Celery - run different workers on one server

Question

I have 2 kind of tasks : Type1 - A few of high priority small tasks. Type2 - Lot of heavy tasks with lower priority.

Initially i had simple configuration with default routing, no routing keys were used. It was not sufficient - sometimes all workers were busy with Type2 Tasks, so Task1 were delayed. I've added routing keys:

CELERY_DEFAULT_QUEUE = "default"
CELERY_QUEUES = {
    "default": {
        "binding_key": "task.#",
    },
    "highs": {
        "binding_key": "starter.#",
    },
}
CELERY_DEFAULT_EXCHANGE = "tasks"
CELERY_DEFAULT_EXCHANGE_TYPE = "topic"
CELERY_DEFAULT_ROUTING_KEY = "task.default"

CELERY_ROUTES = {
        "search.starter.start": {
            "queue": "highs",
            "routing_key": "starter.starter",
        },
}

So now i have 2 queues - with high and low priority tasks.

Problem is - how to start 2 celeryd's with different concurrency settings?

Previously celery was used in daemon mode(according to this), so only start of /etc/init.d/celeryd start was required, but now i have to run 2 different celeryds with different queues and concurrency. How can i do it?

Answer 1

Based on the above answer, I formulated the following /etc/default/celeryd file (originally based on the configuration described in the docs here: http://ask.github.com/celery/cookbook/daemonizing.html) which works for running two celery workers on the same machine, each worker servicing a different queue (in this case the queue names are "default" and "important").

Basically this answer is just an extension of the previous answer in that it simply shows how to do the same thing, but for celery in daemon mode. Please note that we are using django-celery here:

CELERYD_NODES="w1 w2"

# Where to chdir at start.
CELERYD_CHDIR="/home/peedee/projects/myproject/myproject"

# Python interpreter from environment.
#ENV_PYTHON="$CELERYD_CHDIR/env/bin/python"
ENV_PYTHON="/home/peedee/projects/myproject/myproject-env/bin/python"

# How to call "manage.py celeryd_multi"
CELERYD_MULTI="$ENV_PYTHON $CELERYD_CHDIR/manage.py celeryd_multi"

# How to call "manage.py celeryctl"
CELERYCTL="$ENV_PYTHON $CELERYD_CHDIR/manage.py celeryctl"

# Extra arguments to celeryd
# Longest task: 10 hrs (as of writing this, the UpdateQuanitites task takes 5.5 hrs)
CELERYD_OPTS="-Q:w1 default -c:w1 2 -Q:w2 important -c:w2 2 --time-limit=36000 -E"

# Name of the celery config module.
CELERY_CONFIG_MODULE="celeryconfig"

# %n will be replaced with the nodename.
CELERYD_LOG_FILE="/var/log/celery/celeryd.log"
CELERYD_PID_FILE="/var/run/celery/%n.pid"

# Name of the projects settings module.
export DJANGO_SETTINGS_MODULE="settings"

# celerycam configuration
CELERYEV_CAM="djcelery.snapshot.Camera"
CELERYEV="$ENV_PYTHON $CELERYD_CHDIR/manage.py celerycam"
CELERYEV_LOG_FILE="/var/log/celery/celerycam.log"

# Where to chdir at start.
CELERYBEAT_CHDIR="/home/peedee/projects/cottonon/cottonon"

# Path to celerybeat
CELERYBEAT="$ENV_PYTHON $CELERYBEAT_CHDIR/manage.py celerybeat"

# Extra arguments to celerybeat.  This is a file that will get
# created for scheduled tasks.  It's generated automatically
# when Celerybeat starts.
CELERYBEAT_OPTS="--schedule=/var/run/celerybeat-schedule"

# Log level. Can be one of DEBUG, INFO, WARNING, ERROR or CRITICAL.
CELERYBEAT_LOG_LEVEL="INFO"

# Log file locations
CELERYBEAT_LOGFILE="/var/log/celerybeat.log"
CELERYBEAT_PIDFILE="/var/run/celerybeat.pid"