celery安装配置（Windows）

1. 安装RabbitMQ，会提示安装Erlang，按照提示即可。
2. 确认RabbitMQ是否安装成功。
   a. 启动RabbitMQ Service
   b. 启动RabbitMQ Command Prompt (sbin dir)，执行：rabbitmqctl status。报错如下：

   Status of node rabbit@DESKTOP-P6AC70L ...
   Error: unable to perform an operation on node 'rabbit@DESKTOP-P6AC70L'. Please see diagnostics information and suggestions below.
   
   Most common reasons for this are:
   
    * Target node is unreachable (e.g. due to hostname resolution, TCP connection or firewall issues)
    * CLI tool fails to authenticate with the server (e.g. due to CLI tool's Erlang cookie not matching that of the server)
    * Target node is not running
   
   In addition to the diagnostics info below:
   
    * See the CLI, clustering and networking guides on http://rabbitmq.com/documentation.html to learn more
    * Consult server logs on node rabbit@DESKTOP-P6AC70L
   
   DIAGNOSTICS
   ===========
   
   attempted to contact: ['rabbit@DESKTOP-P6AC70L']
   
   rabbit@DESKTOP-P6AC70L:
     * connected to epmd (port 4369) on DESKTOP-P6AC70L
     * epmd reports node 'rabbit' uses port 25672 for inter-node and CLI tool traffic
     * TCP connection succeeded but Erlang distribution failed
   
     * Authentication failed (rejected by the remote node), please check the Erlang cookie
   
   
   Current node details:
    * node name: 'rabbitmqcli60@DESKTOP-P6AC70L'
    * effective user's home directory: C:\Users\junwe
    * Erlang cookie hash: aXFZrVZ2A9gF0kkNeMhRXA==
   

   c. 搜索.erlang.cookie（应该有两个），用任意一个替换另外一个保证内容一致。
   d. 重装RabbitMQ Service - 运行RabbitMQ Service - (re)install
   e. 重复步骤a、b，可以看到RabbitMQ Service已经运行起来。
   f. 启动RabbitMQ Command Prompt (sbin dir)，执行：rabbitmq-plugins enable rabbitmq_management
   g. 打开浏览器，输入http://127.0.0.1:15672，成功跳转至RabbitMQ管理界面。（不运行步骤f，页面无法访问）
3. 安装celery。在python环境下执行：pip install celery
4. 创建tasks.py：

   from celery import Celery
   import time
   
   app = Celery('tasks', backend='amqp', broker='amqp://')
   
   @app.task
   def add(x, y):
     time.sleep(5)
     return x + y
   

5. 切到tasks.py目录下运行：celery -A tasks worker --loglevel=info
   提示错误：

     -------------- celery@iZev0nc46ircftZ v4.1.0 (latentcall)
     ---- **** -----
     --- * ***  * -- Windows-10-10.0.14393-SP0 2018-04-19 21:24:48
     -- * - **** ---
     - ** ---------- [config]
     - ** ---------- .> app:         tasks:0x213343e6630
     - ** ---------- .> transport:   amqp://guest:**@localhost:5672//
     - ** ---------- .> results:     disabled://
     - *** --- * --- .> concurrency: 2 (prefork)
     -- ******* ---- .> task events: OFF (enable -E to monitor tasks in this worker)
     --- ***** -----
      -------------- [queues]
                   .> celery           exchange=celery(direct) key=celery
     
     
     [tasks]
       . tasks.add
     
     [2018-04-19 21:24:48,634: ERROR/MainProcess] consumer: Cannot connect to amqp://guest:**@127.0.0.1:5672//: [WinError 10042] 在 getsockopt 或 setsockopt 调用中指定的一个未知的、无效的或不受支持的选项或层次。.
     Trying again in 2.00 seconds...
     
     [2018-04-19 21:24:49,322: INFO/SpawnPoolWorker-2] child process 2956 calling self.run()
     [2018-04-19 21:24:49,353: INFO/SpawnPoolWorker-1] child process 5768 calling self.run()
     [2018-04-19 21:24:50,697: ERROR/MainProcess] consumer: Cannot connect to amqp://guest:**@127.0.0.1:5672//: [WinError 10042] 在 getsockopt 或 setsockopt 调用中指定的一个未知的、无效的或不受支持的选项或层次。.
     Trying again in 4.00 seconds...
   

   Google后发现是有个bug，由于amqp的版本太低没有被修复：https://github.com/celery/py-amqp/pull/136。由于我是anaconda环境，运行conda update --all把所有的package都更新了一下。再运行celery -A tasks worker --loglevel=info就可以了。
6. 在调用端运行如下代码：

   >>> from tasks import add
   >>> res = add.delay(4,4)
   >>> res.ready()
   False
   >>> res.ready()
   True
   >>> res.result
   8
   >>>
   

   切到celery的环境下看一下，发现报错了：

       The AMQP result backend is scheduled for deprecation in     version 4.0 and removal in version v5.0.     Please use RPC backend or a persistent backend.
   
     alternative='Please use RPC backend or a persistent backend.')
   [2018-04-20 16:27:26,581: INFO/SpawnPoolWorker-1] child process 4104 calling self.run()
   [2018-04-20 16:27:26,596: WARNING/SpawnPoolWorker-1] c:\programdata\anaconda3\lib\site-packages\celery\backends\amqp.py:68: CPendingDeprecationWarning:
       The AMQP result backend is scheduled for deprecation in     version 4.0 and removal in version v5.0.     Please use RPC backend or a persistent backend.
   
     alternative='Please use RPC backend or a persistent backend.')
   [2018-04-20 16:27:26,800: INFO/MainProcess] mingle: all alone
   [2018-04-20 16:27:26,846: INFO/MainProcess] celery@iZ15r2bhksa4s0Z ready.
   [2018-04-20 16:28:23,878: INFO/MainProcess] Received task: tasks.add[0a988088-95da-44a1-8c04-7c4581ad6f25]
   [2018-04-20 16:28:23,956: ERROR/MainProcess] Task handler raised error: ValueError('not enough values to unpack (expected 3, got 0)',)
   Traceback (most recent call last):
     File "c:\programdata\anaconda3\lib\site-packages\billiard\pool.py", line 358, in workloop
       result = (True, prepare_result(fun(*args, **kwargs)))
     File "c:\programdata\anaconda3\lib\site-packages\celery\app\trace.py", line 525, in _fast_trace_task
       tasks, accept, hostname = _loc
   ValueError: not enough values to unpack (expected 3, got 0)
   

   Google了一下发现celery 4.0版本后就放弃了对Windows的支持：https://github.com/celery/celery/issues/4178。找到一个workaround：
   1. pip install eventlet
   2. celery -A tasks worker --pool=eventlet
7. 使用redis作为backend
   a. pip install redis
   b. 代码改为：app = Celery('tasks', broker='redis://127.0.0.1:6379/0', backend='redis://127.0.0.1:6379/0')
   c. 安装/启动redis server
   d. 重复步骤5、6
8. 在两台机器上进行测试
   a. 修改tasks.py中的ip至rabbitmq/redis所在机器的公网网址
   b. 拷贝tasks.py到另外一个机器
   c. 在另外一个机器上执行pip install celery和pip install redis
   d. 重复步骤6