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
```shell
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
  Set custom prefetch multiplier value for
  this worker instance.
  Pool Options:
  
• -c, --concurrency
  Number of child processes processing the
  queue. The default is the number of CPUs
  available on your system.
  
  

### 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'