This document describes the current stable version of Celery (3.1). For development docs, go here.

Source code for celery.events.state

# -*- coding: utf-8 -*-
"""
    celery.events.state
    ~~~~~~~~~~~~~~~~~~~

    This module implements a datastructure used to keep
    track of the state of a cluster of workers and the tasks
    it is working on (by consuming events).

    For every event consumed the state is updated,
    so the state represents the state of the cluster
    at the time of the last event.

    Snapshots (:mod:`celery.events.snapshot`) can be used to
    take "pictures" of this state at regular intervals
    to e.g. store that in a database.

"""
from __future__ import absolute_import

import bisect
import sys
import threading

from datetime import datetime
from decimal import Decimal
from itertools import islice
from operator import itemgetter
from time import time
from weakref import ref

from kombu.clocks import timetuple
from kombu.utils import cached_property, kwdict

from celery import states
from celery.five import class_property, items, values
from celery.utils import deprecated
from celery.utils.functional import LRUCache, memoize
from celery.utils.log import get_logger

PYPY = hasattr(sys, 'pypy_version_info')

# The window (in percentage) is added to the workers heartbeat
# frequency.  If the time between updates exceeds this window,
# then the worker is considered to be offline.
HEARTBEAT_EXPIRE_WINDOW = 200

# Max drift between event timestamp and time of event received
# before we alert that clocks may be unsynchronized.
HEARTBEAT_DRIFT_MAX = 16

DRIFT_WARNING = """\
Substantial drift from %s may mean clocks are out of sync.  Current drift is
%s seconds.  [orig: %s recv: %s]
"""

CAN_KWDICT = sys.version_info >= (2, 6, 5)

logger = get_logger(__name__)
warn = logger.warning

R_STATE = '<State: events={0.event_count} tasks={0.task_count}>'
R_WORKER = '<Worker: {0.hostname} ({0.status_string} clock:{0.clock})'
R_TASK = '<Task: {0.name}({0.uuid}) {0.state} clock:{0.clock}>'

__all__ = ['Worker', 'Task', 'State', 'heartbeat_expires']


@memoize(maxsize=1000, keyfun=lambda a, _: a[0])
def _warn_drift(hostname, drift, local_received, timestamp):
    # we use memoize here so the warning is only logged once per hostname
    warn(DRIFT_WARNING, hostname, drift,
         datetime.fromtimestamp(local_received),
         datetime.fromtimestamp(timestamp))


[docs]def heartbeat_expires(timestamp, freq=60, expire_window=HEARTBEAT_EXPIRE_WINDOW, Decimal=Decimal, float=float, isinstance=isinstance): # some json implementations returns decimal.Decimal objects, # which are not compatible with float. freq = float(freq) if isinstance(freq, Decimal) else freq if isinstance(timestamp, Decimal): timestamp = float(timestamp) return timestamp + (freq * (expire_window / 1e2))
def _depickle_task(cls, fields): return cls(**(fields if CAN_KWDICT else kwdict(fields))) def with_unique_field(attr): def _decorate_cls(cls): def __eq__(this, other): if isinstance(other, this.__class__): return getattr(this, attr) == getattr(other, attr) return NotImplemented cls.__eq__ = __eq__ def __ne__(this, other): return not this.__eq__(other) cls.__ne__ = __ne__ def __hash__(this): return hash(getattr(this, attr)) cls.__hash__ = __hash__ return cls return _decorate_cls @with_unique_field('hostname')
[docs]class Worker(object): """Worker State.""" heartbeat_max = 4 expire_window = HEARTBEAT_EXPIRE_WINDOW _fields = ('hostname', 'pid', 'freq', 'heartbeats', 'clock', 'active', 'processed', 'loadavg', 'sw_ident', 'sw_ver', 'sw_sys') if not PYPY: __slots__ = _fields + ('event', '__dict__', '__weakref__') def __init__(self, hostname=None, pid=None, freq=60, heartbeats=None, clock=0, active=None, processed=None, loadavg=None, sw_ident=None, sw_ver=None, sw_sys=None): self.hostname = hostname self.pid = pid self.freq = freq self.heartbeats = [] if heartbeats is None else heartbeats self.clock = clock or 0 self.active = active self.processed = processed self.loadavg = loadavg self.sw_ident = sw_ident self.sw_ver = sw_ver self.sw_sys = sw_sys self.event = self._create_event_handler() def __reduce__(self): return self.__class__, (self.hostname, self.pid, self.freq, self.heartbeats, self.clock, self.active, self.processed, self.loadavg, self.sw_ident, self.sw_ver, self.sw_sys) def _create_event_handler(self): _set = object.__setattr__ hbmax = self.heartbeat_max heartbeats = self.heartbeats hb_pop = self.heartbeats.pop hb_append = self.heartbeats.append def event(type_, timestamp=None, local_received=None, fields=None, max_drift=HEARTBEAT_DRIFT_MAX, items=items, abs=abs, int=int, insort=bisect.insort, len=len): fields = fields or {} for k, v in items(fields): _set(self, k, v) if type_ == 'offline': heartbeats[:] = [] else: if not local_received or not timestamp: return drift = abs(int(local_received) - int(timestamp)) if drift > HEARTBEAT_DRIFT_MAX: _warn_drift(self.hostname, drift, local_received, timestamp) if local_received: hearts = len(heartbeats) if hearts > hbmax - 1: hb_pop(0) if hearts and local_received > heartbeats[-1]: hb_append(local_received) else: insort(heartbeats, local_received) return event
[docs] def update(self, f, **kw): for k, v in items(dict(f, **kw) if kw else f): setattr(self, k, v)
def __repr__(self): return R_WORKER.format(self) @property def status_string(self): return 'ONLINE' if self.alive else 'OFFLINE' @property def heartbeat_expires(self): return heartbeat_expires(self.heartbeats[-1], self.freq, self.expire_window) @property def alive(self, nowfun=time): return bool(self.heartbeats and nowfun() < self.heartbeat_expires) @property def id(self): return '{0.hostname}.{0.pid}'.format(self) @deprecated(3.2, 3.3)
[docs] def update_heartbeat(self, received, timestamp): self.event(None, timestamp, received)
@deprecated(3.2, 3.3)
[docs] def on_online(self, timestamp=None, local_received=None, **fields): self.event('online', timestamp, local_received, fields)
@deprecated(3.2, 3.3)
[docs] def on_offline(self, timestamp=None, local_received=None, **fields): self.event('offline', timestamp, local_received, fields)
@deprecated(3.2, 3.3)
[docs] def on_heartbeat(self, timestamp=None, local_received=None, **fields): self.event('heartbeat', timestamp, local_received, fields)
@class_property def _defaults(cls): """Deprecated, to be removed in 3.3""" source = cls() return dict((k, getattr(source, k)) for k in cls._fields)
@with_unique_field('uuid')
[docs]class Task(object): """Task State.""" name = received = sent = started = succeeded = failed = retried = \ revoked = args = kwargs = eta = expires = retries = worker = result = \ exception = timestamp = runtime = traceback = exchange = \ routing_key = client = None state = states.PENDING clock = 0 _fields = ('uuid', 'name', 'state', 'received', 'sent', 'started', 'succeeded', 'failed', 'retried', 'revoked', 'args', 'kwargs', 'eta', 'expires', 'retries', 'worker', 'result', 'exception', 'timestamp', 'runtime', 'traceback', 'exchange', 'routing_key', 'clock', 'client') if not PYPY: __slots__ = ('__dict__', '__weakref__') #: How to merge out of order events. #: Disorder is detected by logical ordering (e.g. :event:`task-received` #: must have happened before a :event:`task-failed` event). #: #: A merge rule consists of a state and a list of fields to keep from #: that state. ``(RECEIVED, ('name', 'args')``, means the name and args #: fields are always taken from the RECEIVED state, and any values for #: these fields received before or after is simply ignored. merge_rules = {states.RECEIVED: ('name', 'args', 'kwargs', 'retries', 'eta', 'expires')} #: meth:`info` displays these fields by default. _info_fields = ('args', 'kwargs', 'retries', 'result', 'eta', 'runtime', 'expires', 'exception', 'exchange', 'routing_key') def __init__(self, uuid=None, **kwargs): self.uuid = uuid if kwargs: for k, v in items(kwargs): setattr(self, k, v)
[docs] def event(self, type_, timestamp=None, local_received=None, fields=None, precedence=states.precedence, items=items, dict=dict, PENDING=states.PENDING, RECEIVED=states.RECEIVED, STARTED=states.STARTED, FAILURE=states.FAILURE, RETRY=states.RETRY, SUCCESS=states.SUCCESS, REVOKED=states.REVOKED): fields = fields or {} if type_ == 'sent': state, self.sent = PENDING, timestamp elif type_ == 'received': state, self.received = RECEIVED, timestamp elif type_ == 'started': state, self.started = STARTED, timestamp elif type_ == 'failed': state, self.failed = FAILURE, timestamp elif type_ == 'retried': state, self.retried = RETRY, timestamp elif type_ == 'succeeded': state, self.succeeded = SUCCESS, timestamp elif type_ == 'revoked': state, self.revoked = REVOKED, timestamp else: state = type_.upper() # note that precedence here is reversed # see implementation in celery.states.state.__lt__ if state != RETRY and self.state != RETRY and \ precedence(state) > precedence(self.state): # this state logically happens-before the current state, so merge. keep = self.merge_rules.get(state) if keep is not None: fields = dict( (k, v) for k, v in items(fields) if k in keep ) for key, value in items(fields): setattr(self, key, value) else: self.state = state self.timestamp = timestamp for key, value in items(fields): setattr(self, key, value)
[docs] def info(self, fields=None, extra=[]): """Information about this task suitable for on-screen display.""" fields = self._info_fields if fields is None else fields def _keys(): for key in list(fields) + list(extra): value = getattr(self, key, None) if value is not None: yield key, value return dict(_keys())
def __repr__(self): return R_TASK.format(self)
[docs] def as_dict(self): get = object.__getattribute__ return dict( (k, get(self, k)) for k in self._fields )
def __reduce__(self): return _depickle_task, (self.__class__, self.as_dict()) @property def origin(self): return self.client if self.worker is None else self.worker.id @property def ready(self): return self.state in states.READY_STATES @deprecated(3.2, 3.3)
[docs] def on_sent(self, timestamp=None, **fields): self.event('sent', timestamp, fields)
@deprecated(3.2, 3.3)
[docs] def on_received(self, timestamp=None, **fields): self.event('received', timestamp, fields)
@deprecated(3.2, 3.3)
[docs] def on_started(self, timestamp=None, **fields): self.event('started', timestamp, fields)
@deprecated(3.2, 3.3)
[docs] def on_failed(self, timestamp=None, **fields): self.event('failed', timestamp, fields)
@deprecated(3.2, 3.3)
[docs] def on_retried(self, timestamp=None, **fields): self.event('retried', timestamp, fields)
@deprecated(3.2, 3.3)
[docs] def on_succeeded(self, timestamp=None, **fields): self.event('succeeded', timestamp, fields)
@deprecated(3.2, 3.3)
[docs] def on_revoked(self, timestamp=None, **fields): self.event('revoked', timestamp, fields)
@deprecated(3.2, 3.3)
[docs] def on_unknown_event(self, shortype, timestamp=None, **fields): self.event(shortype, timestamp, fields)
@deprecated(3.2, 3.3)
[docs] def update(self, state, timestamp, fields, _state=states.state, RETRY=states.RETRY): return self.event(state, timestamp, None, fields)
@deprecated(3.2, 3.3)
[docs] def merge(self, state, timestamp, fields): keep = self.merge_rules.get(state) if keep is not None: fields = dict((k, v) for k, v in items(fields) if k in keep) for key, value in items(fields): setattr(self, key, value)
@class_property def _defaults(cls): """Deprecated, to be removed in 3.3.""" source = cls() return dict((k, getattr(source, k)) for k in source._fields)
[docs]class State(object): """Records clusters state.""" Worker = Worker Task = Task event_count = 0 task_count = 0 heap_multiplier = 4 def __init__(self, callback=None, workers=None, tasks=None, taskheap=None, max_workers_in_memory=5000, max_tasks_in_memory=10000, on_node_join=None, on_node_leave=None): self.event_callback = callback self.workers = (LRUCache(max_workers_in_memory) if workers is None else workers) self.tasks = (LRUCache(max_tasks_in_memory) if tasks is None else tasks) self._taskheap = [] if taskheap is None else taskheap self.max_workers_in_memory = max_workers_in_memory self.max_tasks_in_memory = max_tasks_in_memory self.on_node_join = on_node_join self.on_node_leave = on_node_leave self._mutex = threading.Lock() self.handlers = {} self._seen_types = set() self.rebuild_taskheap() @cached_property def _event(self): return self._create_dispatcher()
[docs] def freeze_while(self, fun, *args, **kwargs): clear_after = kwargs.pop('clear_after', False) with self._mutex: try: return fun(*args, **kwargs) finally: if clear_after: self._clear()
[docs] def clear_tasks(self, ready=True): with self._mutex: return self._clear_tasks(ready)
def _clear_tasks(self, ready=True): if ready: in_progress = dict( (uuid, task) for uuid, task in self.itertasks() if task.state not in states.READY_STATES) self.tasks.clear() self.tasks.update(in_progress) else: self.tasks.clear() self._taskheap[:] = [] def _clear(self, ready=True): self.workers.clear() self._clear_tasks(ready) self.event_count = 0 self.task_count = 0
[docs] def clear(self, ready=True): with self._mutex: return self._clear(ready)
[docs] def get_or_create_worker(self, hostname, **kwargs): """Get or create worker by hostname. Return tuple of ``(worker, was_created)``. """ try: worker = self.workers[hostname] if kwargs: worker.update(kwargs) return worker, False except KeyError: worker = self.workers[hostname] = self.Worker( hostname, **kwargs) return worker, True
[docs] def get_or_create_task(self, uuid): """Get or create task by uuid.""" try: return self.tasks[uuid], False except KeyError: task = self.tasks[uuid] = self.Task(uuid) return task, True
[docs] def event(self, event): with self._mutex: return self._event(event)
[docs] def task_event(self, type_, fields): """Deprecated, use :meth:`event`.""" return self._event(dict(fields, type='-'.join(['task', type_])))[0]
[docs] def worker_event(self, type_, fields): """Deprecated, use :meth:`event`.""" return self._event(dict(fields, type='-'.join(['worker', type_])))[0]
def _create_dispatcher(self): get_handler = self.handlers.__getitem__ event_callback = self.event_callback wfields = itemgetter('hostname', 'timestamp', 'local_received') tfields = itemgetter('uuid', 'hostname', 'timestamp', 'local_received', 'clock') taskheap = self._taskheap th_append = taskheap.append th_pop = taskheap.pop # Removing events from task heap is an O(n) operation, # so easier to just account for the common number of events # for each task (PENDING->RECEIVED->STARTED->final) #: an O(n) operation max_events_in_heap = self.max_tasks_in_memory * self.heap_multiplier add_type = self._seen_types.add on_node_join, on_node_leave = self.on_node_join, self.on_node_leave tasks, Task = self.tasks, self.Task workers, Worker = self.workers, self.Worker # avoid updating LRU entry at getitem get_worker, get_task = workers.data.__getitem__, tasks.data.__getitem__ def _event(event, timetuple=timetuple, KeyError=KeyError, insort=bisect.insort, created=True): self.event_count += 1 if event_callback: event_callback(self, event) group, _, subject = event['type'].partition('-') try: handler = get_handler(group) except KeyError: pass else: return handler(subject, event), subject if group == 'worker': try: hostname, timestamp, local_received = wfields(event) except KeyError: pass else: is_offline = subject == 'offline' try: worker, created = get_worker(hostname), False except KeyError: if is_offline: worker, created = Worker(hostname), False else: worker = workers[hostname] = Worker(hostname) worker.event(subject, timestamp, local_received, event) if on_node_join and (created or subject == 'online'): on_node_join(worker) if on_node_leave and is_offline: on_node_leave(worker) workers.pop(hostname, None) return (worker, created), subject elif group == 'task': (uuid, hostname, timestamp, local_received, clock) = tfields(event) # task-sent event is sent by client, not worker is_client_event = subject == 'sent' try: task, created = get_task(uuid), False except KeyError: task = tasks[uuid] = Task(uuid) if is_client_event: task.client = hostname else: try: worker, created = get_worker(hostname), False except KeyError: worker = workers[hostname] = Worker(hostname) task.worker = worker if worker is not None and local_received: worker.event(None, local_received, timestamp) origin = hostname if is_client_event else worker.id # remove oldest event if exceeding the limit. heaps = len(taskheap) if heaps + 1 > max_events_in_heap: th_pop(0) # most events will be dated later than the previous. timetup = timetuple(clock, timestamp, origin, ref(task)) if heaps and timetup > taskheap[-1]: th_append(timetup) else: insort(taskheap, timetup) if subject == 'received': self.task_count += 1 task.event(subject, timestamp, local_received, event) task_name = task.name if task_name is not None: add_type(task_name) return (task, created), subject return _event
[docs] def rebuild_taskheap(self, timetuple=timetuple): heap = self._taskheap[:] = [ timetuple(t.clock, t.timestamp, t.origin, ref(t)) for t in values(self.tasks) ] heap.sort()
[docs] def itertasks(self, limit=None): for index, row in enumerate(items(self.tasks)): yield row if limit and index + 1 >= limit: break
[docs] def tasks_by_time(self, limit=None): """Generator giving tasks ordered by time, in ``(uuid, Task)`` tuples.""" seen = set() for evtup in islice(reversed(self._taskheap), 0, limit): task = evtup[3]() if task is not None: uuid = task.uuid if uuid not in seen: yield uuid, task seen.add(uuid)
tasks_by_timestamp = tasks_by_time
[docs] def tasks_by_type(self, name, limit=None): """Get all tasks by type. Return a list of ``(uuid, Task)`` tuples. """ return islice( ((uuid, task) for uuid, task in self.tasks_by_time() if task.name == name), 0, limit, )
[docs] def tasks_by_worker(self, hostname, limit=None): """Get all tasks by worker. """ return islice( ((uuid, task) for uuid, task in self.tasks_by_time() if task.worker.hostname == hostname), 0, limit, )
[docs] def task_types(self): """Return a list of all seen task types.""" return sorted(self._seen_types)
[docs] def alive_workers(self): """Return a list of (seemingly) alive workers.""" return [w for w in values(self.workers) if w.alive]
def __repr__(self): return R_STATE.format(self) def __reduce__(self): return self.__class__, ( self.event_callback, self.workers, self.tasks, None, self.max_workers_in_memory, self.max_tasks_in_memory, self.on_node_join, self.on_node_leave, )