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celery/celery/events/state.py
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"""In-memory representation of cluster state. | |
This module implements a data-structure 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 for example, store that in a database. | |
""" | |
import bisect | |
import sys | |
import threading | |
from collections import defaultdict | |
from collections.abc import Callable | |
from datetime import datetime | |
from decimal import Decimal | |
from itertools import islice | |
from operator import itemgetter | |
from time import time | |
from weakref import WeakSet, ref | |
from kombu.clocks import timetuple | |
from kombu.utils.objects import cached_property | |
from celery import states | |
from celery.utils.functional import LRUCache, memoize, pass1 | |
from celery.utils.log import get_logger | |
__all__ = ('Worker', 'Task', 'State', 'heartbeat_expires') | |
# pylint: disable=redefined-outer-name | |
# We cache globals and attribute lookups, so disable this warning. | |
# pylint: disable=too-many-function-args | |
# For some reason pylint thinks ._event is a method, when it's a property. | |
#: Set if running PyPy | |
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] | |
""" | |
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}>' | |
#: Mapping of task event names to task state. | |
TASK_EVENT_TO_STATE = { | |
'sent': states.PENDING, | |
'received': states.RECEIVED, | |
'started': states.STARTED, | |
'failed': states.FAILURE, | |
'retried': states.RETRY, | |
'succeeded': states.SUCCESS, | |
'revoked': states.REVOKED, | |
'rejected': states.REJECTED, | |
} | |
class CallableDefaultdict(defaultdict): | |
""":class:`~collections.defaultdict` with configurable __call__. | |
We use this for backwards compatibility in State.tasks_by_type | |
etc, which used to be a method but is now an index instead. | |
So you can do:: | |
>>> add_tasks = state.tasks_by_type['proj.tasks.add'] | |
while still supporting the method call:: | |
>>> add_tasks = list(state.tasks_by_type( | |
... 'proj.tasks.add', reverse=True)) | |
""" | |
def __init__(self, fun, *args, **kwargs): | |
self.fun = fun | |
super().__init__(*args, **kwargs) | |
def __call__(self, *args, **kwargs): | |
return self.fun(*args, **kwargs) | |
Callable.register(CallableDefaultdict) # noqa: E305 | |
@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)) | |
def heartbeat_expires(timestamp, freq=60, | |
expire_window=HEARTBEAT_EXPIRE_WINDOW, | |
Decimal=Decimal, float=float, isinstance=isinstance): | |
"""Return time when heartbeat expires.""" | |
# some json implementations returns decimal.Decimal objects, | |
# which aren't 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) | |
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): | |
res = this.__eq__(other) | |
return True if res is NotImplemented else not res | |
cls.__ne__ = __ne__ | |
def __hash__(this): | |
return hash(getattr(this, attr)) | |
cls.__hash__ = __hash__ | |
return cls | |
return _decorate_cls | |
@with_unique_field('hostname') | |
class Worker: | |
"""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: # pragma: no cover | |
__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, abs=abs, int=int, | |
insort=bisect.insort, len=len): | |
fields = fields or {} | |
for k, v in fields.items(): | |
_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 > max_drift: | |
_warn_drift(self.hostname, drift, | |
local_received, timestamp) | |
if local_received: # pragma: no cover | |
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 | |
def update(self, f, **kw): | |
d = dict(f, **kw) if kw else f | |
for k, v in d.items(): | |
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) | |
@with_unique_field('uuid') | |
class Task: | |
"""Task State.""" | |
name = received = sent = started = succeeded = failed = retried = \ | |
revoked = rejected = args = kwargs = eta = expires = retries = \ | |
worker = result = exception = timestamp = runtime = traceback = \ | |
exchange = routing_key = root_id = parent_id = client = None | |
state = states.PENDING | |
clock = 0 | |
_fields = ( | |
'uuid', 'name', 'state', 'received', 'sent', 'started', 'rejected', | |
'succeeded', 'failed', 'retried', 'revoked', 'args', 'kwargs', | |
'eta', 'expires', 'retries', 'worker', 'result', 'exception', | |
'timestamp', 'runtime', 'traceback', 'exchange', 'routing_key', | |
'clock', 'client', 'root', 'root_id', 'parent', 'parent_id', | |
'children', | |
) | |
if not PYPY: # pragma: no cover | |
__slots__ = ('__dict__', '__weakref__') | |
#: How to merge out of order events. | |
#: Disorder is detected by logical ordering (e.g., :event:`task-received` | |
#: must've 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', 'parent_id', | |
'root_id', 'retries', 'eta', 'expires', | |
), | |
} | |
#: meth:`info` displays these fields by default. | |
_info_fields = ( | |
'args', 'kwargs', 'retries', 'result', 'eta', 'runtime', | |
'expires', 'exception', 'exchange', 'routing_key', | |
'root_id', 'parent_id', | |
) | |
def __init__(self, uuid=None, cluster_state=None, children=None, **kwargs): | |
self.uuid = uuid | |
self.cluster_state = cluster_state | |
if self.cluster_state is not None: | |
self.children = WeakSet( | |
self.cluster_state.tasks.get(task_id) | |
for task_id in children or () | |
if task_id in self.cluster_state.tasks | |
) | |
else: | |
self.children = WeakSet() | |
self._serializer_handlers = { | |
'children': self._serializable_children, | |
'root': self._serializable_root, | |
'parent': self._serializable_parent, | |
} | |
if kwargs: | |
self.__dict__.update(kwargs) | |
def event(self, type_, timestamp=None, local_received=None, fields=None, | |
precedence=states.precedence, setattr=setattr, | |
task_event_to_state=TASK_EVENT_TO_STATE.get, RETRY=states.RETRY): | |
fields = fields or {} | |
# using .get is faster than catching KeyError in this case. | |
state = task_event_to_state(type_) | |
if state is not None: | |
# sets, for example, self.succeeded to the timestamp. | |
setattr(self, type_, timestamp) | |
else: | |
state = type_.upper() # custom state | |
# 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 = { | |
k: v for k, v in fields.items() if k in keep | |
} | |
else: | |
fields.update(state=state, timestamp=timestamp) | |
# update current state with info from this event. | |
self.__dict__.update(fields) | |
def info(self, fields=None, extra=None): | |
"""Information about this task suitable for on-screen display.""" | |
extra = [] if not extra else extra | |
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) | |
def as_dict(self): | |
get = object.__getattribute__ | |
handler = self._serializer_handlers.get | |
return { | |
k: handler(k, pass1)(get(self, k)) for k in self._fields | |
} | |
def _serializable_children(self, value): | |
return [task.id for task in self.children] | |
def _serializable_root(self, value): | |
return self.root_id | |
def _serializable_parent(self, value): | |
return self.parent_id | |
def __reduce__(self): | |
return _depickle_task, (self.__class__, self.as_dict()) | |
@property | |
def id(self): | |
return self.uuid | |
@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 | |
@cached_property | |
def parent(self): | |
# issue github.com/mher/flower/issues/648 | |
try: | |
return self.parent_id and self.cluster_state.tasks.data[self.parent_id] | |
except KeyError: | |
return None | |
@cached_property | |
def root(self): | |
# issue github.com/mher/flower/issues/648 | |
try: | |
return self.root_id and self.cluster_state.tasks.data[self.root_id] | |
except KeyError: | |
return None | |
class State: | |
"""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, | |
tasks_by_type=None, tasks_by_worker=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._tasks_to_resolve = {} | |
self.rebuild_taskheap() | |
# type: Mapping[TaskName, WeakSet[Task]] | |
self.tasks_by_type = CallableDefaultdict( | |
self._tasks_by_type, WeakSet) | |
self.tasks_by_type.update( | |
_deserialize_Task_WeakSet_Mapping(tasks_by_type, self.tasks)) | |
# type: Mapping[Hostname, WeakSet[Task]] | |
self.tasks_by_worker = CallableDefaultdict( | |
self._tasks_by_worker, WeakSet) | |
self.tasks_by_worker.update( | |
_deserialize_Task_WeakSet_Mapping(tasks_by_worker, self.tasks)) | |
@cached_property | |
def _event(self): | |
return self._create_dispatcher() | |
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() | |
def clear_tasks(self, ready=True): | |
with self._mutex: | |
return self._clear_tasks(ready) | |
def _clear_tasks(self, ready=True): | |
if ready: | |
in_progress = { | |
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 | |
def clear(self, ready=True): | |
with self._mutex: | |
return self._clear(ready) | |
def get_or_create_worker(self, hostname, **kwargs): | |
"""Get or create worker by hostname. | |
Returns: | |
Tuple: of ``(worker, was_created)`` pairs. | |
""" | |
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 | |
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, cluster_state=self) | |
return task, True | |
def event(self, event): | |
with self._mutex: | |
return self._event(event) | |
def task_event(self, type_, fields): | |
"""Deprecated, use :meth:`event`.""" | |
return self._event(dict(fields, type='-'.join(['task', type_])))[0] | |
def worker_event(self, type_, fields): | |
"""Deprecated, use :meth:`event`.""" | |
return self._event(dict(fields, type='-'.join(['worker', type_])))[0] | |
def _create_dispatcher(self): | |
# noqa: C901 | |
# pylint: disable=too-many-statements | |
# This code is highly optimized, but not for reusability. | |
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__ | |
get_task_by_type_set = self.tasks_by_type.__getitem__ | |
get_task_by_worker_set = self.tasks_by_worker.__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, task_created = get_task(uuid), False | |
except KeyError: | |
task = tasks[uuid] = Task(uuid, cluster_state=self) | |
task_created = True | |
if is_client_event: | |
task.client = hostname | |
else: | |
try: | |
worker = get_worker(hostname) | |
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) | |
if task_created: # add to tasks_by_type index | |
get_task_by_type_set(task_name).add(task) | |
get_task_by_worker_set(hostname).add(task) | |
if task.parent_id: | |
try: | |
parent_task = self.tasks[task.parent_id] | |
except KeyError: | |
self._add_pending_task_child(task) | |
else: | |
parent_task.children.add(task) | |
try: | |
_children = self._tasks_to_resolve.pop(uuid) | |
except KeyError: | |
pass | |
else: | |
task.children.update(_children) | |
return (task, task_created), subject | |
return _event | |
def _add_pending_task_child(self, task): | |
try: | |
ch = self._tasks_to_resolve[task.parent_id] | |
except KeyError: | |
ch = self._tasks_to_resolve[task.parent_id] = WeakSet() | |
ch.add(task) | |
def rebuild_taskheap(self, timetuple=timetuple): | |
heap = self._taskheap[:] = [ | |
timetuple(t.clock, t.timestamp, t.origin, ref(t)) | |
for t in self.tasks.values() | |
] | |
heap.sort() | |
def itertasks(self, limit=None): | |
for index, row in enumerate(self.tasks.items()): | |
yield row | |
if limit and index + 1 >= limit: | |
break | |
def tasks_by_time(self, limit=None, reverse=True): | |
"""Generator yielding tasks ordered by time. | |
Yields: | |
Tuples of ``(uuid, Task)``. | |
""" | |
_heap = self._taskheap | |
if reverse: | |
_heap = reversed(_heap) | |
seen = set() | |
for evtup in islice(_heap, 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 | |
def _tasks_by_type(self, name, limit=None, reverse=True): | |
"""Get all tasks by type. | |
This is slower than accessing :attr:`tasks_by_type`, | |
but will be ordered by time. | |
Returns: | |
Generator: giving ``(uuid, Task)`` pairs. | |
""" | |
return islice( | |
((uuid, task) for uuid, task in self.tasks_by_time(reverse=reverse) | |
if task.name == name), | |
0, limit, | |
) | |
def _tasks_by_worker(self, hostname, limit=None, reverse=True): | |
"""Get all tasks by worker. | |
Slower than accessing :attr:`tasks_by_worker`, but ordered by time. | |
""" | |
return islice( | |
((uuid, task) for uuid, task in self.tasks_by_time(reverse=reverse) | |
if task.worker.hostname == hostname), | |
0, limit, | |
) | |
def task_types(self): | |
"""Return a list of all seen task types.""" | |
return sorted(self._seen_types) | |
def alive_workers(self): | |
"""Return a list of (seemingly) alive workers.""" | |
return (w for w in self.workers.values() 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, | |
_serialize_Task_WeakSet_Mapping(self.tasks_by_type), | |
_serialize_Task_WeakSet_Mapping(self.tasks_by_worker), | |
) | |
def _serialize_Task_WeakSet_Mapping(mapping): | |
return {name: [t.id for t in tasks] for name, tasks in mapping.items()} | |
def _deserialize_Task_WeakSet_Mapping(mapping, tasks): | |
mapping = mapping or {} | |
return {name: WeakSet(tasks[i] for i in ids if i in tasks) | |
for name, ids in mapping.items()} |