs.djangoproject.com/en/3.0/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/3.0/ref/settings/
"""

import os

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/3.0/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '^ry*-g$fr)j1vz-^w+zw2wz@7$^&h_3)f3_r_swyenqb+pfum_'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = []


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    # 'course.apps.App01Config',
    'course',
    'djcelery',
]
from .celeryconfig import *
#定义中间件：使用的对象
BROKER_BACKEND='redis'
#定义中间件：数据库地址
BROKER_URL='redis://39.99.213.203:6379/1'
#定义中间件：结果存储地址
CELERY_RESULT_BACKEND='redis://39.99.213.203:6379/2'
MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

ROOT_URLCONF = 'celeryDemo.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [os.path.join(BASE_DIR, 'templates')]
        ,
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'celeryDemo.wsgi.application'


# Database
# https://docs.djangoproject.com/en/3.0/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}


# Password validation
# https://docs.djangoproject.com/en/3.0/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/3.0/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/3.0/howto/static-files/

STATIC_URL = '/static/'

settings.py

import djcelery
from datetime import timedelta
djcelery.setup_loader()
CELERY_QUEUES = {
    'beat_tasks': {
        'exchange': 'beat_tasks',
        'exchange_type': 'direct',
        'binding_key': 'beat_tasks'
    },
    'work_queue': {
        'exchange': 'work_queue',
        'exchange_type': 'direct',
        'binding_key': 'work_queue'
    }
}
CELERY_DEFAULT_QUEUE = 'work_queue'


CELERY_IMPORTS=(
    'course.tasks'
)


#  有些情况下可以防止死锁
CELERYD_FORCE_EXECV = True

#  设置并发的worker数量
CELERYD_CONCURRENCY = 4

# 允许重试
CELERY_ACKS_LATE = True

#  每个worker最多执行100个任务被销毁，可以防止内存泄漏
CELERYD_MAX_TASKS_PER_CHILD = 100

#  单个任务的最大运行时间，超过就杀死
CELERYD_TASK_TIME_LEMIT = 12 * 30

#  定时任务
CELERYBEAT_SCHEDULE = {
    'task1': {
        'task': 'course-task',
        'schedule': timedelta(seconds=5),  # 每5秒执行一次
        'options': {
            'queue': 'beat_tasks'  # 当前定时任务是跑在beat_tasks队列上的
        }
    }
}

celeryconfig.py

3：测试　　

python manage.py runserver

python manage.py celery worker -l info （工人）启动worker节点来处理任务

python manage.py celery beat -l info （领导）启动定时任务，当到时间时，把任务放入broker中，broker检测到了，让worker去工作。

python manage.py celery flower 错误日志监控，启动时必须先启动worker

三、Hello，Celery 2

1：文件读写的demo

　　url中添加：path('add_test/', add_test, name='add_test'),

def add_test(request):
    from course.tasks import add
    from django.http import HttpResponse

    ctime = datetime.now()
    # 默认用utc时间
    utc_ctime = datetime.utcfromtimestamp(ctime.timestamp())
    from datetime import timedelta
    time_delay = timedelta(seconds=5)
    task_time = utc_ctime + time_delay
    result = add.apply_async(args=[4, 3], eta=task_time)
    print(result.id)#如果定了CELERY_RESULT_BACKEND 此时会把结果插入到redis数据库中
    return HttpResponse('ok')

原来的view页面定义一个add_test方法

@task
def add(a, b):
    with open('a.text', 'a', encoding='utf-8') as f:
        f.write('a')
    print(a + b)

原來的tasks中添加自定義函數

　　以下是完整内容　　

"""celeryDemo URL Configuration

The `urlpatterns` list routes URLs to views. For more information please see:
    https://docs.djangoproject.com/en/3.0/topics/http/urls/
Examples:
Function views
    1. Add an import:  from my_app import views
    2. Add a URL to urlpatterns:  path('', views.home, name='home')
Class-based views
    1. Add an import:  from other_app.views import Home
    2. Add a URL to urlpatterns:  path('', Home.as_view(), name='home')
Including another URLconf
    1. Import the include() function: from django.urls import include, path
    2. Add a URL to urlpatterns:  path('blog/', include('blog.urls'))
"""
from django.contrib import admin
from django.urls import path
from course.views import planA,planB,add_test

urlpatterns = [
    path('admin/', admin.site.urls),
    path('planA/',planA,name='planA'),
    path('planB/', planB, name='planB'),
    path('add_test/', add_test, name='add_test'),

]

urls.py

# 创建任务
import time
from celery import task
from celery.task import Task
from course import 茶


class CourseTask(Task):
    name = 'course-task'
    def run(self, *args, **kwargs):
        pc = 茶.泡茶()
        actions = list(args)
        print(actions)
        for action in actions:
            if action == "洗茶壶":
                pc.洗茶壶()
                continue
            if action == "洗茶杯":
                pc.洗茶杯()
                continue
            if action == "拿茶叶":
                pc.拿茶叶()
                continue

@task
def add(a, b):
    with open('a.text', 'a', encoding='utf-8') as f:
        f.write('a')
    print(a + b)

tasks.py

from django.shortcuts import render
from django.http import JsonResponse
from course.tasks import CourseTask
from datetime import datetime
import time
from course import 茶


# Create your views here.
def planA(request):
    start_time = time.time()
    start_ = time.strftime("%H:%M:%S", time.localtime())
    print('A计划开始', start_time)
    pc = 茶.泡茶()
    pc.洗水壶()  # 1
    CourseTask.apply_async(('洗茶壶', '洗茶杯', '拿茶叶'), queue='work_queue')
    pc.烧水()  # 15
    end_time = time.time()
    end_ = time.strftime("%H:%M:%S", time.localtime())
    spendtime = str((end_time - start_time))
    print('B计划结束', end_time)
    dict_content = {}
    dict_content.setdefault("beginTime", start_)
    dict_content.setdefault("endTime", end_)
    dict_content.setdefault("spendTime", spendtime)
    return JsonResponse(dict_content)


def planB(request):
    start_time = time.time()
    start_ = time.strftime("%H:%M:%S", time.localtime())
    print('B计划开始', start_time)
    pc = 茶.泡茶()
    pc.洗水壶()  # 1
    pc.烧水()  # 15
    pc.洗茶壶()  # 1
    pc.洗茶杯()  # 1
    pc.拿茶叶()  # 2
    end_time = time.time()
    end_ = time.strftime("%H:%M:%S", time.localtime())
    spendtime = str((end_time - start_time))
    print('B计划结束', end_time)
    dict_content = {}
    dict_content.setdefault("beginTime", start_)
    dict_content.setdefault("endTime", end_)
    dict_content.setdefault("spendTime", spendtime)
    return JsonResponse(dict_content)


def add_test(request):
    from course.tasks import add
    from django.http import HttpResponse

    ctime = datetime.now()
    # 默认用utc时间
    utc_ctime = datetime.utcfromtimestamp(ctime.timestamp())
    from datetime import timedelta
    time_delay = timedelta(seconds=5)
    task_time = utc_ctime + time_delay
    result = add.apply_async(args=[4, 3], eta=task_time)
    print(result.id)#如果定了CELERY_RESULT_BACKEND 此时会把结果插入到redis数据库中
    return HttpResponse('ok')

views.py

2：测试

五、Web监控管理服务-Flower

1：简介

Flower是Celery的一个实时监控和管理Web界面工具，目前仍在活跃的开发之中，但已经是一个很重要的可用工具了

2：使用

　　把大象装冰箱分三步，第一步：打开冰箱门，第二步：把大象放进去，第三步：关上冰箱门。

　　使用Flower也分三步，第一步：安装，第二步：启动，第三步：访问。

　　2.1 安装:使用pip安装Flower:

　　pip3 install flower -i https://pypi.tuna.tsinghua.edu.cn/simple/ --trusted-host pypi.tuna.tsinghua.edu.cn

　　2.2 运行 flower命令启动web-server：　　

　　python manage.py celery flower

　　2.3 web页面访问：

　　127.0.0.1:5555/dashboard

六、日志打印

1：日志设置

from celery.utils.log import get_task_logger
logger=get_task_logger(__name__)

logger.debug(actions)

# 创建任务
import time
from celery import task
from celery.task import Task
from course import 茶
from celery.utils.log import get_task_logger
logger=get_task_logger(__name__)

class CourseTask(Task):
    name = 'course-task'
    def run(self, *args, **kwargs):
        pc = 茶.泡茶()
        actions = list(args)
        logger.debug(actions)
        for action in actions:
            if action == "洗茶壶":
                pc.洗茶壶()
                continue
            if action == "洗茶杯":
                pc.洗茶杯()
                continue
            if action == "拿茶叶":
                pc.拿茶叶()
                continue

@task
def add(a, b):
    with open('a.text', 'a', encoding='utf-8') as f:
        f.write('a')
    print(a + b)