This document describes the current stable version of Celery (5.2). For development docs, go here.
Source code for celery.worker.strategy
"""Task execution strategy (optimization)."""
import logging
from kombu.asynchronous.timer import to_timestamp
from kombu.utils.encoding import safe_repr
from celery import signals
from celery.app import trace as _app_trace
from celery.exceptions import InvalidTaskError
from celery.utils.imports import symbol_by_name
from celery.utils.log import get_logger
from celery.utils.saferepr import saferepr
from celery.utils.time import timezone
from .request import create_request_cls
from .state import task_reserved
__all__ = ('default',)
logger = get_logger(__name__)
# pylint: disable=redefined-outer-name
# We cache globals and attribute lookups, so disable this warning.
def hybrid_to_proto2(message, body):
"""Create a fresh protocol 2 message from a hybrid protocol 1/2 message."""
try:
args, kwargs = body.get('args', ()), body.get('kwargs', {})
kwargs.items # pylint: disable=pointless-statement
except KeyError:
raise InvalidTaskError('Message does not have args/kwargs')
except AttributeError:
raise InvalidTaskError(
'Task keyword arguments must be a mapping',
)
headers = {
'lang': body.get('lang'),
'task': body.get('task'),
'id': body.get('id'),
'root_id': body.get('root_id'),
'parent_id': body.get('parent_id'),
'group': body.get('group'),
'meth': body.get('meth'),
'shadow': body.get('shadow'),
'eta': body.get('eta'),
'expires': body.get('expires'),
'retries': body.get('retries', 0),
'timelimit': body.get('timelimit', (None, None)),
'argsrepr': body.get('argsrepr'),
'kwargsrepr': body.get('kwargsrepr'),
'origin': body.get('origin'),
}
headers.update(message.headers or {})
embed = {
'callbacks': body.get('callbacks'),
'errbacks': body.get('errbacks'),
'chord': body.get('chord'),
'chain': None,
}
return (args, kwargs, embed), headers, True, body.get('utc', True)
def proto1_to_proto2(message, body):
"""Convert Task message protocol 1 arguments to protocol 2.
Returns:
Tuple: of ``(body, headers, already_decoded_status, utc)``
"""
try:
args, kwargs = body.get('args', ()), body.get('kwargs', {})
kwargs.items # pylint: disable=pointless-statement
except KeyError:
raise InvalidTaskError('Message does not have args/kwargs')
except AttributeError:
raise InvalidTaskError(
'Task keyword arguments must be a mapping',
)
body.update(
argsrepr=saferepr(args),
kwargsrepr=saferepr(kwargs),
headers=message.headers,
)
try:
body['group'] = body['taskset']
except KeyError:
pass
embed = {
'callbacks': body.get('callbacks'),
'errbacks': body.get('errbacks'),
'chord': body.get('chord'),
'chain': None,
}
return (args, kwargs, embed), body, True, body.get('utc', True)
[docs]def default(task, app, consumer,
info=logger.info, error=logger.error, task_reserved=task_reserved,
to_system_tz=timezone.to_system, bytes=bytes,
proto1_to_proto2=proto1_to_proto2):
"""Default task execution strategy.
Note:
Strategies are here as an optimization, so sadly
it's not very easy to override.
"""
hostname = consumer.hostname
connection_errors = consumer.connection_errors
_does_info = logger.isEnabledFor(logging.INFO)
# task event related
# (optimized to avoid calling request.send_event)
eventer = consumer.event_dispatcher
events = eventer and eventer.enabled
send_event = eventer and eventer.send
task_sends_events = events and task.send_events
call_at = consumer.timer.call_at
apply_eta_task = consumer.apply_eta_task
rate_limits_enabled = not consumer.disable_rate_limits
get_bucket = consumer.task_buckets.__getitem__
handle = consumer.on_task_request
limit_task = consumer._limit_task
limit_post_eta = consumer._limit_post_eta
Request = symbol_by_name(task.Request)
Req = create_request_cls(Request, task, consumer.pool, hostname, eventer, app=app)
revoked_tasks = consumer.controller.state.revoked
def task_message_handler(message, body, ack, reject, callbacks,
to_timestamp=to_timestamp):
if body is None and 'args' not in message.payload:
body, headers, decoded, utc = (
message.body, message.headers, False, app.uses_utc_timezone(),
)
else:
if 'args' in message.payload:
body, headers, decoded, utc = hybrid_to_proto2(message,
message.payload)
else:
body, headers, decoded, utc = proto1_to_proto2(message, body)
req = Req(
message,
on_ack=ack, on_reject=reject, app=app, hostname=hostname,
eventer=eventer, task=task, connection_errors=connection_errors,
body=body, headers=headers, decoded=decoded, utc=utc,
)
if _does_info:
# Similar to `app.trace.info()`, we pass the formatting args as the
# `extra` kwarg for custom log handlers
context = {
'id': req.id,
'name': req.name,
'args': safe_repr(req.args),
'kwargs': safe_repr(req.kwargs),
}
info(_app_trace.LOG_RECEIVED, context, extra={'data': context})
if (req.expires or req.id in revoked_tasks) and req.revoked():
return
signals.task_received.send(sender=consumer, request=req)
if task_sends_events:
send_event(
'task-received',
uuid=req.id, name=req.name,
args=req.argsrepr, kwargs=req.kwargsrepr,
root_id=req.root_id, parent_id=req.parent_id,
retries=req.request_dict.get('retries', 0),
eta=req.eta and req.eta.isoformat(),
expires=req.expires and req.expires.isoformat(),
)
bucket = None
eta = None
if req.eta:
try:
if req.utc:
eta = to_timestamp(to_system_tz(req.eta))
else:
eta = to_timestamp(req.eta, app.timezone)
except (OverflowError, ValueError) as exc:
error("Couldn't convert ETA %r to timestamp: %r. Task: %r",
req.eta, exc, req.info(safe=True), exc_info=True)
req.reject(requeue=False)
if rate_limits_enabled:
bucket = get_bucket(task.name)
if eta and bucket:
consumer.qos.increment_eventually()
return call_at(eta, limit_post_eta, (req, bucket, 1),
priority=6)
if eta:
consumer.qos.increment_eventually()
call_at(eta, apply_eta_task, (req,), priority=6)
return task_message_handler
if bucket:
return limit_task(req, bucket, 1)
task_reserved(req)
if callbacks:
[callback(req) for callback in callbacks]
handle(req)
return task_message_handler
