Django celery task execution - django

Question

I have 3 tasks in tasks.py file when demon is working only one task execute . Rest of two display in debug mode but not execute.
celery worker --concurrency=1
Is there any changes need ?
Edit :
#celery.decorators.periodic_task(run_every=datetime.timedelta(minutes=1))
def task1():
try:
sc = SampleCount.objects.get(pk=1)
except:
sc = SampleCount()
sc.num = sc.num + 1
sc.save()
return(sc)
same task2 for add data into SampleCount2(minute=2) and task3 for add data into SampleCount3(minute=3).
Now i run
python manage.py celeryd -E -B --loglevel=DEBUG
so it will display 3 task. but when I check status its display only 1 task1 active . No other two in scheduled.if i run
python manage.py celeryd -E -B --loglevel=DEBUG
command again then task3 is active and rest of two not working. How to run three task using one worker .
I have wait till 10 minute but only one task working(may be its task1, or task2 or task3 ).

Answer 1

It depends on what resources are available on server.
There is not such requirement, that number of tasks must be equal to number of workers. The only thing is needed to understand:
the more workers are running, the faster all tasks will be processed, but more server resources will be needed.
This command:
celery worker --concurrency=1
Will spawn two processes
1. Control process, that will manage workers
2. worker process, the one, that will actually do the job
And this command:
celery worker --concurrency=2
Will spawn three processes
1. Control process, that will manage workers
2. worker process #1, the one, that will actually do the job
2. worker process #2, the one, that will actually do the job
And so on.
One worker can process all of your tasks, but two worker will do it faster.