Examples

Task Queue Example

Very simple task queue using pickle, with primitive support for priorities using different queues.

queues.py:

from kombu import Exchange, Queue

task_exchange = Exchange('tasks', type='direct')
task_queues = [Queue('hipri', task_exchange, routing_key='hipri'),
               Queue('midpri', task_exchange, routing_key='midpri'),
               Queue('lopri', task_exchange, routing_key='lopri')]

worker.py:

from __future__ import with_statement

from kombu.mixins import ConsumerMixin
from kombu.log import get_logger
from kombu.utils import kwdict, reprcall

from queues import task_queues

logger = get_logger(__name__)


class Worker(ConsumerMixin):

    def __init__(self, connection):
        self.connection = connection

    def get_consumers(self, Consumer, channel):
        return [Consumer(queues=task_queues,
                         callbacks=[self.process_task])]

    def process_task(self, body, message):
        fun = body['fun']
        args = body['args']
        kwargs = body['kwargs']
        logger.info('Got task: %s', reprcall(fun.__name__, args, kwargs))
        try:
            fun(*args, **kwdict(kwargs))
        except Exception, exc:
            logger.error('task raised exception: %r', exc)
        message.ack()

if __name__ == '__main__':
    from kombu import Connection
    from kombu.utils.debug import setup_logging
    setup_logging(loglevel='INFO')

    with Connection('amqp://guest:guest@localhost:5672//') as conn:
        try:
            Worker(conn).run()
        except KeyboardInterrupt:
            print('bye bye')

tasks.py:

def hello_task(who="world"):
    print("Hello %s" % (who, ))

client.py:

from __future__ import with_statement

from kombu.common import maybe_declare
from kombu.pools import producers

from queues import task_exchange

priority_to_routing_key = {'high': 'hipri',
                           'mid': 'midpri',
                           'low': 'lopri'}


def send_as_task(connection, fun, args=(), kwargs={}, priority='mid'):
    payload = {'fun': fun, 'args': args, 'kwargs': kwargs}
    routing_key = priority_to_routing_key[priority]

    with producers[connection].acquire(block=True) as producer:
        maybe_declare(task_exchange, producer.channel)
        producer.publish(payload,
                         serializer='pickle',
                         compression='bzip2',
                         exchange=task_exchange,
                         routing_key=routing_key)

if __name__ == '__main__':
    from kombu import Connection
    from tasks import hello_task

    connection = Connection('amqp://guest:guest@localhost:5672//')
    send_as_task(connection, fun=hello_task, args=('Kombu', ), kwargs={},
                 priority='high')

Table Of Contents

Previous topic

Consumers

Next topic

Simple Interface

This Page