Redis-Celery

Redis-Celery (Distributed Architecture)

This includes

• Redis
• Flower

Usage (docker-compose)

• start the system
  docker-compose up add -d run in background
  
• down the system
  ctrl-c or
  docker-compose down
  

Celery

Celery Documentation
Flower Documentation

install "celery"

### Starting the worker

celery -A proj worker

* Options
Worker Options:
  * -n, --hostname HOSTNAME         Set custom hostname (e.g., 'w1@%%h').  
                                    Expands: %%h (hostname), %%n (name) and %%d, (domain).  
  * -D, --detach                    Start worker as a background process.  
  * -S, --statedb PATH              Path to the state database. The extension  
                                  '.db' may be appended to the filename.  
  * -l, --loglevel [DEBUG|INFO|WARNING|ERROR|CRITICAL|FATAL]  
                                    Logging level.  
  * -O, --optimization [default|fair]  
                                    Apply optimization profile.  
  * --prefetch-multiplier <prefetch multiplier>  
                                    Set custom prefetch multiplier value for  
                                    this worker instance.  
Pool Options:  
  * -c, --concurrency <concurrency>  
                                    Number of child processes processing the  
                                    queue.  The default is the number of CPUs  
                                    available on your system.  
    
'''celery worker --help''' can get more infomation.  

### woker in Windows
add ``` --pool=solo ``` option   

### Calling the task
```shell
>>> from tasks import hello
>>> hello.delay()

If your celery app set rsult backend

>>> from tasks import hello  
>>> result = hello.delay()

The ready() method returns whether the task has finished processing or not:

>>> result.ready()
>>> False

You can wait for the result to complete, but this is rarely used since it turns the asynchronous call into a synchronous one:

>>> result.get(timeout=1)
>>> 'hello world'