This document describes the current stable version of Celery (4.0). For development docs, go here.

Source code for celery.backends.redis

# -*- coding: utf-8 -*-
"""Redis result store backend."""
from __future__ import absolute_import, unicode_literals

from functools import partial

from kombu.utils.functional import retry_over_time
from kombu.utils.objects import cached_property
from kombu.utils.url import _parse_url

from celery import states
from celery._state import task_join_will_block
from celery.canvas import maybe_signature
from celery.exceptions import ChordError, ImproperlyConfigured
from celery.five import string_t
from celery.utils import deprecated
from celery.utils.functional import dictfilter
from celery.utils.log import get_logger
from celery.utils.time import humanize_seconds

from . import async
from . import base

    import redis
    from kombu.transport.redis import get_redis_error_classes
except ImportError:                 # pragma: no cover
    redis = None                    # noqa
    get_redis_error_classes = None  # noqa

__all__ = ['RedisBackend']

You need to install the redis library in order to use \
the Redis result store backend.

E_LOST = 'Connection to Redis lost: Retry (%s/%s) %s.'

logger = get_logger(__name__)

class ResultConsumer(async.BaseResultConsumer):

    _pubsub = None

    def __init__(self, *args, **kwargs):
        super(ResultConsumer, self).__init__(*args, **kwargs)
        self._get_key_for_task = self.backend.get_key_for_task
        self._decode_result = self.backend.decode_result
        self.subscribed_to = set()

    def start(self, initial_task_id, **kwargs):
        self._pubsub = self.backend.client.pubsub(

    def on_wait_for_pending(self, result, **kwargs):
        for meta in result._iter_meta():
            if meta is not None:
                self.on_state_change(meta, None)

    def stop(self):
        if self._pubsub is not None:

    def drain_events(self, timeout=None):
        m = self._pubsub.get_message(timeout=timeout)
        if m and m['type'] == 'message':
            self.on_state_change(self._decode_result(m['data']), m)

    def consume_from(self, task_id):
        if self._pubsub is None:
            return self.start(task_id)

    def _consume_from(self, task_id):
        key = self._get_key_for_task(task_id)
        if key not in self.subscribed_to:

    def cancel_for(self, task_id):
        if self._pubsub:
            key = self._get_key_for_task(task_id)

[docs]class RedisBackend(base.BaseKeyValueStoreBackend, async.AsyncBackendMixin): """Redis task result store.""" ResultConsumer = ResultConsumer #: :pypi:`redis` client module. redis = redis #: Maximum number of connections in the pool. max_connections = None supports_autoexpire = True supports_native_join = True def __init__(self, host=None, port=None, db=None, password=None, max_connections=None, url=None, connection_pool=None, **kwargs): super(RedisBackend, self).__init__(expires_type=int, **kwargs) _get = if self.redis is None: raise ImproperlyConfigured(E_REDIS_MISSING.strip()) if host and '://' in host: url, host = host, None self.max_connections = ( max_connections or _get('redis_max_connections') or self.max_connections) self._ConnectionPool = connection_pool socket_timeout = _get('redis_socket_timeout') socket_connect_timeout = _get('redis_socket_connect_timeout') self.connparams = { 'host': _get('redis_host') or 'localhost', 'port': _get('redis_port') or 6379, 'db': _get('redis_db') or 0, 'password': _get('redis_password'), 'max_connections': self.max_connections, 'socket_timeout': socket_timeout and float(socket_timeout), 'socket_connect_timeout': socket_connect_timeout and float(socket_connect_timeout), } if url: self.connparams = self._params_from_url(url, self.connparams) self.url = url self.connection_errors, self.channel_errors = ( get_redis_error_classes() if get_redis_error_classes else ((), ())) self.result_consumer = self.ResultConsumer( self,, self.accept, self._pending_results, self._pending_messages, ) def _params_from_url(self, url, defaults): scheme, host, port, _, password, path, query = _parse_url(url) connparams = dict( defaults, **dictfilter({ 'host': host, 'port': port, 'password': password, 'db': query.pop('virtual_host', None)}) ) if scheme == 'socket': # use 'path' as path to the socket… in this case # the database number should be given in 'query' connparams.update({ 'connection_class': self.redis.UnixDomainSocketConnection, 'path': '/' + path, }) # host+port are invalid options when using this connection type. connparams.pop('host', None) connparams.pop('port', None) connparams.pop('socket_connect_timeout') else: connparams['db'] = path # db may be string and start with / like in kombu. db = connparams.get('db') or 0 db = db.strip('/') if isinstance(db, string_t) else db connparams['db'] = int(db) # Query parameters override other parameters connparams.update(query) return connparams
[docs] def on_task_call(self, producer, task_id): if not task_join_will_block(): self.result_consumer.consume_from(task_id)
[docs] def get(self, key): return self.client.get(key)
[docs] def mget(self, keys): return self.client.mget(keys)
[docs] def ensure(self, fun, args, **policy): retry_policy = dict(self.retry_policy, **policy) max_retries = retry_policy.get('max_retries') return retry_over_time( fun, self.connection_errors, args, {}, partial(self.on_connection_error, max_retries), **retry_policy)
[docs] def on_connection_error(self, max_retries, exc, intervals, retries): tts = next(intervals) logger.error( E_LOST.strip(), retries, max_retries or 'Inf', humanize_seconds(tts, 'in ')) return tts
[docs] def set(self, key, value, **retry_policy): return self.ensure(self._set, (key, value), **retry_policy)
def _set(self, key, value): with self.client.pipeline() as pipe: if self.expires: pipe.setex(key, self.expires, value) else: pipe.set(key, value) pipe.publish(key, value) pipe.execute()
[docs] def delete(self, key): self.client.delete(key)
[docs] def incr(self, key): return self.client.incr(key)
[docs] def expire(self, key, value): return self.client.expire(key, value)
[docs] def add_to_chord(self, group_id, result): self.client.incr(self.get_key_for_group(group_id, '.t'), 1)
def _unpack_chord_result(self, tup, decode, EXCEPTION_STATES=states.EXCEPTION_STATES, PROPAGATE_STATES=states.PROPAGATE_STATES): _, tid, state, retval = decode(tup) if state in EXCEPTION_STATES: retval = self.exception_to_python(retval) if state in PROPAGATE_STATES: raise ChordError('Dependency {0} raised {1!r}'.format(tid, retval)) return retval
[docs] def apply_chord(self, header, partial_args, group_id, body, result=None, options={}, **kwargs): # Overrides this to avoid calling # pylint: disable=method-hidden # Note that KeyValueStoreBackend.__init__ sets self.apply_chord # if the implements_incr attr is set. Redis backend doesn't set # this flag. options['task_id'] = group_id return header(*partial_args, **options or {})
[docs] def on_chord_part_return(self, request, state, result, propagate=None, **kwargs): app = tid, gid =, if not gid or not tid: return client = self.client jkey = self.get_key_for_group(gid, '.j') tkey = self.get_key_for_group(gid, '.t') result = self.encode_result(result, state) with client.pipeline() as pipe: _, readycount, totaldiff, _, _ = pipe \ .rpush(jkey, self.encode([1, tid, state, result])) \ .llen(jkey) \ .get(tkey) \ .expire(jkey, self.expires) \ .expire(tkey, self.expires) \ .execute() totaldiff = int(totaldiff or 0) try: callback = maybe_signature(request.chord, app=app) total = callback['chord_size'] + totaldiff if readycount == total: decode, unpack = self.decode, self._unpack_chord_result with client.pipeline() as pipe: resl, _, _ = pipe \ .lrange(jkey, 0, total) \ .delete(jkey) \ .delete(tkey) \ .execute() try: callback.delay([unpack(tup, decode) for tup in resl]) except Exception as exc: # pylint: disable=broad-except logger.exception( 'Chord callback for %r raised: %r',, exc) return self.chord_error_from_stack( callback, ChordError('Callback error: {0!r}'.format(exc)), ) except ChordError as exc: logger.exception('Chord %r raised: %r',, exc) return self.chord_error_from_stack(callback, exc) except Exception as exc: # pylint: disable=broad-except logger.exception('Chord %r raised: %r',, exc) return self.chord_error_from_stack( callback, ChordError('Join error: {0!r}'.format(exc)), )
def _create_client(self, **params): return self.redis.StrictRedis( connection_pool=self.ConnectionPool(**params), ) @property def ConnectionPool(self): if self._ConnectionPool is None: self._ConnectionPool = self.redis.ConnectionPool return self._ConnectionPool @cached_property
[docs] def client(self): return self._create_client(**self.connparams)
def __reduce__(self, args=(), kwargs={}): return super(RedisBackend, self).__reduce__( (self.url,), {'expires': self.expires}, ) @deprecated.Property(4.0, 5.0)
[docs] def host(self): return self.connparams['host']
@deprecated.Property(4.0, 5.0)
[docs] def port(self): return self.connparams['port']
@deprecated.Property(4.0, 5.0)
[docs] def db(self): return self.connparams['db']
@deprecated.Property(4.0, 5.0)
[docs] def password(self): return self.connparams['password']