# 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](https://docs.celeryq.dev/en/stable/index.html)
[Flower Documentation](https://flower.readthedocs.io/en/latest/auth.html)
### install "celery"
``` pip install -U "celery[redis]" ```
### 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 <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 add
>>> add.hello()
```
If your celery app set rsult backend
```
>>> from tasks import add  
>>> result = add.hello()
```
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'
```