Server Management

Celery With Supervisor

Celery is a task queue with a focus on real-time processing, while also supports task scheduling. Task queues are used as mechanisms to distribute work across multiple threads or machines. A task queues input is a unit of work called a task, dedicated worker processes and constantly monitor the queue for new work to perform. Celery communicates via messages using a  broker to mediate between workers and clients.To initiate a task client puts a message on the queue, then the broker delivers that message to a worker.

Note: You can get more about celery http://celery.readthedocs.org/en/latest/django/first-steps-with-django.html

To run celery in virtual environment need to type the following command in your virtual environment

export C_FORCE_ROOT="true"

In production, you will want to run the worker in the background as a daemon and sometimes there may be a chance of stopping of celery worker automatically then it should be restarted automatically. To do the tasks you need to use the tools provided like supervisord.

First, you need to install supervisor in your virtualenv and generate a configuration file.

$ pip install supervisor

    $ cd /path/to/your/project

    $ echo_supervisord_conf > supervisord.conf

Next, just add the following section in a configuration file:

[program:celeryd]

    command=python manage.py celery worker -l info

    stdout_logfile=/path/to/your/logs/celeryd.log

    stderr_logfile=/path/to/your/logs/celeryd.log

    autostart=true

    autorestart=true

    startsecs=10

    stopwaitsecs=600

It's a simplified version of the Celery supervisor configuration file, adapted to work with virtualenvs.

Just run supervisord in your project directory.

$ supervisord

create a file /etc/init.d/supervisord and configure your actual supervisord.conf in which celery is configured in DAEMON_ARGS as follows

DAEMON_ARGS="-c /path/to/supervisord.conf"

to run it

sudo chmod +x /etc/init.d/supervisord

and to automatically schedule it, do

sudo update-rc.d supervisord defaults

To Stop and Start the service

service supervisord stop
service supervisord start

Create a new file /etc/init/supervisor.conf. Its content should look like this:

description "supervisor"

    start on runlevel [2345]

    stop on runlevel [!2345]

    respawn

    chdir /path/to/supervisord

    exec supervisord

Note that we’re using the same supervisord configuration file we used before. No changes there…

We can now start and stop supervisord with the following commands

$ sudo stop supervisor

    $ sudo start supervisor
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