import asyncio
from collections import defaultdict, deque, OrderedDict
from collections.abc import Mapping, Set
from datetime import timedelta
from functools import partial
import itertools
import json
import logging
import math
from numbers import Number
import operator
import os
import pickle
import random
import warnings
import weakref
import psutil
import sortedcontainers
try:
from cytoolz import frequencies, merge, pluck, merge_sorted, first
except ImportError:
from toolz import frequencies, merge, pluck, merge_sorted, first
from toolz import valmap, second, compose, groupby
from tornado import gen
from tornado.gen import Return
from tornado.ioloop import IOLoop
import dask
from .batched import BatchedSend
from .comm import (
normalize_address,
resolve_address,
get_address_host,
unparse_host_port,
)
from .comm.addressing import address_from_user_args
from .core import rpc, connect, send_recv, clean_exception, CommClosedError
from .diagnostics.plugin import SchedulerPlugin
from . import profile
from .metrics import time
from .node import ServerNode
from .preloading import preload_modules
from .proctitle import setproctitle
from .security import Security
from .utils import (
All,
ignoring,
get_fileno_limit,
log_errors,
key_split,
validate_key,
no_default,
parse_timedelta,
parse_bytes,
PeriodicCallback,
shutting_down,
)
from .utils_comm import scatter_to_workers, gather_from_workers
from .utils_perf import enable_gc_diagnosis, disable_gc_diagnosis
from .publish import PublishExtension
from .queues import QueueExtension
from .recreate_exceptions import ReplayExceptionScheduler
from .lock import LockExtension
from .pubsub import PubSubSchedulerExtension
from .stealing import WorkStealing
from .variable import VariableExtension
logger = logging.getLogger(__name__)
LOG_PDB = dask.config.get("distributed.admin.pdb-on-err")
DEFAULT_DATA_SIZE = dask.config.get("distributed.scheduler.default-data-size")
DEFAULT_EXTENSIONS = [
LockExtension,
PublishExtension,
ReplayExceptionScheduler,
QueueExtension,
VariableExtension,
PubSubSchedulerExtension,
]
if dask.config.get("distributed.scheduler.work-stealing"):
DEFAULT_EXTENSIONS.append(WorkStealing)
ALL_TASK_STATES = {"released", "waiting", "no-worker", "processing", "erred", "memory"}
[docs]class ClientState(object):
"""
A simple object holding information about a client.
.. attribute:: client_key: str
A unique identifier for this client. This is generally an opaque
string generated by the client itself.
.. attribute:: wants_what: {TaskState}
A set of tasks this client wants kept in memory, so that it can
download its result when desired. This is the reverse mapping of
:class:`TaskState.who_wants`.
Tasks are typically removed from this set when the corresponding
object in the client's space (for example a ``Future`` or a Dask
collection) gets garbage-collected.
"""
__slots__ = ("client_key", "wants_what", "last_seen")
def __init__(self, client):
self.client_key = client
self.wants_what = set()
self.last_seen = time()
def __repr__(self):
return "<Client %r>" % (self.client_key,)
def __str__(self):
return self.client_key
[docs]class WorkerState(object):
"""
A simple object holding information about a worker.
.. attribute:: address
This worker's unique key. This can be its connected address
(such as ``'tcp://127.0.0.1:8891'``) or an alias (such as ``'alice'``).
.. attribute:: processing: {TaskState: cost}
A dictionary of tasks that have been submitted to this worker.
Each task state is asssociated with the expected cost in seconds
of running that task, summing both the task's expected computation
time and the expected communication time of its result.
Multiple tasks may be submitted to a worker in advance and the worker
will run them eventually, depending on its execution resources
(but see :doc:`work-stealing`).
All the tasks here are in the "processing" state.
This attribute is kept in sync with :attr:`TaskState.processing_on`.
.. attribute:: has_what: {TaskState}
The set of tasks which currently reside on this worker.
All the tasks here are in the "memory" state.
This is the reverse mapping of :class:`TaskState.who_has`.
.. attribute:: nbytes: int
The total memory size, in bytes, used by the tasks this worker
holds in memory (i.e. the tasks in this worker's :attr:`has_what`).
.. attribute:: nthreads: int
The number of CPU threads made available on this worker.
.. attribute:: resources: {str: Number}
The available resources on this worker like ``{'gpu': 2}``.
These are abstract quantities that constrain certain tasks from
running at the same time on this worker.
.. attribute:: used_resources: {str: Number}
The sum of each resource used by all tasks allocated to this worker.
The numbers in this dictionary can only be less or equal than
those in this worker's :attr:`resources`.
.. attribute:: occupancy: Number
The total expected runtime, in seconds, of all tasks currently
processing on this worker. This is the sum of all the costs in
this worker's :attr:`processing` dictionary.
.. attribute:: status: str
The current status of the worker, either ``'running'`` or ``'closed'``
.. attribute:: nanny: str
Address of the associated Nanny, if present
.. attribute:: last_seen: Number
The last time we received a heartbeat from this worker, in local
scheduler time.
.. attribute:: actors: {TaskState}
A set of all TaskStates on this worker that are actors. This only
includes those actors whose state actually lives on this worker, not
actors to which this worker has a reference.
"""
# XXX need a state field to signal active/removed?
__slots__ = (
"actors",
"address",
"extra",
"has_what",
"last_seen",
"local_directory",
"memory_limit",
"metrics",
"name",
"nanny",
"nbytes",
"nthreads",
"occupancy",
"pid",
"processing",
"resources",
"services",
"status",
"time_delay",
"used_resources",
)
def __init__(
self,
address=None,
pid=0,
name=None,
nthreads=0,
memory_limit=0,
local_directory=None,
services=None,
nanny=None,
extra=None,
):
self.address = address
self.pid = pid
self.name = name
self.nthreads = nthreads
self.memory_limit = memory_limit
self.local_directory = local_directory
self.services = services or {}
self.nanny = nanny
self.status = "running"
self.nbytes = 0
self.occupancy = 0
self.metrics = {}
self.last_seen = 0
self.time_delay = 0
self.actors = set()
self.has_what = set()
self.processing = {}
self.resources = {}
self.used_resources = {}
self.extra = extra or {}
@property
def host(self):
return get_address_host(self.address)
def clean(self):
""" Return a version of this object that is appropriate for serialization """
ws = WorkerState(
address=self.address,
pid=self.pid,
name=self.name,
nthreads=self.nthreads,
memory_limit=self.memory_limit,
local_directory=self.local_directory,
services=self.services,
nanny=self.nanny,
extra=self.extra,
)
ws.processing = {ts.key for ts in self.processing}
return ws
def __repr__(self):
return "<Worker %r, memory: %d, processing: %d>" % (
self.address,
len(self.has_what),
len(self.processing),
)
def __str__(self):
return self.address
def identity(self):
return {
"type": "Worker",
"id": self.name,
"host": self.host,
"resources": self.resources,
"local_directory": self.local_directory,
"name": self.name,
"nthreads": self.nthreads,
"memory_limit": self.memory_limit,
"last_seen": self.last_seen,
"services": self.services,
"metrics": self.metrics,
"nanny": self.nanny,
**self.extra,
}
@property
def ncores(self):
warnings.warn("WorkerState.ncores has moved to WorkerState.nthreads")
return self.nthreads
[docs]class TaskState(object):
"""
A simple object holding information about a task.
.. attribute:: key: str
The key is the unique identifier of a task, generally formed
from the name of the function, followed by a hash of the function
and arguments, like ``'inc-ab31c010444977004d656610d2d421ec'``.
.. attribute:: prefix: str
The key prefix, used in certain calculations to get an estimate
of the task's duration based on the duration of other tasks in the
same "family" (for example ``'inc'``).
.. attribute:: run_spec: object
A specification of how to run the task. The type and meaning of this
value is opaque to the scheduler, as it is only interpreted by the
worker to which the task is sent for executing.
As a special case, this attribute may also be ``None``, in which case
the task is "pure data" (such as, for example, a piece of data loaded
in the scheduler using :meth:`Client.scatter`). A "pure data" task
cannot be computed again if its value is lost.
.. attribute:: priority: tuple
The priority provides each task with a relative ranking which is used
to break ties when many tasks are being considered for execution.
This ranking is generally a 2-item tuple. The first (and dominant)
item corresponds to when it was submitted. Generally, earlier tasks
take precedence. The second item is determined by the client, and is
a way to prioritize tasks within a large graph that may be important,
such as if they are on the critical path, or good to run in order to
release many dependencies. This is explained further in
:doc:`Scheduling Policy <scheduling-policies>`.
.. attribute:: state: str
This task's current state. Valid states include ``released``,
``waiting``, ``no-worker``, ``processing``, ``memory``, ``erred``
and ``forgotten``. If it is ``forgotten``, the task isn't stored
in the ``tasks`` dictionary anymore and will probably disappear
soon from memory.
.. attribute:: dependencies: {TaskState}
The set of tasks this task depends on for proper execution. Only
tasks still alive are listed in this set. If, for whatever reason,
this task also depends on a forgotten task, the
:attr:`has_lost_dependencies` flag is set.
A task can only be executed once all its dependencies have already
been successfully executed and have their result stored on at least
one worker. This is tracked by progressively draining the
:attr:`waiting_on` set.
.. attribute:: dependents: {TaskState}
The set of tasks which depend on this task. Only tasks still alive
are listed in this set.
This is the reverse mapping of :attr:`dependencies`.
.. attribute:: has_lost_dependencies: bool
Whether any of the dependencies of this task has been forgotten.
For memory consumption reasons, forgotten tasks are not kept in
memory even though they may have dependent tasks. When a task is
forgotten, therefore, each of its dependents has their
:attr:`has_lost_dependencies` attribute set to ``True``.
If :attr:`has_lost_dependencies` is true, this task cannot go
into the "processing" state anymore.
.. attribute:: waiting_on: {TaskState}
The set of tasks this task is waiting on *before* it can be executed.
This is always a subset of :attr:`dependencies`. Each time one of the
dependencies has finished processing, it is removed from the
:attr:`waiting_on` set.
Once :attr:`waiting_on` becomes empty, this task can move from the
"waiting" state to the "processing" state (unless one of the
dependencies errored out, in which case this task is instead
marked "erred").
.. attribute:: waiters: {TaskState}
The set of tasks which need this task to remain alive. This is always
a subset of :attr:`dependents`. Each time one of the dependents
has finished processing, it is removed from the :attr:`waiters`
set.
Once both :attr:`waiters` and :attr:`who_wants` become empty, this
task can be released (if it has a non-empty :attr:`run_spec`) or
forgotten (otherwise) by the scheduler, and by any workers
in :attr:`who_has`.
.. note:: Counter-intuitively, :attr:`waiting_on` and
:attr:`waiters` are not reverse mappings of each other.
.. attribute:: who_wants: {ClientState}
The set of clients who want this task's result to remain alive.
This is the reverse mapping of :attr:`ClientState.wants_what`.
When a client submits a graph to the scheduler it also specifies
which output tasks it desires, such that their results are not released
from memory.
Once a task has finished executing (i.e. moves into the "memory"
or "erred" state), the clients in :attr:`who_wants` are notified.
Once both :attr:`waiters` and :attr:`who_wants` become empty, this
task can be released (if it has a non-empty :attr:`run_spec`) or
forgotten (otherwise) by the scheduler, and by any workers
in :attr:`who_has`.
.. attribute:: who_has: {WorkerState}
The set of workers who have this task's result in memory.
It is non-empty iff the task is in the "memory" state. There can be
more than one worker in this set if, for example, :meth:`Client.scatter`
or :meth:`Client.replicate` was used.
This is the reverse mapping of :attr:`WorkerState.has_what`.
.. attribute:: processing_on: WorkerState (or None)
If this task is in the "processing" state, which worker is currently
processing it. Otherwise this is ``None``.
This attribute is kept in sync with :attr:`WorkerState.processing`.
.. attribute:: retries: int
The number of times this task can automatically be retried in case
of failure. If a task fails executing (the worker returns with
an error), its :attr:`retries` attribute is checked. If it is
equal to 0, the task is marked "erred". If it is greater than 0,
the :attr:`retries` attribute is decremented and execution is
attempted again.
.. attribute:: nbytes: int (or None)
The number of bytes, as determined by ``sizeof``, of the result
of a finished task. This number is used for diagnostics and to
help prioritize work.
.. attribute:: type: str
The type of the object as a string. Only present for tasks that have
been computed.
.. attribute:: exception: object
If this task failed executing, the exception object is stored here.
Otherwise this is ``None``.
.. attribute:: traceback: object
If this task failed executing, the traceback object is stored here.
Otherwise this is ``None``.
.. attribute:: exception_blame: TaskState (or None)
If this task or one of its dependencies failed executing, the
failed task is stored here (possibly itself). Otherwise this
is ``None``.
.. attribute:: suspicious: int
The number of times this task has been involved in a worker death.
Some tasks may cause workers to die (such as calling ``os._exit(0)``).
When a worker dies, all of the tasks on that worker are reassigned
to others. This combination of behaviors can cause a bad task to
catastrophically destroy all workers on the cluster, one after
another. Whenever a worker dies, we mark each task currently
processing on that worker (as recorded by
:attr:`WorkerState.processing`) as suspicious.
If a task is involved in three deaths (or some other fixed constant)
then we mark the task as ``erred``.
.. attribute:: host_restrictions: {hostnames}
A set of hostnames where this task can be run (or ``None`` if empty).
Usually this is empty unless the task has been specifically restricted
to only run on certain hosts. A hostname may correspond to one or
several connected workers.
.. attribute:: worker_restrictions: {worker addresses}
A set of complete worker addresses where this can be run (or ``None``
if empty). Usually this is empty unless the task has been specifically
restricted to only run on certain workers.
Note this is tracking worker addresses, not worker states, since
the specific workers may not be connected at this time.
.. attribute:: resource_restrictions: {resource: quantity}
Resources required by this task, such as ``{'gpu': 1}`` or
``{'memory': 1e9}`` (or ``None`` if empty). These are user-defined
names and are matched against the contents of each
:attr:`WorkerState.resources` dictionary.
.. attribute:: loose_restrictions: bool
If ``False``, each of :attr:`host_restrictions`,
:attr:`worker_restrictions` and :attr:`resource_restrictions` is
a hard constraint: if no worker is available satisfying those
restrictions, the task cannot go into the "processing" state and
will instead go into the "no-worker" state.
If ``True``, the above restrictions are mere preferences: if no worker
is available satisfying those restrictions, the task can still go
into the "processing" state and be sent for execution to another
connected worker.
.. attribute: actor: bool
Whether or not this task is an Actor.
"""
__slots__ = (
# === General description ===
"actor",
# Key name
"key",
# Key prefix (see key_split())
"prefix",
# How to run the task (None if pure data)
"run_spec",
# Alive dependents and dependencies
"dependencies",
"dependents",
# Compute priority
"priority",
# Restrictions
"host_restrictions",
"worker_restrictions", # not WorkerStates but addresses
"resource_restrictions",
"loose_restrictions",
# === Task state ===
"state",
# Whether some dependencies were forgotten
"has_lost_dependencies",
# If in 'waiting' state, which tasks need to complete
# before we can run
"waiting_on",
# If in 'waiting' or 'processing' state, which tasks needs us
# to complete before they can run
"waiters",
# In in 'processing' state, which worker we are processing on
"processing_on",
# If in 'memory' state, Which workers have us
"who_has",
# Which clients want us
"who_wants",
"exception",
"traceback",
"exception_blame",
"suspicious",
"retries",
"nbytes",
"type",
)
def __init__(self, key, run_spec):
self.key = key
self.prefix = key_split(key)
self.run_spec = run_spec
self.state = None
self.exception = self.traceback = self.exception_blame = None
self.suspicious = self.retries = 0
self.nbytes = None
self.priority = None
self.who_wants = set()
self.dependencies = set()
self.dependents = set()
self.waiting_on = set()
self.waiters = set()
self.who_has = set()
self.processing_on = None
self.has_lost_dependencies = False
self.host_restrictions = None
self.worker_restrictions = None
self.resource_restrictions = None
self.loose_restrictions = False
self.actor = None
self.type = None
def get_nbytes(self):
nbytes = self.nbytes
return nbytes if nbytes is not None else DEFAULT_DATA_SIZE
def set_nbytes(self, nbytes):
old_nbytes = self.nbytes
diff = nbytes - (old_nbytes or 0)
for ws in self.who_has:
ws.nbytes += diff
self.nbytes = nbytes
def __repr__(self):
return "<Task %r %s>" % (self.key, self.state)
def validate(self):
try:
for cs in self.who_wants:
assert isinstance(cs, ClientState), (repr(cs), self.who_wants)
for ws in self.who_has:
assert isinstance(ws, WorkerState), (repr(ws), self.who_has)
for ts in self.dependencies:
assert isinstance(ts, TaskState), (repr(ts), self.dependencies)
for ts in self.dependents:
assert isinstance(ts, TaskState), (repr(ts), self.dependents)
validate_task_state(self)
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
class _StateLegacyMapping(Mapping):
"""
A mapping interface mimicking the former Scheduler state dictionaries.
"""
def __init__(self, states, accessor):
self._states = states
self._accessor = accessor
def __iter__(self):
return iter(self._states)
def __len__(self):
return len(self._states)
def __getitem__(self, key):
return self._accessor(self._states[key])
def __repr__(self):
return "%s(%s)" % (self.__class__, dict(self))
class _OptionalStateLegacyMapping(_StateLegacyMapping):
"""
Similar to _StateLegacyMapping, but a false-y value is interpreted
as a missing key.
"""
# For tasks etc.
def __iter__(self):
accessor = self._accessor
for k, v in self._states.items():
if accessor(v):
yield k
def __len__(self):
accessor = self._accessor
return sum(bool(accessor(v)) for v in self._states.values())
def __getitem__(self, key):
v = self._accessor(self._states[key])
if v:
return v
else:
raise KeyError
class _StateLegacySet(Set):
"""
Similar to _StateLegacyMapping, but exposes a set containing
all values with a true value.
"""
# For loose_restrictions
def __init__(self, states, accessor):
self._states = states
self._accessor = accessor
def __iter__(self):
return (k for k, v in self._states.items() if self._accessor(v))
def __len__(self):
return sum(map(bool, map(self._accessor, self._states.values())))
def __contains__(self, k):
st = self._states.get(k)
return st is not None and bool(self._accessor(st))
def __repr__(self):
return "%s(%s)" % (self.__class__, set(self))
def _legacy_task_key_set(tasks):
"""
Transform a set of task states into a set of task keys.
"""
return {ts.key for ts in tasks}
def _legacy_client_key_set(clients):
"""
Transform a set of client states into a set of client keys.
"""
return {cs.client_key for cs in clients}
def _legacy_worker_key_set(workers):
"""
Transform a set of worker states into a set of worker keys.
"""
return {ws.address for ws in workers}
def _legacy_task_key_dict(task_dict):
"""
Transform a dict of {task state: value} into a dict of {task key: value}.
"""
return {ts.key: value for ts, value in task_dict.items()}
def _task_key_or_none(task):
return task.key if task is not None else None
[docs]class Scheduler(ServerNode):
""" Dynamic distributed task scheduler
The scheduler tracks the current state of workers, data, and computations.
The scheduler listens for events and responds by controlling workers
appropriately. It continuously tries to use the workers to execute an ever
growing dask graph.
All events are handled quickly, in linear time with respect to their input
(which is often of constant size) and generally within a millisecond. To
accomplish this the scheduler tracks a lot of state. Every operation
maintains the consistency of this state.
The scheduler communicates with the outside world through Comm objects.
It maintains a consistent and valid view of the world even when listening
to several clients at once.
A Scheduler is typically started either with the ``dask-scheduler``
executable::
$ dask-scheduler
Scheduler started at 127.0.0.1:8786
Or within a LocalCluster a Client starts up without connection
information::
>>> c = Client() # doctest: +SKIP
>>> c.cluster.scheduler # doctest: +SKIP
Scheduler(...)
Users typically do not interact with the scheduler directly but rather with
the client object ``Client``.
**State**
The scheduler contains the following state variables. Each variable is
listed along with what it stores and a brief description.
* **tasks:** ``{task key: TaskState}``
Tasks currently known to the scheduler
* **unrunnable:** ``{TaskState}``
Tasks in the "no-worker" state
* **workers:** ``{worker key: WorkerState}``
Workers currently connected to the scheduler
* **idle:** ``{WorkerState}``:
Set of workers that are not fully utilized
* **saturated:** ``{WorkerState}``:
Set of workers that are not over-utilized
* **host_info:** ``{hostname: dict}``:
Information about each worker host
* **clients:** ``{client key: ClientState}``
Clients currently connected to the scheduler
* **services:** ``{str: port}``:
Other services running on this scheduler, like Bokeh
* **loop:** ``IOLoop``:
The running Tornado IOLoop
* **client_comms:** ``{client key: Comm}``
For each client, a Comm object used to receive task requests and
report task status updates.
* **stream_comms:** ``{worker key: Comm}``
For each worker, a Comm object from which we both accept stimuli and
report results
* **task_duration:** ``{key-prefix: time}``
Time we expect certain functions to take, e.g. ``{'sum': 0.25}``
"""
default_port = 8786
_instances = weakref.WeakSet()
def __init__(
self,
loop=None,
delete_interval="500ms",
synchronize_worker_interval="60s",
services=None,
service_kwargs=None,
allowed_failures=None,
extensions=None,
validate=False,
scheduler_file=None,
security=None,
worker_ttl=None,
idle_timeout=None,
interface=None,
host=None,
port=0,
protocol=None,
dashboard_address=None,
preload=None,
preload_argv=(),
**kwargs
):
self._setup_logging(logger)
# Attributes
if allowed_failures is None:
allowed_failures = dask.config.get("distributed.scheduler.allowed-failures")
self.allowed_failures = allowed_failures
self.validate = validate
self.status = None
self.proc = psutil.Process()
self.delete_interval = parse_timedelta(delete_interval, default="ms")
self.synchronize_worker_interval = parse_timedelta(
synchronize_worker_interval, default="ms"
)
self.digests = None
self.service_specs = services or {}
self.service_kwargs = service_kwargs or {}
self.services = {}
self.scheduler_file = scheduler_file
worker_ttl = worker_ttl or dask.config.get("distributed.scheduler.worker-ttl")
self.worker_ttl = parse_timedelta(worker_ttl) if worker_ttl else None
idle_timeout = idle_timeout or dask.config.get(
"distributed.scheduler.idle-timeout"
)
if idle_timeout:
self.idle_timeout = parse_timedelta(idle_timeout)
else:
self.idle_timeout = None
self.time_started = time()
self.bandwidth = parse_bytes(dask.config.get("distributed.scheduler.bandwidth"))
if not preload:
preload = dask.config.get("distributed.scheduler.preload")
if not preload_argv:
preload_argv = dask.config.get("distributed.scheduler.preload-argv")
self.preload = preload
self.preload_argv = preload_argv
self.security = security or Security()
assert isinstance(self.security, Security)
self.connection_args = self.security.get_connection_args("scheduler")
self.listen_args = self.security.get_listen_args("scheduler")
if dashboard_address is not None:
try:
from distributed.dashboard import BokehScheduler
except ImportError:
logger.debug("To start diagnostics web server please install Bokeh")
else:
self.service_specs[("dashboard", dashboard_address)] = (
BokehScheduler,
(service_kwargs or {}).get("dashboard", {}),
)
# Communication state
self.loop = loop or IOLoop.current()
self.client_comms = dict()
self.stream_comms = dict()
self._worker_coroutines = []
self._ipython_kernel = None
# Task state
self.tasks = dict()
for old_attr, new_attr, wrap in [
("priority", "priority", None),
("dependencies", "dependencies", _legacy_task_key_set),
("dependents", "dependents", _legacy_task_key_set),
("retries", "retries", None),
]:
func = operator.attrgetter(new_attr)
if wrap is not None:
func = compose(wrap, func)
setattr(self, old_attr, _StateLegacyMapping(self.tasks, func))
for old_attr, new_attr, wrap in [
("nbytes", "nbytes", None),
("who_wants", "who_wants", _legacy_client_key_set),
("who_has", "who_has", _legacy_worker_key_set),
("waiting", "waiting_on", _legacy_task_key_set),
("waiting_data", "waiters", _legacy_task_key_set),
("rprocessing", "processing_on", None),
("host_restrictions", "host_restrictions", None),
("worker_restrictions", "worker_restrictions", None),
("resource_restrictions", "resource_restrictions", None),
("suspicious_tasks", "suspicious", None),
("exceptions", "exception", None),
("tracebacks", "traceback", None),
("exceptions_blame", "exception_blame", _task_key_or_none),
]:
func = operator.attrgetter(new_attr)
if wrap is not None:
func = compose(wrap, func)
setattr(self, old_attr, _OptionalStateLegacyMapping(self.tasks, func))
for old_attr, new_attr, wrap in [
("loose_restrictions", "loose_restrictions", None)
]:
func = operator.attrgetter(new_attr)
if wrap is not None:
func = compose(wrap, func)
setattr(self, old_attr, _StateLegacySet(self.tasks, func))
self.generation = 0
self._last_client = None
self._last_time = 0
self.unrunnable = set()
self.n_tasks = 0
self.task_metadata = dict()
self.datasets = dict()
# Prefix-keyed containers
self.task_duration = {prefix: 0.00001 for prefix in fast_tasks}
self.unknown_durations = defaultdict(set)
# Client state
self.clients = dict()
for old_attr, new_attr, wrap in [
("wants_what", "wants_what", _legacy_task_key_set)
]:
func = operator.attrgetter(new_attr)
if wrap is not None:
func = compose(wrap, func)
setattr(self, old_attr, _StateLegacyMapping(self.clients, func))
self.clients["fire-and-forget"] = ClientState("fire-and-forget")
# Worker state
self.workers = sortedcontainers.SortedDict()
for old_attr, new_attr, wrap in [
("nthreads", "nthreads", None),
("worker_bytes", "nbytes", None),
("worker_resources", "resources", None),
("used_resources", "used_resources", None),
("occupancy", "occupancy", None),
("worker_info", "metrics", None),
("processing", "processing", _legacy_task_key_dict),
("has_what", "has_what", _legacy_task_key_set),
]:
func = operator.attrgetter(new_attr)
if wrap is not None:
func = compose(wrap, func)
setattr(self, old_attr, _StateLegacyMapping(self.workers, func))
self.idle = sortedcontainers.SortedSet(key=operator.attrgetter("address"))
self.saturated = set()
self.total_nthreads = 0
self.total_occupancy = 0
self.host_info = defaultdict(dict)
self.resources = defaultdict(dict)
self.aliases = dict()
self._task_state_collections = [self.unrunnable]
self._worker_collections = [
self.workers,
self.host_info,
self.resources,
self.aliases,
]
self.extensions = {}
self.plugins = []
self.transition_log = deque(
maxlen=dask.config.get("distributed.scheduler.transition-log-length")
)
self.log = deque(
maxlen=dask.config.get("distributed.scheduler.transition-log-length")
)
self.worker_plugins = []
worker_handlers = {
"task-finished": self.handle_task_finished,
"task-erred": self.handle_task_erred,
"release": self.handle_release_data,
"release-worker-data": self.release_worker_data,
"add-keys": self.add_keys,
"missing-data": self.handle_missing_data,
"long-running": self.handle_long_running,
"reschedule": self.reschedule,
"keep-alive": lambda *args, **kwargs: None,
}
client_handlers = {
"update-graph": self.update_graph,
"client-desires-keys": self.client_desires_keys,
"update-data": self.update_data,
"report-key": self.report_on_key,
"client-releases-keys": self.client_releases_keys,
"heartbeat-client": self.client_heartbeat,
"close-client": self.remove_client,
"restart": self.restart,
}
self.handlers = {
"register-client": self.add_client,
"scatter": self.scatter,
"register-worker": self.add_worker,
"unregister": self.remove_worker,
"gather": self.gather,
"cancel": self.stimulus_cancel,
"retry": self.stimulus_retry,
"feed": self.feed,
"terminate": self.close,
"broadcast": self.broadcast,
"proxy": self.proxy,
"ncores": self.get_ncores,
"has_what": self.get_has_what,
"who_has": self.get_who_has,
"processing": self.get_processing,
"call_stack": self.get_call_stack,
"profile": self.get_profile,
"logs": self.get_logs,
"worker_logs": self.get_worker_logs,
"nbytes": self.get_nbytes,
"versions": self.versions,
"add_keys": self.add_keys,
"rebalance": self.rebalance,
"replicate": self.replicate,
"start_ipython": self.start_ipython,
"run_function": self.run_function,
"update_data": self.update_data,
"set_resources": self.add_resources,
"retire_workers": self.retire_workers,
"get_metadata": self.get_metadata,
"set_metadata": self.set_metadata,
"heartbeat_worker": self.heartbeat_worker,
"get_task_status": self.get_task_status,
"get_task_stream": self.get_task_stream,
"register_worker_plugin": self.register_worker_plugin,
"adaptive_target": self.adaptive_target,
"workers_to_close": self.workers_to_close,
"subscribe_worker_status": self.subscribe_worker_status,
}
self._transitions = {
("released", "waiting"): self.transition_released_waiting,
("waiting", "released"): self.transition_waiting_released,
("waiting", "processing"): self.transition_waiting_processing,
("waiting", "memory"): self.transition_waiting_memory,
("processing", "released"): self.transition_processing_released,
("processing", "memory"): self.transition_processing_memory,
("processing", "erred"): self.transition_processing_erred,
("no-worker", "released"): self.transition_no_worker_released,
("no-worker", "waiting"): self.transition_no_worker_waiting,
("released", "forgotten"): self.transition_released_forgotten,
("memory", "forgotten"): self.transition_memory_forgotten,
("erred", "forgotten"): self.transition_released_forgotten,
("erred", "released"): self.transition_erred_released,
("memory", "released"): self.transition_memory_released,
("released", "erred"): self.transition_released_erred,
}
connection_limit = get_fileno_limit() / 2
self._start_address = address_from_user_args(
host=host,
port=port,
interface=interface,
protocol=protocol,
security=security,
default_port=self.default_port,
)
super(Scheduler, self).__init__(
handlers=self.handlers,
stream_handlers=merge(worker_handlers, client_handlers),
io_loop=self.loop,
connection_limit=connection_limit,
deserialize=False,
connection_args=self.connection_args,
**kwargs
)
if self.worker_ttl:
pc = PeriodicCallback(self.check_worker_ttl, self.worker_ttl, io_loop=loop)
self.periodic_callbacks["worker-ttl"] = pc
if self.idle_timeout:
pc = PeriodicCallback(self.check_idle, self.idle_timeout / 4, io_loop=loop)
self.periodic_callbacks["idle-timeout"] = pc
if extensions is None:
extensions = DEFAULT_EXTENSIONS
for ext in extensions:
ext(self)
setproctitle("dask-scheduler [not started]")
Scheduler._instances.add(self)
##################
# Administration #
##################
def __repr__(self):
return '<Scheduler: "%s" processes: %d cores: %d>' % (
self.address,
len(self.workers),
self.total_nthreads,
)
[docs] def identity(self, comm=None):
""" Basic information about ourselves and our cluster """
d = {
"type": type(self).__name__,
"id": str(self.id),
"address": self.address,
"services": {key: v.port for (key, v) in self.services.items()},
"workers": {
worker.address: worker.identity() for worker in self.workers.values()
},
}
return d
[docs] def get_worker_service_addr(self, worker, service_name, protocol=False):
"""
Get the (host, port) address of the named service on the *worker*.
Returns None if the service doesn't exist.
Parameters
----------
worker : address
service_name : str
Common services include 'bokeh' and 'nanny'
protocol : boolean
Whether or not to include a full address with protocol (True)
or just a (host, port) pair
"""
ws = self.workers[worker]
port = ws.services.get(service_name)
if port is None:
return None
elif protocol:
return "%(protocol)s://%(host)s:%(port)d" % {
"protocol": ws.address.split("://")[0],
"host": ws.host,
"port": port,
}
else:
return ws.host, port
[docs] async def start(self):
""" Clear out old state and restart all running coroutines """
enable_gc_diagnosis()
self.clear_task_state()
with ignoring(AttributeError):
for c in self._worker_coroutines:
c.cancel()
if self.status != "running":
self.listen(self._start_address, listen_args=self.listen_args)
self.ip = get_address_host(self.listen_address)
listen_ip = self.ip
if listen_ip == "0.0.0.0":
listen_ip = ""
if self._start_address.startswith("inproc://"):
listen_ip = "localhost"
# Services listen on all addresses
self.start_services(listen_ip)
self.status = "running"
logger.info(" Scheduler at: %25s", self.address)
for k, v in self.services.items():
logger.info("%11s at: %25s", k, "%s:%d" % (listen_ip, v.port))
self.loop.add_callback(self.reevaluate_occupancy)
if self.scheduler_file:
with open(self.scheduler_file, "w") as f:
json.dump(self.identity(), f, indent=2)
fn = self.scheduler_file # remove file when we close the process
def del_scheduler_file():
if os.path.exists(fn):
os.remove(fn)
weakref.finalize(self, del_scheduler_file)
preload_modules(self.preload, parameter=self, argv=self.preload_argv)
self.start_periodic_callbacks()
setproctitle("dask-scheduler [%s]" % (self.address,))
return self
[docs] async def close(self, comm=None, fast=False, close_workers=False):
""" Send cleanup signal to all coroutines then wait until finished
See Also
--------
Scheduler.cleanup
"""
if self.status.startswith("clos"):
await self.finished()
return
self.status = "closing"
logger.info("Scheduler closing...")
setproctitle("dask-scheduler [closing]")
if close_workers:
await self.broadcast(msg={"op": "close_gracefully"}, nanny=True)
for worker in self.workers:
self.worker_send(worker, {"op": "close"})
for i in range(20): # wait a second for send signals to clear
if self.workers:
await gen.sleep(0.05)
else:
break
for pc in self.periodic_callbacks.values():
pc.stop()
self.periodic_callbacks.clear()
self.stop_services()
for ext in self.extensions.values():
with ignoring(AttributeError):
ext.teardown()
logger.info("Scheduler closing all comms")
futures = []
for w, comm in list(self.stream_comms.items()):
if not comm.closed():
comm.send({"op": "close", "report": False})
comm.send({"op": "close-stream"})
with ignoring(AttributeError):
futures.append(comm.close())
for future in futures: # TODO: do all at once
await future
for comm in self.client_comms.values():
comm.abort()
self.rpc.close()
self.status = "closed"
self.stop()
await super(Scheduler, self).close()
setproctitle("dask-scheduler [closed]")
disable_gc_diagnosis()
[docs] async def close_worker(self, stream=None, worker=None, safe=None):
""" Remove a worker from the cluster
This both removes the worker from our local state and also sends a
signal to the worker to shut down. This works regardless of whether or
not the worker has a nanny process restarting it
"""
logger.info("Closing worker %s", worker)
with log_errors():
self.log_event(worker, {"action": "close-worker"})
nanny_addr = self.workers[worker].nanny
address = nanny_addr or worker
self.worker_send(worker, {"op": "close", "report": False})
self.remove_worker(address=worker, safe=safe)
###########
# Stimuli #
###########
def heartbeat_worker(
self,
comm=None,
address=None,
resolve_address=True,
now=None,
resources=None,
host_info=None,
metrics=None,
):
address = self.coerce_address(address, resolve_address)
address = normalize_address(address)
if address not in self.workers:
return {"status": "missing"}
host = get_address_host(address)
local_now = time()
now = now or time()
metrics = metrics or {}
host_info = host_info or {}
self.host_info[host]["last-seen"] = local_now
frac = 1 / 20 / len(self.workers)
try:
self.bandwidth = self.bandwidth * (1 - frac) + metrics["bandwidth"] * frac
except KeyError:
pass
ws = self.workers[address]
ws.last_seen = time()
if metrics:
ws.metrics = metrics
if host_info:
self.host_info[host].update(host_info)
delay = time() - now
ws.time_delay = delay
if resources:
self.add_resources(worker=address, resources=resources)
self.log_event(address, merge({"action": "heartbeat"}, metrics))
return {
"status": "OK",
"time": time(),
"heartbeat-interval": heartbeat_interval(len(self.workers)),
}
[docs] async def add_worker(
self,
comm=None,
address=None,
keys=(),
nthreads=None,
name=None,
resolve_address=True,
nbytes=None,
types=None,
now=None,
resources=None,
host_info=None,
memory_limit=None,
metrics=None,
pid=0,
services=None,
local_directory=None,
nanny=None,
extra=None,
):
""" Add a new worker to the cluster """
with log_errors():
address = self.coerce_address(address, resolve_address)
address = normalize_address(address)
host = get_address_host(address)
ws = self.workers.get(address)
if ws is not None:
raise ValueError("Worker already exists %s" % address)
self.workers[address] = ws = WorkerState(
address=address,
pid=pid,
nthreads=nthreads,
memory_limit=memory_limit,
name=name,
local_directory=local_directory,
services=services,
nanny=nanny,
extra=extra,
)
if name in self.aliases:
msg = {
"status": "error",
"message": "name taken, %s" % name,
"time": time(),
}
if comm:
await comm.write(msg)
return
if "addresses" not in self.host_info[host]:
self.host_info[host].update({"addresses": set(), "nthreads": 0})
self.host_info[host]["addresses"].add(address)
self.host_info[host]["nthreads"] += nthreads
self.total_nthreads += nthreads
self.aliases[name] = address
response = self.heartbeat_worker(
address=address,
resolve_address=resolve_address,
now=now,
resources=resources,
host_info=host_info,
metrics=metrics,
)
# Do not need to adjust self.total_occupancy as self.occupancy[ws] cannot exist before this.
self.check_idle_saturated(ws)
# for key in keys: # TODO
# self.mark_key_in_memory(key, [address])
self.stream_comms[address] = BatchedSend(interval="5ms", loop=self.loop)
if ws.nthreads > len(ws.processing):
self.idle.add(ws)
for plugin in self.plugins[:]:
try:
plugin.add_worker(scheduler=self, worker=address)
except Exception as e:
logger.exception(e)
if nbytes:
for key in nbytes:
ts = self.tasks.get(key)
if ts is not None and ts.state in ("processing", "waiting"):
recommendations = self.transition(
key,
"memory",
worker=address,
nbytes=nbytes[key],
typename=types[key],
)
self.transitions(recommendations)
recommendations = {}
for ts in list(self.unrunnable):
valid = self.valid_workers(ts)
if valid is True or ws in valid:
recommendations[ts.key] = "waiting"
if recommendations:
self.transitions(recommendations)
self.log_event(address, {"action": "add-worker"})
self.log_event("all", {"action": "add-worker", "worker": address})
logger.info("Register %s", str(address))
if comm:
await comm.write(
{
"status": "OK",
"time": time(),
"heartbeat-interval": heartbeat_interval(len(self.workers)),
"worker-plugins": self.worker_plugins,
}
)
await self.handle_worker(comm=comm, worker=address)
[docs] def update_graph(
self,
client=None,
tasks=None,
keys=None,
dependencies=None,
restrictions=None,
priority=None,
loose_restrictions=None,
resources=None,
submitting_task=None,
retries=None,
user_priority=0,
actors=None,
fifo_timeout=0,
):
"""
Add new computations to the internal dask graph
This happens whenever the Client calls submit, map, get, or compute.
"""
start = time()
fifo_timeout = parse_timedelta(fifo_timeout)
keys = set(keys)
if len(tasks) > 1:
self.log_event(
["all", client], {"action": "update_graph", "count": len(tasks)}
)
# Remove aliases
for k in list(tasks):
if tasks[k] is k:
del tasks[k]
dependencies = dependencies or {}
n = 0
while len(tasks) != n: # walk through new tasks, cancel any bad deps
n = len(tasks)
for k, deps in list(dependencies.items()):
if any(
dep not in self.tasks and dep not in tasks for dep in deps
): # bad key
logger.info("User asked for computation on lost data, %s", k)
del tasks[k]
del dependencies[k]
if k in keys:
keys.remove(k)
self.report({"op": "cancelled-key", "key": k}, client=client)
self.client_releases_keys(keys=[k], client=client)
# Remove any self-dependencies (happens on test_publish_bag() and others)
for k, v in dependencies.items():
deps = set(v)
if k in deps:
deps.remove(k)
dependencies[k] = deps
# Avoid computation that is already finished
already_in_memory = set() # tasks that are already done
for k, v in dependencies.items():
if v and k in self.tasks and self.tasks[k].state in ("memory", "erred"):
already_in_memory.add(k)
if already_in_memory:
dependents = dask.core.reverse_dict(dependencies)
stack = list(already_in_memory)
done = set(already_in_memory)
while stack: # remove unnecessary dependencies
key = stack.pop()
ts = self.tasks[key]
try:
deps = dependencies[key]
except KeyError:
deps = self.dependencies[key]
for dep in deps:
if dep in dependents:
child_deps = dependents[dep]
else:
child_deps = self.dependencies[dep]
if all(d in done for d in child_deps):
if dep in self.tasks:
done.add(dep)
stack.append(dep)
for d in done:
tasks.pop(d, None)
dependencies.pop(d, None)
# Get or create task states
stack = list(keys)
touched_keys = set()
touched_tasks = []
while stack:
k = stack.pop()
if k in touched_keys:
continue
# XXX Have a method get_task_state(self, k) ?
ts = self.tasks.get(k)
if ts is None:
ts = self.tasks[k] = TaskState(k, tasks.get(k))
ts.state = "released"
elif not ts.run_spec:
ts.run_spec = tasks.get(k)
touched_keys.add(k)
touched_tasks.append(ts)
stack.extend(dependencies.get(k, ()))
self.client_desires_keys(keys=keys, client=client)
# Add dependencies
for key, deps in dependencies.items():
ts = self.tasks.get(key)
if ts is None or ts.dependencies:
continue
for dep in deps:
dts = self.tasks[dep]
ts.dependencies.add(dts)
dts.dependents.add(ts)
# Compute priorities
if isinstance(user_priority, Number):
user_priority = {k: user_priority for k in tasks}
# Add actors
if actors is True:
actors = list(keys)
for actor in actors or []:
self.tasks[actor].actor = True
priority = priority or dask.order.order(
tasks
) # TODO: define order wrt old graph
if submitting_task: # sub-tasks get better priority than parent tasks
ts = self.tasks.get(submitting_task)
if ts is not None:
generation = ts.priority[0] - 0.01
else: # super-task already cleaned up
generation = self.generation
elif self._last_time + fifo_timeout < start:
self.generation += 1 # older graph generations take precedence
generation = self.generation
self._last_time = start
else:
generation = self.generation
for key in set(priority) & touched_keys:
ts = self.tasks[key]
if ts.priority is None:
ts.priority = (-(user_priority.get(key, 0)), generation, priority[key])
# Ensure all runnables have a priority
runnables = [ts for ts in touched_tasks if ts.run_spec]
for ts in runnables:
if ts.priority is None and ts.run_spec:
ts.priority = (self.generation, 0)
if restrictions:
# *restrictions* is a dict keying task ids to lists of
# restriction specifications (either worker names or addresses)
for k, v in restrictions.items():
if v is None:
continue
ts = self.tasks.get(k)
if ts is None:
continue
ts.host_restrictions = set()
ts.worker_restrictions = set()
for w in v:
try:
w = self.coerce_address(w)
except ValueError:
# Not a valid address, but perhaps it's a hostname
ts.host_restrictions.add(w)
else:
ts.worker_restrictions.add(w)
if loose_restrictions:
for k in loose_restrictions:
ts = self.tasks[k]
ts.loose_restrictions = True
if resources:
for k, v in resources.items():
if v is None:
continue
assert isinstance(v, dict)
ts = self.tasks.get(k)
if ts is None:
continue
ts.resource_restrictions = v
if retries:
for k, v in retries.items():
assert isinstance(v, int)
ts = self.tasks.get(k)
if ts is None:
continue
ts.retries = v
# Compute recommendations
recommendations = OrderedDict()
for ts in sorted(runnables, key=operator.attrgetter("priority"), reverse=True):
if ts.state == "released" and ts.run_spec:
recommendations[ts.key] = "waiting"
for ts in touched_tasks:
for dts in ts.dependencies:
if dts.exception_blame:
ts.exception_blame = dts.exception_blame
recommendations[ts.key] = "erred"
break
for plugin in self.plugins[:]:
try:
plugin.update_graph(
self,
client=client,
tasks=tasks,
keys=keys,
restrictions=restrictions or {},
dependencies=dependencies,
priority=priority,
loose_restrictions=loose_restrictions,
resources=resources,
)
except Exception as e:
logger.exception(e)
self.transitions(recommendations)
for ts in touched_tasks:
if ts.state in ("memory", "erred"):
self.report_on_key(ts.key, client=client)
end = time()
if self.digests is not None:
self.digests["update-graph-duration"].add(end - start)
# TODO: balance workers
[docs] def stimulus_task_finished(self, key=None, worker=None, **kwargs):
""" Mark that a task has finished execution on a particular worker """
logger.debug("Stimulus task finished %s, %s", key, worker)
ts = self.tasks.get(key)
if ts is None:
return {}
ws = self.workers[worker]
if ts.state == "processing":
recommendations = self.transition(key, "memory", worker=worker, **kwargs)
if ts.state == "memory":
assert ws in ts.who_has
else:
logger.debug(
"Received already computed task, worker: %s, state: %s"
", key: %s, who_has: %s",
worker,
ts.state,
key,
ts.who_has,
)
if ws not in ts.who_has:
self.worker_send(worker, {"op": "release-task", "key": key})
recommendations = {}
return recommendations
[docs] def stimulus_task_erred(
self, key=None, worker=None, exception=None, traceback=None, **kwargs
):
""" Mark that a task has erred on a particular worker """
logger.debug("Stimulus task erred %s, %s", key, worker)
ts = self.tasks.get(key)
if ts is None:
return {}
if ts.state == "processing":
retries = ts.retries
if retries > 0:
ts.retries = retries - 1
recommendations = self.transition(key, "waiting")
else:
recommendations = self.transition(
key,
"erred",
cause=key,
exception=exception,
traceback=traceback,
worker=worker,
**kwargs
)
else:
recommendations = {}
return recommendations
[docs] def stimulus_missing_data(
self, cause=None, key=None, worker=None, ensure=True, **kwargs
):
""" Mark that certain keys have gone missing. Recover. """
with log_errors():
logger.debug("Stimulus missing data %s, %s", key, worker)
ts = self.tasks.get(key)
if ts is None or ts.state == "memory":
return {}
cts = self.tasks.get(cause)
recommendations = OrderedDict()
if cts is not None and cts.state == "memory": # couldn't find this
for ws in cts.who_has: # TODO: this behavior is extreme
ws.has_what.remove(cts)
ws.nbytes -= cts.get_nbytes()
cts.who_has.clear()
recommendations[cause] = "released"
if key:
recommendations[key] = "released"
self.transitions(recommendations)
if self.validate:
assert cause not in self.who_has
return {}
def stimulus_retry(self, comm=None, keys=None, client=None):
logger.info("Client %s requests to retry %d keys", client, len(keys))
if client:
self.log_event(client, {"action": "retry", "count": len(keys)})
stack = list(keys)
seen = set()
roots = []
while stack:
key = stack.pop()
seen.add(key)
erred_deps = [
dts.key for dts in self.tasks[key].dependencies if dts.state == "erred"
]
if erred_deps:
stack.extend(erred_deps)
else:
roots.append(key)
recommendations = {key: "waiting" for key in roots}
self.transitions(recommendations)
if self.validate:
for key in seen:
assert not self.tasks[key].exception_blame
return tuple(seen)
[docs] def remove_worker(self, comm=None, address=None, safe=False, close=True):
"""
Remove worker from cluster
We do this when a worker reports that it plans to leave or when it
appears to be unresponsive. This may send its tasks back to a released
state.
"""
with log_errors():
if self.status == "closed":
return
if address not in self.workers:
return "already-removed"
address = self.coerce_address(address)
host = get_address_host(address)
ws = self.workers[address]
self.log_event(
["all", address],
{
"action": "remove-worker",
"worker": address,
"processing-tasks": dict(ws.processing),
},
)
logger.info("Remove worker %s", address)
if close:
with ignoring(AttributeError, CommClosedError):
self.stream_comms[address].send({"op": "close", "report": False})
self.remove_resources(address)
self.host_info[host]["nthreads"] -= ws.nthreads
self.host_info[host]["addresses"].remove(address)
self.total_nthreads -= ws.nthreads
if not self.host_info[host]["addresses"]:
del self.host_info[host]
self.rpc.remove(address)
del self.stream_comms[address]
del self.aliases[ws.name]
self.idle.discard(ws)
self.saturated.discard(ws)
del self.workers[address]
ws.status = "closed"
self.total_occupancy -= ws.occupancy
recommendations = OrderedDict()
for ts in list(ws.processing):
k = ts.key
recommendations[k] = "released"
if not safe:
ts.suspicious += 1
if ts.suspicious > self.allowed_failures:
del recommendations[k]
e = pickle.dumps(
KilledWorker(task=k, last_worker=ws.clean()), -1
)
r = self.transition(k, "erred", exception=e, cause=k)
recommendations.update(r)
for ts in ws.has_what:
ts.who_has.remove(ws)
if not ts.who_has:
if ts.run_spec:
recommendations[ts.key] = "released"
else: # pure data
recommendations[ts.key] = "forgotten"
ws.has_what.clear()
self.transitions(recommendations)
for plugin in self.plugins[:]:
try:
plugin.remove_worker(scheduler=self, worker=address)
except Exception as e:
logger.exception(e)
if not self.workers:
logger.info("Lost all workers")
def remove_worker_from_events():
# If the worker isn't registered anymore after the delay, remove from events
if address not in self.workers and address in self.events:
del self.events[address]
cleanup_delay = parse_timedelta(
dask.config.get("distributed.scheduler.events-cleanup-delay")
)
self.loop.call_later(cleanup_delay, remove_worker_from_events)
logger.debug("Removed worker %s", address)
return "OK"
[docs] def stimulus_cancel(self, comm, keys=None, client=None, force=False):
""" Stop execution on a list of keys """
logger.info("Client %s requests to cancel %d keys", client, len(keys))
if client:
self.log_event(
client, {"action": "cancel", "count": len(keys), "force": force}
)
for key in keys:
self.cancel_key(key, client, force=force)
[docs] def cancel_key(self, key, client, retries=5, force=False):
""" Cancel a particular key and all dependents """
# TODO: this should be converted to use the transition mechanism
ts = self.tasks.get(key)
try:
cs = self.clients[client]
except KeyError:
return
if ts is None or not ts.who_wants: # no key yet, lets try again in a moment
if retries:
self.loop.add_future(
gen.sleep(0.2), lambda _: self.cancel_key(key, client, retries - 1)
)
return
if force or ts.who_wants == {cs}: # no one else wants this key
for dts in list(ts.dependents):
self.cancel_key(dts.key, client, force=force)
logger.info("Scheduler cancels key %s. Force=%s", key, force)
self.report({"op": "cancelled-key", "key": key})
clients = list(ts.who_wants) if force else [cs]
for c in clients:
self.client_releases_keys(keys=[key], client=c.client_key)
def client_desires_keys(self, keys=None, client=None):
cs = self.clients.get(client)
if cs is None:
# For publish, queues etc.
cs = self.clients[client] = ClientState(client)
for k in keys:
ts = self.tasks.get(k)
if ts is None:
# For publish, queues etc.
ts = self.tasks[k] = TaskState(k, None)
ts.state = "released"
ts.who_wants.add(cs)
cs.wants_what.add(ts)
if ts.state in ("memory", "erred"):
self.report_on_key(k, client=client)
[docs] def client_releases_keys(self, keys=None, client=None):
""" Remove keys from client desired list """
logger.debug("Client %s releases keys: %s", client, keys)
cs = self.clients[client]
tasks2 = set()
for key in list(keys):
ts = self.tasks.get(key)
if ts is not None and ts in cs.wants_what:
cs.wants_what.remove(ts)
s = ts.who_wants
s.remove(cs)
if not s:
tasks2.add(ts)
recommendations = {}
for ts in tasks2:
if not ts.dependents:
# No live dependents, can forget
recommendations[ts.key] = "forgotten"
elif ts.state != "erred" and not ts.waiters:
recommendations[ts.key] = "released"
self.transitions(recommendations)
[docs] def client_heartbeat(self, client=None):
""" Handle heartbeats from Client """
self.clients[client].last_seen = time()
###################
# Task Validation #
###################
def validate_released(self, key):
ts = self.tasks[key]
assert ts.state == "released"
assert not ts.waiters
assert not ts.waiting_on
assert not ts.who_has
assert not ts.processing_on
assert not any(ts in dts.waiters for dts in ts.dependencies)
assert ts not in self.unrunnable
def validate_waiting(self, key):
ts = self.tasks[key]
assert ts.waiting_on
assert not ts.who_has
assert not ts.processing_on
assert ts not in self.unrunnable
for dts in ts.dependencies:
# We are waiting on a dependency iff it's not stored
assert bool(dts.who_has) + (dts in ts.waiting_on) == 1
assert ts in dts.waiters # XXX even if dts.who_has?
def validate_processing(self, key):
ts = self.tasks[key]
assert not ts.waiting_on
ws = ts.processing_on
assert ws
assert ts in ws.processing
assert not ts.who_has
for dts in ts.dependencies:
assert dts.who_has
assert ts in dts.waiters
def validate_memory(self, key):
ts = self.tasks[key]
assert ts.who_has
assert not ts.processing_on
assert not ts.waiting_on
assert ts not in self.unrunnable
for dts in ts.dependents:
assert (dts in ts.waiters) == (dts.state in ("waiting", "processing"))
assert ts not in dts.waiting_on
def validate_no_worker(self, key):
ts = self.tasks[key]
assert ts in self.unrunnable
assert not ts.waiting_on
assert ts in self.unrunnable
assert not ts.processing_on
assert not ts.who_has
for dts in ts.dependencies:
assert dts.who_has
def validate_erred(self, key):
ts = self.tasks[key]
assert ts.exception_blame
assert not ts.who_has
def validate_key(self, key, ts=None):
try:
if ts is None:
ts = self.tasks.get(key)
if ts is None:
logger.debug("Key lost: %s", key)
else:
ts.validate()
try:
func = getattr(self, "validate_" + ts.state.replace("-", "_"))
except AttributeError:
logger.error(
"self.validate_%s not found", ts.state.replace("-", "_")
)
else:
func(key)
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def validate_state(self, allow_overlap=False):
validate_state(self.tasks, self.workers, self.clients)
if not (set(self.workers) == set(self.stream_comms)):
raise ValueError("Workers not the same in all collections")
for w, ws in self.workers.items():
assert isinstance(w, str), (type(w), w)
assert isinstance(ws, WorkerState), (type(ws), ws)
assert ws.address == w
if not ws.processing:
assert not ws.occupancy
assert ws in self.idle
for k, ts in self.tasks.items():
assert isinstance(ts, TaskState), (type(ts), ts)
assert ts.key == k
self.validate_key(k, ts)
for c, cs in self.clients.items():
# client=None is often used in tests...
assert c is None or isinstance(c, str), (type(c), c)
assert isinstance(cs, ClientState), (type(cs), cs)
assert cs.client_key == c
a = {w: ws.nbytes for w, ws in self.workers.items()}
b = {
w: sum(ts.get_nbytes() for ts in ws.has_what)
for w, ws in self.workers.items()
}
assert a == b, (a, b)
actual_total_occupancy = 0
for worker, ws in self.workers.items():
assert abs(sum(ws.processing.values()) - ws.occupancy) < 1e-8
actual_total_occupancy += ws.occupancy
assert abs(actual_total_occupancy - self.total_occupancy) < 1e-8, (
actual_total_occupancy,
self.total_occupancy,
)
###################
# Manage Messages #
###################
[docs] def report(self, msg, ts=None, client=None):
"""
Publish updates to all listening Queues and Comms
If the message contains a key then we only send the message to those
comms that care about the key.
"""
if client is not None:
try:
comm = self.client_comms[client]
comm.send(msg)
except CommClosedError:
if self.status == "running":
logger.critical("Tried writing to closed comm: %s", msg)
except KeyError:
pass
if ts is None and "key" in msg:
ts = self.tasks.get(msg["key"])
if ts is None:
# Notify all clients
comms = self.client_comms.values()
else:
# Notify clients interested in key
comms = [
self.client_comms[c.client_key]
for c in ts.who_wants
if c.client_key in self.client_comms
]
for c in comms:
try:
c.send(msg)
# logger.debug("Scheduler sends message to client %s", msg)
except CommClosedError:
if self.status == "running":
logger.critical("Tried writing to closed comm: %s", msg)
[docs] async def add_client(self, comm, client=None):
""" Add client to network
We listen to all future messages from this Comm.
"""
assert client is not None
comm.name = "Scheduler->Client"
logger.info("Receive client connection: %s", client)
self.log_event(["all", client], {"action": "add-client", "client": client})
self.clients[client] = ClientState(client)
try:
bcomm = BatchedSend(interval="2ms", loop=self.loop)
bcomm.start(comm)
self.client_comms[client] = bcomm
bcomm.send({"op": "stream-start"})
try:
await self.handle_stream(comm=comm, extra={"client": client})
finally:
self.remove_client(client=client)
logger.debug("Finished handling client %s", client)
finally:
if not comm.closed():
self.client_comms[client].send({"op": "stream-closed"})
try:
if not shutting_down():
await self.client_comms[client].close()
del self.client_comms[client]
if self.status == "running":
logger.info("Close client connection: %s", client)
except TypeError: # comm becomes None during GC
pass
[docs] def remove_client(self, client=None):
""" Remove client from network """
if self.status == "running":
logger.info("Remove client %s", client)
self.log_event(["all", client], {"action": "remove-client", "client": client})
try:
cs = self.clients[client]
except KeyError:
# XXX is this a legitimate condition?
pass
else:
self.client_releases_keys(
keys=[ts.key for ts in cs.wants_what], client=cs.client_key
)
del self.clients[client]
def remove_client_from_events():
# If the client isn't registered anymore after the delay, remove from events
if client not in self.clients and client in self.events:
del self.events[client]
cleanup_delay = parse_timedelta(
dask.config.get("distributed.scheduler.events-cleanup-delay")
)
self.loop.call_later(cleanup_delay, remove_client_from_events)
[docs] def send_task_to_worker(self, worker, key):
""" Send a single computational task to a worker """
try:
ts = self.tasks[key]
msg = {
"op": "compute-task",
"key": key,
"priority": ts.priority,
"duration": self.get_task_duration(ts),
}
if ts.resource_restrictions:
msg["resource_restrictions"] = ts.resource_restrictions
if ts.actor:
msg["actor"] = True
deps = ts.dependencies
if deps:
msg["who_has"] = {
dep.key: [ws.address for ws in dep.who_has] for dep in deps
}
msg["nbytes"] = {dep.key: dep.nbytes for dep in deps}
if self.validate and deps:
assert all(msg["who_has"].values())
task = ts.run_spec
if type(task) is dict:
msg.update(task)
else:
msg["task"] = task
self.worker_send(worker, msg)
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def handle_uncaught_error(self, **msg):
logger.exception(clean_exception(**msg)[1])
def handle_task_finished(self, key=None, worker=None, **msg):
if worker not in self.workers:
return
validate_key(key)
r = self.stimulus_task_finished(key=key, worker=worker, **msg)
self.transitions(r)
def handle_task_erred(self, key=None, **msg):
r = self.stimulus_task_erred(key=key, **msg)
self.transitions(r)
def handle_release_data(self, key=None, worker=None, client=None, **msg):
ts = self.tasks.get(key)
if ts is None:
return
ws = self.workers[worker]
if ts.processing_on is not ws:
return
r = self.stimulus_missing_data(key=key, ensure=False, **msg)
self.transitions(r)
def handle_missing_data(self, key=None, errant_worker=None, **kwargs):
logger.debug("handle missing data key=%s worker=%s", key, errant_worker)
self.log.append(("missing", key, errant_worker))
ts = self.tasks.get(key)
if ts is None or not ts.who_has:
return
if errant_worker in self.workers:
ws = self.workers[errant_worker]
if ws in ts.who_has:
ts.who_has.remove(ws)
ws.has_what.remove(ts)
ws.nbytes -= ts.get_nbytes()
if not ts.who_has:
if ts.run_spec:
self.transitions({key: "released"})
else:
self.transitions({key: "forgotten"})
def release_worker_data(self, stream=None, keys=None, worker=None):
ws = self.workers[worker]
tasks = {self.tasks[k] for k in keys}
removed_tasks = tasks & ws.has_what
ws.has_what -= removed_tasks
recommendations = {}
for ts in removed_tasks:
ws.nbytes -= ts.get_nbytes()
wh = ts.who_has
wh.remove(ws)
if not wh:
recommendations[ts.key] = "released"
if recommendations:
self.transitions(recommendations)
[docs] def handle_long_running(self, key=None, worker=None, compute_duration=None):
""" A task has seceded from the thread pool
We stop the task from being stolen in the future, and change task
duration accounting as if the task has stopped.
"""
ts = self.tasks[key]
if "stealing" in self.extensions:
self.extensions["stealing"].remove_key_from_stealable(ts)
ws = ts.processing_on
if ws is None:
logger.debug("Received long-running signal from duplicate task. Ignoring.")
return
if compute_duration:
prefix = ts.prefix
old_duration = self.task_duration.get(prefix, 0)
new_duration = compute_duration
if not old_duration:
avg_duration = new_duration
else:
avg_duration = 0.5 * old_duration + 0.5 * new_duration
self.task_duration[prefix] = avg_duration
ws.occupancy -= ws.processing[ts]
self.total_occupancy -= ws.processing[ts]
ws.processing[ts] = 0
self.check_idle_saturated(ws)
[docs] async def handle_worker(self, comm=None, worker=None):
"""
Listen to responses from a single worker
This is the main loop for scheduler-worker interaction
See Also
--------
Scheduler.handle_client: Equivalent coroutine for clients
"""
comm.name = "Scheduler connection to worker"
worker_comm = self.stream_comms[worker]
worker_comm.start(comm)
logger.info("Starting worker compute stream, %s", worker)
try:
await self.handle_stream(comm=comm, extra={"worker": worker})
finally:
if worker in self.stream_comms:
worker_comm.abort()
self.remove_worker(address=worker)
[docs] def add_plugin(self, plugin=None, idempotent=False, **kwargs):
"""
Add external plugin to scheduler
See https://distributed.readthedocs.io/en/latest/plugins.html
"""
if isinstance(plugin, type):
plugin = plugin(self, **kwargs)
if idempotent and any(isinstance(p, type(plugin)) for p in self.plugins):
return
self.plugins.append(plugin)
[docs] def remove_plugin(self, plugin):
""" Remove external plugin from scheduler """
self.plugins.remove(plugin)
[docs] def worker_send(self, worker, msg):
""" Send message to worker
This also handles connection failures by adding a callback to remove
the worker on the next cycle.
"""
try:
self.stream_comms[worker].send(msg)
except (CommClosedError, AttributeError):
self.loop.add_callback(self.remove_worker, address=worker)
############################
# Less common interactions #
############################
[docs] async def scatter(
self,
comm=None,
data=None,
workers=None,
client=None,
broadcast=False,
timeout=2,
):
""" Send data out to workers
See also
--------
Scheduler.broadcast:
"""
start = time()
while not self.workers:
await gen.sleep(0.2)
if time() > start + timeout:
raise gen.TimeoutError("No workers found")
if workers is None:
nthreads = {w: ws.nthreads for w, ws in self.workers.items()}
else:
workers = [self.coerce_address(w) for w in workers]
nthreads = {w: self.workers[w].nthreads for w in workers}
assert isinstance(data, dict)
keys, who_has, nbytes = await scatter_to_workers(
nthreads, data, rpc=self.rpc, report=False
)
self.update_data(who_has=who_has, nbytes=nbytes, client=client)
if broadcast:
if broadcast == True: # noqa: E712
n = len(nthreads)
else:
n = broadcast
await self.replicate(keys=keys, workers=workers, n=n)
self.log_event(
[client, "all"], {"action": "scatter", "client": client, "count": len(data)}
)
return keys
[docs] async def gather(self, comm=None, keys=None, serializers=None):
""" Collect data in from workers """
keys = list(keys)
who_has = {}
for key in keys:
ts = self.tasks.get(key)
if ts is not None:
who_has[key] = [ws.address for ws in ts.who_has]
else:
who_has[key] = []
data, missing_keys, missing_workers = await gather_from_workers(
who_has, rpc=self.rpc, close=False, serializers=serializers
)
if not missing_keys:
result = {"status": "OK", "data": data}
else:
missing_states = [
(self.tasks[key].state if key in self.tasks else None)
for key in missing_keys
]
logger.debug(
"Couldn't gather keys %s state: %s workers: %s",
missing_keys,
missing_states,
missing_workers,
)
result = {"status": "error", "keys": missing_keys}
with log_errors():
for worker in missing_workers:
self.remove_worker(address=worker) # this is extreme
for key, workers in missing_keys.items():
if not workers:
continue
ts = self.tasks[key]
logger.exception(
"Workers don't have promised key: %s, %s",
str(workers),
str(key),
)
for worker in workers:
ws = self.workers.get(worker)
if ws is not None and ts in ws.has_what:
ws.has_what.remove(ts)
ts.who_has.remove(ws)
ws.nbytes -= ts.get_nbytes()
self.transitions({key: "released"})
self.log_event("all", {"action": "gather", "count": len(keys)})
return result
def clear_task_state(self):
# XXX what about nested state such as ClientState.wants_what
# (see also fire-and-forget...)
logger.info("Clear task state")
for collection in self._task_state_collections:
collection.clear()
[docs] async def restart(self, client=None, timeout=3):
""" Restart all workers. Reset local state. """
with log_errors():
n_workers = len(self.workers)
logger.info("Send lost future signal to clients")
for cs in self.clients.values():
self.client_releases_keys(
keys=[ts.key for ts in cs.wants_what], client=cs.client_key
)
nannies = {addr: ws.nanny for addr, ws in self.workers.items()}
for addr in list(self.workers):
try:
# Ask the worker to close if it doesn't have a nanny,
# otherwise the nanny will kill it anyway
self.remove_worker(address=addr, close=addr not in nannies)
except Exception as e:
logger.info(
"Exception while restarting. This is normal", exc_info=True
)
self.clear_task_state()
for plugin in self.plugins[:]:
try:
plugin.restart(self)
except Exception as e:
logger.exception(e)
logger.debug("Send kill signal to nannies: %s", nannies)
nannies = [
rpc(nanny_address, connection_args=self.connection_args)
for nanny_address in nannies.values()
if nanny_address is not None
]
try:
resps = All(
[
nanny.restart(
close=True, timeout=timeout * 0.8, executor_wait=False
)
for nanny in nannies
]
)
resps = await gen.with_timeout(timedelta(seconds=timeout), resps)
if not all(resp == "OK" for resp in resps):
logger.error(
"Not all workers responded positively: %s", resps, exc_info=True
)
except gen.TimeoutError:
logger.error(
"Nannies didn't report back restarted within "
"timeout. Continuuing with restart process"
)
finally:
for nanny in nannies:
nanny.close_rpc()
await self.start()
self.log_event([client, "all"], {"action": "restart", "client": client})
start = time()
while time() < start + 10 and len(self.workers) < n_workers:
await gen.sleep(0.01)
self.report({"op": "restart"})
[docs] async def broadcast(
self,
comm=None,
msg=None,
workers=None,
hosts=None,
nanny=False,
serializers=None,
):
""" Broadcast message to workers, return all results """
if workers is None or workers is True:
if hosts is None:
workers = list(self.workers)
else:
workers = []
if hosts is not None:
for host in hosts:
if host in self.host_info:
workers.extend(self.host_info[host]["addresses"])
# TODO replace with worker_list
if nanny:
addresses = [self.workers[w].nanny for w in workers]
else:
addresses = workers
async def send_message(addr):
comm = await connect(
addr, deserialize=self.deserialize, connection_args=self.connection_args
)
comm.name = "Scheduler Broadcast"
resp = await send_recv(comm, close=True, serializers=serializers, **msg)
return resp
results = await All(
[send_message(address) for address in addresses if address is not None]
)
return dict(zip(workers, results))
[docs] async def proxy(self, comm=None, msg=None, worker=None, serializers=None):
""" Proxy a communication through the scheduler to some other worker """
d = await self.broadcast(
comm=comm, msg=msg, workers=[worker], serializers=serializers
)
return d[worker]
[docs] @gen.coroutine
def rebalance(self, comm=None, keys=None, workers=None):
""" Rebalance keys so that each worker stores roughly equal bytes
**Policy**
This orders the workers by what fraction of bytes of the existing keys
they have. It walks down this list from most-to-least. At each worker
it sends the largest results it can find and sends them to the least
occupied worker until either the sender or the recipient are at the
average expected load.
"""
with log_errors():
if keys:
tasks = {self.tasks[k] for k in keys}
missing_data = [ts.key for ts in tasks if not ts.who_has]
if missing_data:
return {"status": "missing-data", "keys": missing_data}
else:
tasks = set(self.tasks.values())
if workers:
workers = {self.workers[w] for w in workers}
workers_by_task = {ts: ts.who_has & workers for ts in tasks}
else:
workers = set(self.workers.values())
workers_by_task = {ts: ts.who_has for ts in tasks}
tasks_by_worker = {ws: set() for ws in workers}
for k, v in workers_by_task.items():
for vv in v:
tasks_by_worker[vv].add(k)
worker_bytes = {
ws: sum(ts.get_nbytes() for ts in v)
for ws, v in tasks_by_worker.items()
}
avg = sum(worker_bytes.values()) / len(worker_bytes)
sorted_workers = list(
map(first, sorted(worker_bytes.items(), key=second, reverse=True))
)
recipients = iter(reversed(sorted_workers))
recipient = next(recipients)
msgs = [] # (sender, recipient, key)
for sender in sorted_workers[: len(workers) // 2]:
sender_keys = {ts: ts.get_nbytes() for ts in tasks_by_worker[sender]}
sender_keys = iter(
sorted(sender_keys.items(), key=second, reverse=True)
)
try:
while worker_bytes[sender] > avg:
while (
worker_bytes[recipient] < avg and worker_bytes[sender] > avg
):
ts, nb = next(sender_keys)
if ts not in tasks_by_worker[recipient]:
tasks_by_worker[recipient].add(ts)
# tasks_by_worker[sender].remove(ts)
msgs.append((sender, recipient, ts))
worker_bytes[sender] -= nb
worker_bytes[recipient] += nb
if worker_bytes[sender] > avg:
recipient = next(recipients)
except StopIteration:
break
to_recipients = defaultdict(lambda: defaultdict(list))
to_senders = defaultdict(list)
for sender, recipient, ts in msgs:
to_recipients[recipient.address][ts.key].append(sender.address)
to_senders[sender.address].append(ts.key)
result = yield {
r: self.rpc(addr=r).gather(who_has=v) for r, v in to_recipients.items()
}
for r, v in to_recipients.items():
self.log_event(r, {"action": "rebalance", "who_has": v})
self.log_event(
"all",
{
"action": "rebalance",
"total-keys": len(tasks),
"senders": valmap(len, to_senders),
"recipients": valmap(len, to_recipients),
"moved_keys": len(msgs),
},
)
if not all(r["status"] == "OK" for r in result.values()):
raise Return(
{
"status": "missing-data",
"keys": sum([r["keys"] for r in result if "keys" in r], []),
}
)
for sender, recipient, ts in msgs:
assert ts.state == "memory"
ts.who_has.add(recipient)
recipient.has_what.add(ts)
recipient.nbytes += ts.get_nbytes()
self.log.append(
("rebalance", ts.key, time(), sender.address, recipient.address)
)
result = yield {
r: self.rpc(addr=r).delete_data(keys=v, report=False)
for r, v in to_senders.items()
}
for sender, recipient, ts in msgs:
ts.who_has.remove(sender)
sender.has_what.remove(ts)
sender.nbytes -= ts.get_nbytes()
raise Return({"status": "OK"})
[docs] @gen.coroutine
def replicate(
self,
comm=None,
keys=None,
n=None,
workers=None,
branching_factor=2,
delete=True,
):
""" Replicate data throughout cluster
This performs a tree copy of the data throughout the network
individually on each piece of data.
Parameters
----------
keys: Iterable
list of keys to replicate
n: int
Number of replications we expect to see within the cluster
branching_factor: int, optional
The number of workers that can copy data in each generation.
The larger the branching factor, the more data we copy in
a single step, but the more a given worker risks being
swamped by data requests.
See also
--------
Scheduler.rebalance
"""
assert branching_factor > 0
workers = {self.workers[w] for w in self.workers_list(workers)}
if n is None:
n = len(workers)
else:
n = min(n, len(workers))
if n == 0:
raise ValueError("Can not use replicate to delete data")
tasks = {self.tasks[k] for k in keys}
missing_data = [ts.key for ts in tasks if not ts.who_has]
if missing_data:
raise Return({"status": "missing-data", "keys": missing_data})
# Delete extraneous data
if delete:
del_worker_tasks = defaultdict(set)
for ts in tasks:
del_candidates = ts.who_has & workers
if len(del_candidates) > n:
for ws in random.sample(del_candidates, len(del_candidates) - n):
del_worker_tasks[ws].add(ts)
yield [
self.rpc(addr=ws.address).delete_data(
keys=[ts.key for ts in tasks], report=False
)
for ws, tasks in del_worker_tasks.items()
]
for ws, tasks in del_worker_tasks.items():
ws.has_what -= tasks
for ts in tasks:
ts.who_has.remove(ws)
ws.nbytes -= ts.get_nbytes()
self.log_event(
ws.address,
{"action": "replicate-remove", "keys": [ts.key for ts in tasks]},
)
# Copy not-yet-filled data
while tasks:
gathers = defaultdict(dict)
for ts in list(tasks):
n_missing = n - len(ts.who_has & workers)
if n_missing <= 0:
# Already replicated enough
tasks.remove(ts)
continue
count = min(n_missing, branching_factor * len(ts.who_has))
assert count > 0
for ws in random.sample(workers - ts.who_has, count):
gathers[ws.address][ts.key] = [wws.address for wws in ts.who_has]
results = yield {
w: self.rpc(addr=w).gather(who_has=who_has)
for w, who_has in gathers.items()
}
for w, v in results.items():
if v["status"] == "OK":
self.add_keys(worker=w, keys=list(gathers[w]))
else:
logger.warning("Communication failed during replication: %s", v)
self.log_event(w, {"action": "replicate-add", "keys": gathers[w]})
self.log_event(
"all",
{
"action": "replicate",
"workers": list(workers),
"key-count": len(keys),
"branching-factor": branching_factor,
},
)
[docs] def workers_to_close(
self,
comm=None,
memory_ratio=None,
n=None,
key=None,
minimum=None,
target=None,
attribute="address",
):
"""
Find workers that we can close with low cost
This returns a list of workers that are good candidates to retire.
These workers are not running anything and are storing
relatively little data relative to their peers. If all workers are
idle then we still maintain enough workers to have enough RAM to store
our data, with a comfortable buffer.
This is for use with systems like ``distributed.deploy.adaptive``.
Parameters
----------
memory_factor: Number
Amount of extra space we want to have for our stored data.
Defaults two 2, or that we want to have twice as much memory as we
currently have data.
n: int
Number of workers to close
minimum: int
Minimum number of workers to keep around
key: Callable(WorkerState)
An optional callable mapping a WorkerState object to a group
affiliation. Groups will be closed together. This is useful when
closing workers must be done collectively, such as by hostname.
target: int
Target number of workers to have after we close
attribute : str
The attribute of the WorkerState object to return, like "address"
or "name". Defaults to "address".
Examples
--------
>>> scheduler.workers_to_close()
['tcp://192.168.0.1:1234', 'tcp://192.168.0.2:1234']
Group workers by hostname prior to closing
>>> scheduler.workers_to_close(key=lambda ws: ws.host)
['tcp://192.168.0.1:1234', 'tcp://192.168.0.1:4567']
Remove two workers
>>> scheduler.workers_to_close(n=2)
Keep enough workers to have twice as much memory as we we need.
>>> scheduler.workers_to_close(memory_ratio=2)
Returns
-------
to_close: list of worker addresses that are OK to close
See Also
--------
Scheduler.retire_workers
"""
if target is not None and n is None:
n = len(self.workers) - target
if n is not None:
if n < 0:
n = 0
target = len(self.workers) - n
if n is None and memory_ratio is None:
memory_ratio = 2
with log_errors():
if not n and all(ws.processing for ws in self.workers.values()):
return []
if key is None:
key = lambda ws: ws.address
if isinstance(key, bytes) and dask.config.get(
"distributed.scheduler.pickle"
):
key = pickle.loads(key)
groups = groupby(key, self.workers.values())
limit_bytes = {
k: sum(ws.memory_limit for ws in v) for k, v in groups.items()
}
group_bytes = {k: sum(ws.nbytes for ws in v) for k, v in groups.items()}
limit = sum(limit_bytes.values())
total = sum(group_bytes.values())
def _key(group):
is_idle = not any(ws.processing for ws in groups[group])
bytes = -group_bytes[group]
return (is_idle, bytes)
idle = sorted(groups, key=_key)
to_close = []
n_remain = len(self.workers)
while idle:
group = idle.pop()
if n is None and any(ws.processing for ws in groups[group]):
break
if minimum and n_remain - len(groups[group]) < minimum:
break
limit -= limit_bytes[group]
if (n is not None and n_remain - len(groups[group]) >= target) or (
memory_ratio is not None and limit >= memory_ratio * total
):
to_close.append(group)
n_remain -= len(groups[group])
else:
break
result = [getattr(ws, attribute) for g in to_close for ws in groups[g]]
if result:
logger.info("Suggest closing workers: %s", result)
return result
[docs] async def retire_workers(
self,
comm=None,
workers=None,
remove=True,
close_workers=False,
names=None,
**kwargs
):
""" Gracefully retire workers from cluster
Parameters
----------
workers: list (optional)
List of worker addresses to retire.
If not provided we call ``workers_to_close`` which finds a good set
workers_names: list (optional)
List of worker names to retire.
remove: bool (defaults to True)
Whether or not to remove the worker metadata immediately or else
wait for the worker to contact us
close_workers: bool (defaults to False)
Whether or not to actually close the worker explicitly from here.
Otherwise we expect some external job scheduler to finish off the
worker.
**kwargs: dict
Extra options to pass to workers_to_close to determine which
workers we should drop
Returns
-------
Dictionary mapping worker ID/address to dictionary of information about
that worker for each retired worker.
See Also
--------
Scheduler.workers_to_close
"""
with log_errors():
if names is not None:
if names:
logger.info("Retire worker names %s", names)
names = set(map(str, names))
workers = [
ws.address for ws in self.workers.values() if str(ws.name) in names
]
if workers is None:
while True:
try:
workers = self.workers_to_close(**kwargs)
if workers:
workers = await self.retire_workers(
workers=workers,
remove=remove,
close_workers=close_workers,
)
return workers
except KeyError: # keys left during replicate
pass
workers = {self.workers[w] for w in workers if w in self.workers}
if not workers:
return []
logger.info("Retire workers %s", workers)
# Keys orphaned by retiring those workers
keys = set.union(*[w.has_what for w in workers])
keys = {ts.key for ts in keys if ts.who_has.issubset(workers)}
other_workers = set(self.workers.values()) - workers
if keys:
if other_workers:
logger.info("Moving %d keys to other workers", len(keys))
await self.replicate(
keys=keys,
workers=[ws.address for ws in other_workers],
n=1,
delete=False,
)
else:
return []
worker_keys = {ws.address: ws.identity() for ws in workers}
if close_workers and worker_keys:
await asyncio.gather(
*[self.close_worker(worker=w, safe=True) for w in worker_keys]
)
if remove:
for w in worker_keys:
self.remove_worker(address=w, safe=True)
self.log_event(
"all",
{
"action": "retire-workers",
"workers": worker_keys,
"moved-keys": len(keys),
},
)
self.log_event(list(worker_keys), {"action": "retired"})
return worker_keys
[docs] def add_keys(self, comm=None, worker=None, keys=()):
"""
Learn that a worker has certain keys
This should not be used in practice and is mostly here for legacy
reasons. However, it is sent by workers from time to time.
"""
if worker not in self.workers:
return "not found"
ws = self.workers[worker]
for key in keys:
ts = self.tasks.get(key)
if ts is not None and ts.state == "memory":
if ts not in ws.has_what:
ws.nbytes += ts.get_nbytes()
ws.has_what.add(ts)
ts.who_has.add(ws)
else:
self.worker_send(
worker, {"op": "delete-data", "keys": [key], "report": False}
)
return "OK"
[docs] def update_data(
self, comm=None, who_has=None, nbytes=None, client=None, serializers=None
):
"""
Learn that new data has entered the network from an external source
See Also
--------
Scheduler.mark_key_in_memory
"""
with log_errors():
who_has = {
k: [self.coerce_address(vv) for vv in v] for k, v in who_has.items()
}
logger.debug("Update data %s", who_has)
for key, workers in who_has.items():
ts = self.tasks.get(key)
if ts is None:
ts = self.tasks[key] = TaskState(key, None)
ts.state = "memory"
if key in nbytes:
ts.set_nbytes(nbytes[key])
for w in workers:
ws = self.workers[w]
if ts not in ws.has_what:
ws.nbytes += ts.get_nbytes()
ws.has_what.add(ts)
ts.who_has.add(ws)
self.report(
{"op": "key-in-memory", "key": key, "workers": list(workers)}
)
if client:
self.client_desires_keys(keys=list(who_has), client=client)
def report_on_key(self, key=None, ts=None, client=None):
assert (key is None) + (ts is None) == 1, (key, ts)
if ts is None:
try:
ts = self.tasks[key]
except KeyError:
self.report({"op": "cancelled-key", "key": key}, client=client)
return
else:
key = ts.key
if ts.state == "forgotten":
self.report({"op": "cancelled-key", "key": key}, ts=ts, client=client)
elif ts.state == "memory":
self.report({"op": "key-in-memory", "key": key}, ts=ts, client=client)
elif ts.state == "erred":
failing_ts = ts.exception_blame
self.report(
{
"op": "task-erred",
"key": key,
"exception": failing_ts.exception,
"traceback": failing_ts.traceback,
},
ts=ts,
client=client,
)
[docs] async def feed(
self, comm, function=None, setup=None, teardown=None, interval="1s", **kwargs
):
"""
Provides a data Comm to external requester
Caution: this runs arbitrary Python code on the scheduler. This should
eventually be phased out. It is mostly used by diagnostics.
"""
if not dask.config.get("distributed.scheduler.pickle"):
logger.warn(
"Tried to call 'feed' route with custom fucntions, but "
"pickle is disallowed. Set the 'distributed.scheduler.pickle'"
"config value to True to use the 'feed' route (this is mostly "
"commonly used with progress bars)"
)
return
import pickle
interval = parse_timedelta(interval)
with log_errors():
if function:
function = pickle.loads(function)
if setup:
setup = pickle.loads(setup)
if teardown:
teardown = pickle.loads(teardown)
state = setup(self) if setup else None
if hasattr(state, "__await__"):
state = await state
try:
while self.status == "running":
if state is None:
response = function(self)
else:
response = function(self, state)
await comm.write(response)
await gen.sleep(interval)
except (EnvironmentError, CommClosedError):
pass
finally:
if teardown:
teardown(self, state)
def subscribe_worker_status(self, comm=None):
WorkerStatusPlugin(self, comm)
ident = self.identity()
for v in ident["workers"].values():
del v["metrics"]
del v["last_seen"]
return ident
def get_processing(self, comm=None, workers=None):
if workers is not None:
workers = set(map(self.coerce_address, workers))
return {w: [ts.key for ts in self.workers[w].processing] for w in workers}
else:
return {
w: [ts.key for ts in ws.processing] for w, ws in self.workers.items()
}
def get_who_has(self, comm=None, keys=None):
if keys is not None:
return {
k: [ws.address for ws in self.tasks[k].who_has]
if k in self.tasks
else []
for k in keys
}
else:
return {
key: [ws.address for ws in ts.who_has] for key, ts in self.tasks.items()
}
def get_has_what(self, comm=None, workers=None):
if workers is not None:
workers = map(self.coerce_address, workers)
return {
w: [ts.key for ts in self.workers[w].has_what]
if w in self.workers
else []
for w in workers
}
else:
return {w: [ts.key for ts in ws.has_what] for w, ws in self.workers.items()}
def get_ncores(self, comm=None, workers=None):
if workers is not None:
workers = map(self.coerce_address, workers)
return {w: self.workers[w].nthreads for w in workers if w in self.workers}
else:
return {w: ws.nthreads for w, ws in self.workers.items()}
@gen.coroutine
def get_call_stack(self, comm=None, keys=None):
if keys is not None:
stack = list(keys)
processing = set()
while stack:
key = stack.pop()
ts = self.tasks[key]
if ts.state == "waiting":
stack.extend(dts.key for dts in ts.dependencies)
elif ts.state == "processing":
processing.add(ts)
workers = defaultdict(list)
for ts in processing:
if ts.processing_on:
workers[ts.processing_on.address].append(ts.key)
else:
workers = {w: None for w in self.workers}
if not workers:
raise gen.Return({})
else:
response = yield {
w: self.rpc(w).call_stack(keys=v) for w, v in workers.items()
}
response = {k: v for k, v in response.items() if v}
raise gen.Return(response)
def get_nbytes(self, comm=None, keys=None, summary=True):
with log_errors():
if keys is not None:
result = {k: self.tasks[k].nbytes for k in keys}
else:
result = {
k: ts.nbytes
for k, ts in self.tasks.items()
if ts.nbytes is not None
}
if summary:
out = defaultdict(lambda: 0)
for k, v in result.items():
out[key_split(k)] += v
result = dict(out)
return result
[docs] def get_comm_cost(self, ts, ws):
"""
Get the estimated communication cost (in s.) to compute the task
on the given worker.
"""
return sum(dts.nbytes for dts in ts.dependencies - ws.has_what) / self.bandwidth
[docs] def get_task_duration(self, ts, default=0.5):
"""
Get the estimated computation cost of the given task
(not including any communication cost).
"""
prefix = ts.prefix
try:
return self.task_duration[prefix]
except KeyError:
self.unknown_durations[prefix].add(ts)
return default
[docs] def run_function(self, stream, function, args=(), kwargs={}, wait=True):
""" Run a function within this process
See Also
--------
Client.run_on_scheduler:
"""
from .worker import run
self.log_event("all", {"action": "run-function", "function": function})
return run(self, stream, function=function, args=args, kwargs=kwargs, wait=wait)
def set_metadata(self, stream=None, keys=None, value=None):
try:
metadata = self.task_metadata
for key in keys[:-1]:
if key not in metadata or not isinstance(metadata[key], (dict, list)):
metadata[key] = dict()
metadata = metadata[key]
metadata[keys[-1]] = value
except Exception as e:
import pdb
pdb.set_trace()
def get_metadata(self, stream=None, keys=None, default=no_default):
metadata = self.task_metadata
for key in keys[:-1]:
metadata = metadata[key]
try:
return metadata[keys[-1]]
except KeyError:
if default != no_default:
return default
else:
raise
def get_task_status(self, stream=None, keys=None):
return {
key: (self.tasks[key].state if key in self.tasks else None) for key in keys
}
def get_task_stream(self, comm=None, start=None, stop=None, count=None):
from distributed.diagnostics.task_stream import TaskStreamPlugin
self.add_plugin(TaskStreamPlugin, idempotent=True)
ts = [p for p in self.plugins if isinstance(p, TaskStreamPlugin)][0]
return ts.collect(start=start, stop=stop, count=count)
[docs] async def register_worker_plugin(self, comm, plugin, name=None):
""" Registers a setup function, and call it on every worker """
self.worker_plugins.append(plugin)
responses = await self.broadcast(
msg=dict(op="plugin-add", plugin=plugin, name=name)
)
return responses
#####################
# State Transitions #
#####################
def _remove_from_processing(self, ts, send_worker_msg=None):
"""
Remove *ts* from the set of processing tasks.
"""
ws = ts.processing_on
ts.processing_on = None
w = ws.address
if w in self.workers: # may have been removed
duration = ws.processing.pop(ts)
if not ws.processing:
self.total_occupancy -= ws.occupancy
ws.occupancy = 0
else:
self.total_occupancy -= duration
ws.occupancy -= duration
self.check_idle_saturated(ws)
self.release_resources(ts, ws)
if send_worker_msg:
self.worker_send(w, send_worker_msg)
def _add_to_memory(
self, ts, ws, recommendations, type=None, typename=None, **kwargs
):
"""
Add *ts* to the set of in-memory tasks.
"""
if self.validate:
assert ts not in ws.has_what
ts.who_has.add(ws)
ws.has_what.add(ts)
ws.nbytes += ts.get_nbytes()
deps = ts.dependents
if len(deps) > 1:
deps = sorted(deps, key=operator.attrgetter("priority"), reverse=True)
for dts in deps:
s = dts.waiting_on
if ts in s:
s.discard(ts)
if not s: # new task ready to run
recommendations[dts.key] = "processing"
for dts in ts.dependencies:
s = dts.waiters
s.discard(ts)
if not s and not dts.who_wants:
recommendations[dts.key] = "released"
if not ts.waiters and not ts.who_wants:
recommendations[ts.key] = "released"
else:
msg = {"op": "key-in-memory", "key": ts.key}
if type is not None:
msg["type"] = type
self.report(msg)
ts.state = "memory"
ts.type = typename
cs = self.clients["fire-and-forget"]
if ts in cs.wants_what:
self.client_releases_keys(client="fire-and-forget", keys=[ts.key])
def transition_released_waiting(self, key):
try:
ts = self.tasks[key]
if self.validate:
assert ts.run_spec
assert not ts.waiting_on
assert not ts.who_has
assert not ts.processing_on
assert not any(dts.state == "forgotten" for dts in ts.dependencies)
if ts.has_lost_dependencies:
return {key: "forgotten"}
ts.state = "waiting"
recommendations = OrderedDict()
for dts in ts.dependencies:
if dts.exception_blame:
ts.exception_blame = dts.exception_blame
recommendations[key] = "erred"
return recommendations
for dts in ts.dependencies:
dep = dts.key
if not dts.who_has:
ts.waiting_on.add(dts)
if dts.state == "released":
recommendations[dep] = "waiting"
else:
dts.waiters.add(ts)
ts.waiters = {dts for dts in ts.dependents if dts.state == "waiting"}
if not ts.waiting_on:
if self.workers:
recommendations[key] = "processing"
else:
self.unrunnable.add(ts)
ts.state = "no-worker"
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_no_worker_waiting(self, key):
try:
ts = self.tasks[key]
if self.validate:
assert ts in self.unrunnable
assert not ts.waiting_on
assert not ts.who_has
assert not ts.processing_on
self.unrunnable.remove(ts)
if ts.has_lost_dependencies:
return {key: "forgotten"}
recommendations = OrderedDict()
for dts in ts.dependencies:
dep = dts.key
if not dts.who_has:
ts.waiting_on.add(dts)
if dts.state == "released":
recommendations[dep] = "waiting"
else:
dts.waiters.add(ts)
ts.state = "waiting"
if not ts.waiting_on:
if self.workers:
recommendations[key] = "processing"
else:
self.unrunnable.add(ts)
ts.state = "no-worker"
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
[docs] def decide_worker(self, ts):
"""
Decide on a worker for task *ts*. Return a WorkerState.
"""
valid_workers = self.valid_workers(ts)
if not valid_workers and not ts.loose_restrictions and self.workers:
self.unrunnable.add(ts)
ts.state = "no-worker"
return None
if ts.dependencies or valid_workers is not True:
worker = decide_worker(
ts,
self.workers.values(),
valid_workers,
partial(self.worker_objective, ts),
)
elif self.idle:
if len(self.idle) < 20: # smart but linear in small case
worker = min(self.idle, key=operator.attrgetter("occupancy"))
else: # dumb but fast in large case
worker = self.idle[self.n_tasks % len(self.idle)]
else:
if len(self.workers) < 20: # smart but linear in small case
worker = min(
self.workers.values(), key=operator.attrgetter("occupancy")
)
else: # dumb but fast in large case
worker = self.workers.values()[self.n_tasks % len(self.workers)]
if self.validate:
assert worker is None or isinstance(worker, WorkerState), (
type(worker),
worker,
)
assert worker.address in self.workers
return worker
def transition_waiting_processing(self, key):
try:
ts = self.tasks[key]
if self.validate:
assert not ts.waiting_on
assert not ts.who_has
assert not ts.exception_blame
assert not ts.processing_on
assert not ts.has_lost_dependencies
assert ts not in self.unrunnable
assert all(dts.who_has for dts in ts.dependencies)
ws = self.decide_worker(ts)
if ws is None:
return {}
worker = ws.address
duration = self.get_task_duration(ts)
comm = self.get_comm_cost(ts, ws)
ws.processing[ts] = duration + comm
ts.processing_on = ws
ws.occupancy += duration + comm
self.total_occupancy += duration + comm
ts.state = "processing"
self.consume_resources(ts, ws)
self.check_idle_saturated(ws)
self.n_tasks += 1
if ts.actor:
ws.actors.add(ts)
# logger.debug("Send job to worker: %s, %s", worker, key)
self.send_task_to_worker(worker, key)
return {}
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_waiting_memory(self, key, nbytes=None, worker=None, **kwargs):
try:
ws = self.workers[worker]
ts = self.tasks[key]
if self.validate:
assert not ts.processing_on
assert ts.waiting_on
assert ts.state == "waiting"
ts.waiting_on.clear()
if nbytes is not None:
ts.set_nbytes(nbytes)
self.check_idle_saturated(ws)
recommendations = OrderedDict()
self._add_to_memory(ts, ws, recommendations, **kwargs)
if self.validate:
assert not ts.processing_on
assert not ts.waiting_on
assert ts.who_has
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_processing_memory(
self,
key,
nbytes=None,
type=None,
typename=None,
worker=None,
startstops=None,
**kwargs
):
try:
ts = self.tasks[key]
assert worker
assert isinstance(worker, str)
if self.validate:
assert ts.processing_on
ws = ts.processing_on
assert ts in ws.processing
assert not ts.waiting_on
assert not ts.who_has, (ts, ts.who_has)
assert not ts.exception_blame
assert ts.state == "processing"
ws = self.workers.get(worker)
if ws is None:
return {key: "released"}
if ws is not ts.processing_on: # someone else has this task
logger.info(
"Unexpected worker completed task, likely due to"
" work stealing. Expected: %s, Got: %s, Key: %s",
ts.processing_on,
ws,
key,
)
return {}
if startstops:
L = [(b, c) for a, b, c in startstops if a == "compute"]
if L:
compute_start, compute_stop = L[0]
else: # This is very rare
compute_start = compute_stop = None
else:
compute_start = compute_stop = None
#############################
# Update Timing Information #
#############################
if compute_start and ws.processing.get(ts, True):
# Update average task duration for worker
prefix = ts.prefix
old_duration = self.task_duration.get(prefix, 0)
new_duration = compute_stop - compute_start
if not old_duration:
avg_duration = new_duration
else:
avg_duration = 0.5 * old_duration + 0.5 * new_duration
self.task_duration[prefix] = avg_duration
for tts in self.unknown_durations.pop(prefix, ()):
if tts.processing_on:
wws = tts.processing_on
old = wws.processing[tts]
comm = self.get_comm_cost(tts, wws)
wws.processing[tts] = avg_duration + comm
wws.occupancy += avg_duration + comm - old
self.total_occupancy += avg_duration + comm - old
############################
# Update State Information #
############################
if nbytes is not None:
ts.set_nbytes(nbytes)
recommendations = OrderedDict()
self._remove_from_processing(ts)
self._add_to_memory(ts, ws, recommendations, type=type, typename=typename)
if self.validate:
assert not ts.processing_on
assert not ts.waiting_on
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_memory_released(self, key, safe=False):
try:
ts = self.tasks[key]
if self.validate:
assert not ts.waiting_on
assert not ts.processing_on
if safe:
assert not ts.waiters
if ts.actor:
for ws in ts.who_has:
ws.actors.discard(ts)
if ts.who_wants:
ts.exception_blame = ts
ts.exception = "Worker holding Actor was lost"
return {ts.key: "erred"} # don't try to recreate
recommendations = OrderedDict()
for dts in ts.waiters:
if dts.state in ("no-worker", "processing"):
recommendations[dts.key] = "waiting"
elif dts.state == "waiting":
dts.waiting_on.add(ts)
# XXX factor this out?
for ws in ts.who_has:
ws.has_what.remove(ts)
ws.nbytes -= ts.get_nbytes()
self.worker_send(
ws.address, {"op": "delete-data", "keys": [key], "report": False}
)
ts.who_has.clear()
ts.state = "released"
self.report({"op": "lost-data", "key": key})
if not ts.run_spec: # pure data
recommendations[key] = "forgotten"
elif ts.has_lost_dependencies:
recommendations[key] = "forgotten"
elif ts.who_wants or ts.waiters:
recommendations[key] = "waiting"
if self.validate:
assert not ts.waiting_on
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_released_erred(self, key):
try:
ts = self.tasks[key]
if self.validate:
with log_errors(pdb=LOG_PDB):
assert ts.exception_blame
assert not ts.who_has
assert not ts.waiting_on
assert not ts.waiters
recommendations = {}
failing_ts = ts.exception_blame
for dts in ts.dependents:
dts.exception_blame = failing_ts
if not dts.who_has:
recommendations[dts.key] = "erred"
self.report(
{
"op": "task-erred",
"key": key,
"exception": failing_ts.exception,
"traceback": failing_ts.traceback,
}
)
ts.state = "erred"
# TODO: waiting data?
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_erred_released(self, key):
try:
ts = self.tasks[key]
if self.validate:
with log_errors(pdb=LOG_PDB):
assert all(dts.state != "erred" for dts in ts.dependencies)
assert ts.exception_blame
assert not ts.who_has
assert not ts.waiting_on
assert not ts.waiters
recommendations = OrderedDict()
ts.exception = None
ts.exception_blame = None
ts.traceback = None
for dep in ts.dependents:
if dep.state == "erred":
recommendations[dep.key] = "waiting"
self.report({"op": "task-retried", "key": key})
ts.state = "released"
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_waiting_released(self, key):
try:
ts = self.tasks[key]
if self.validate:
assert not ts.who_has
assert not ts.processing_on
recommendations = {}
for dts in ts.dependencies:
s = dts.waiters
if ts in s:
s.discard(ts)
if not s and not dts.who_wants:
recommendations[dts.key] = "released"
ts.waiting_on.clear()
ts.state = "released"
if ts.has_lost_dependencies:
recommendations[key] = "forgotten"
elif not ts.exception_blame and (ts.who_wants or ts.waiters):
recommendations[key] = "waiting"
else:
ts.waiters.clear()
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_processing_released(self, key):
try:
ts = self.tasks[key]
if self.validate:
assert ts.processing_on
assert not ts.who_has
assert not ts.waiting_on
assert self.tasks[key].state == "processing"
self._remove_from_processing(
ts, send_worker_msg={"op": "release-task", "key": key}
)
ts.state = "released"
recommendations = OrderedDict()
if ts.has_lost_dependencies:
recommendations[key] = "forgotten"
elif ts.waiters or ts.who_wants:
recommendations[key] = "waiting"
if recommendations.get(key) != "waiting":
for dts in ts.dependencies:
if dts.state != "released":
s = dts.waiters
s.discard(ts)
if not s and not dts.who_wants:
recommendations[dts.key] = "released"
ts.waiters.clear()
if self.validate:
assert not ts.processing_on
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_processing_erred(
self, key, cause=None, exception=None, traceback=None, **kwargs
):
try:
ts = self.tasks[key]
if self.validate:
assert cause or ts.exception_blame
assert ts.processing_on
assert not ts.who_has
assert not ts.waiting_on
if ts.actor:
ws = ts.processing_on
ws.actors.remove(ts)
self._remove_from_processing(ts)
if exception is not None:
ts.exception = exception
if traceback is not None:
ts.traceback = traceback
if cause is not None:
failing_ts = self.tasks[cause]
ts.exception_blame = failing_ts
else:
failing_ts = ts.exception_blame
recommendations = {}
for dts in ts.dependents:
dts.exception_blame = failing_ts
recommendations[dts.key] = "erred"
for dts in ts.dependencies:
s = dts.waiters
s.discard(ts)
if not s and not dts.who_wants:
recommendations[dts.key] = "released"
ts.waiters.clear() # do anything with this?
ts.state = "erred"
self.report(
{
"op": "task-erred",
"key": key,
"exception": failing_ts.exception,
"traceback": failing_ts.traceback,
}
)
cs = self.clients["fire-and-forget"]
if ts in cs.wants_what:
self.client_releases_keys(client="fire-and-forget", keys=[key])
if self.validate:
assert not ts.processing_on
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_no_worker_released(self, key):
try:
ts = self.tasks[key]
if self.validate:
assert self.tasks[key].state == "no-worker"
assert not ts.who_has
assert not ts.waiting_on
self.unrunnable.remove(ts)
ts.state = "released"
for dts in ts.dependencies:
dts.waiters.discard(ts)
ts.waiters.clear()
return {}
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def remove_key(self, key):
ts = self.tasks.pop(key)
assert ts.state == "forgotten"
self.unrunnable.discard(ts)
for cs in ts.who_wants:
cs.wants_what.remove(ts)
ts.who_wants.clear()
ts.processing_on = None
ts.exception_blame = ts.exception = ts.traceback = None
if key in self.task_metadata:
del self.task_metadata[key]
def _propagate_forgotten(self, ts, recommendations):
ts.state = "forgotten"
key = ts.key
for dts in ts.dependents:
dts.has_lost_dependencies = True
dts.dependencies.remove(ts)
dts.waiting_on.discard(ts)
if dts.state not in ("memory", "erred"):
# Cannot compute task anymore
recommendations[dts.key] = "forgotten"
ts.dependents.clear()
ts.waiters.clear()
for dts in ts.dependencies:
dts.dependents.remove(ts)
s = dts.waiters
s.discard(ts)
if not dts.dependents and not dts.who_wants:
# Task not needed anymore
assert dts is not ts
recommendations[dts.key] = "forgotten"
ts.dependencies.clear()
ts.waiting_on.clear()
for ws in ts.who_has:
ws.has_what.remove(ts)
ws.nbytes -= ts.get_nbytes()
w = ws.address
if w in self.workers: # in case worker has died
self.worker_send(
w, {"op": "delete-data", "keys": [key], "report": False}
)
ts.who_has.clear()
def transition_memory_forgotten(self, key):
try:
ts = self.tasks[key]
if self.validate:
assert ts.state == "memory"
assert not ts.processing_on
assert not ts.waiting_on
if not ts.run_spec:
# It's ok to forget a pure data task
pass
elif ts.has_lost_dependencies:
# It's ok to forget a task with forgotten dependencies
pass
elif not ts.who_wants and not ts.waiters and not ts.dependents:
# It's ok to forget a task that nobody needs
pass
else:
assert 0, (ts,)
recommendations = {}
if ts.actor:
for ws in ts.who_has:
ws.actors.discard(ts)
self._propagate_forgotten(ts, recommendations)
self.report_on_key(ts=ts)
self.remove_key(key)
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
def transition_released_forgotten(self, key):
try:
ts = self.tasks[key]
if self.validate:
assert ts.state in ("released", "erred")
assert not ts.who_has
assert not ts.processing_on
assert not ts.waiting_on, (ts, ts.waiting_on)
if not ts.run_spec:
# It's ok to forget a pure data task
pass
elif ts.has_lost_dependencies:
# It's ok to forget a task with forgotten dependencies
pass
elif not ts.who_wants and not ts.waiters and not ts.dependents:
# It's ok to forget a task that nobody needs
pass
else:
assert 0, (ts,)
recommendations = {}
self._propagate_forgotten(ts, recommendations)
self.report_on_key(ts=ts)
self.remove_key(key)
return recommendations
except Exception as e:
logger.exception(e)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
[docs] def transition(self, key, finish, *args, **kwargs):
""" Transition a key from its current state to the finish state
Examples
--------
>>> self.transition('x', 'waiting')
{'x': 'processing'}
Returns
-------
Dictionary of recommendations for future transitions
See Also
--------
Scheduler.transitions: transitive version of this function
"""
try:
try:
ts = self.tasks[key]
except KeyError:
return {}
start = ts.state
if start == finish:
return {}
if self.plugins:
dependents = set(ts.dependents)
dependencies = set(ts.dependencies)
if (start, finish) in self._transitions:
func = self._transitions[start, finish]
recommendations = func(key, *args, **kwargs)
elif "released" not in (start, finish):
func = self._transitions["released", finish]
assert not args and not kwargs
a = self.transition(key, "released")
if key in a:
func = self._transitions["released", a[key]]
b = func(key)
a = a.copy()
a.update(b)
recommendations = a
start = "released"
else:
raise RuntimeError(
"Impossible transition from %r to %r" % (start, finish)
)
finish2 = ts.state
self.transition_log.append((key, start, finish2, recommendations, time()))
if self.validate:
logger.debug(
"Transitioned %r %s->%s (actual: %s). Consequence: %s",
key,
start,
finish2,
ts.state,
dict(recommendations),
)
if self.plugins:
# Temporarily put back forgotten key for plugin to retrieve it
if ts.state == "forgotten":
try:
ts.dependents = dependents
ts.dependencies = dependencies
except KeyError:
pass
self.tasks[ts.key] = ts
for plugin in list(self.plugins):
try:
plugin.transition(key, start, finish2, *args, **kwargs)
except Exception:
logger.info("Plugin failed with exception", exc_info=True)
if ts.state == "forgotten":
del self.tasks[ts.key]
return recommendations
except Exception as e:
logger.exception("Error transitioning %r from %r to %r", key, start, finish)
if LOG_PDB:
import pdb
pdb.set_trace()
raise
[docs] def transitions(self, recommendations):
""" Process transitions until none are left
This includes feedback from previous transitions and continues until we
reach a steady state
"""
keys = set()
recommendations = recommendations.copy()
while recommendations:
key, finish = recommendations.popitem()
keys.add(key)
new = self.transition(key, finish)
recommendations.update(new)
if self.validate:
for key in keys:
self.validate_key(key)
[docs] def story(self, *keys):
""" Get all transitions that touch one of the input keys """
keys = set(keys)
return [
t for t in self.transition_log if t[0] in keys or keys.intersection(t[3])
]
transition_story = story
[docs] def reschedule(self, key=None, worker=None):
""" Reschedule a task
Things may have shifted and this task may now be better suited to run
elsewhere
"""
try:
ts = self.tasks[key]
except KeyError:
logger.warning(
"Attempting to reschedule task {}, which was not "
"found on the scheduler. Aborting reschedule.".format(key)
)
return
if ts.state != "processing":
return
if worker and ts.processing_on.address != worker:
return
self.transitions({key: "released"})
##############################
# Assigning Tasks to Workers #
##############################
[docs] def check_idle_saturated(self, ws, occ=None):
""" Update the status of the idle and saturated state
The scheduler keeps track of workers that are ..
- Saturated: have enough work to stay busy
- Idle: do not have enough work to stay busy
They are considered saturated if they both have enough tasks to occupy
all of their threads, and if the expected runtime of those tasks is
large enough.
This is useful for load balancing and adaptivity.
"""
if self.total_nthreads == 0 or ws.status == "closed":
return
if occ is None:
occ = ws.occupancy
nc = ws.nthreads
p = len(ws.processing)
avg = self.total_occupancy / self.total_nthreads
if p < nc or occ / nc < avg / 2:
self.idle.add(ws)
self.saturated.discard(ws)
else:
self.idle.discard(ws)
pending = occ * (p - nc) / p / nc
if p > nc and pending > 0.4 and pending > 1.9 * avg:
self.saturated.add(ws)
else:
self.saturated.discard(ws)
[docs] def valid_workers(self, ts):
""" Return set of currently valid workers for key
If all workers are valid then this returns ``True``.
This checks tracks the following state:
* worker_restrictions
* host_restrictions
* resource_restrictions
"""
s = True
if ts.worker_restrictions:
s = {w for w in ts.worker_restrictions if w in self.workers}
if ts.host_restrictions:
# Resolve the alias here rather than early, for the worker
# may not be connected when host_restrictions is populated
hr = [self.coerce_hostname(h) for h in ts.host_restrictions]
# XXX need HostState?
ss = [self.host_info[h]["addresses"] for h in hr if h in self.host_info]
ss = set.union(*ss) if ss else set()
if s is True:
s = ss
else:
s |= ss
if ts.resource_restrictions:
w = {
resource: {
w
for w, supplied in self.resources[resource].items()
if supplied >= required
}
for resource, required in ts.resource_restrictions.items()
}
ww = set.intersection(*w.values())
if s is True:
s = ww
else:
s &= ww
if s is True:
return s
else:
return {self.workers[w] for w in s}
def consume_resources(self, ts, ws):
if ts.resource_restrictions:
for r, required in ts.resource_restrictions.items():
ws.used_resources[r] += required
def release_resources(self, ts, ws):
if ts.resource_restrictions:
for r, required in ts.resource_restrictions.items():
ws.used_resources[r] -= required
#####################
# Utility functions #
#####################
def add_resources(self, stream=None, worker=None, resources=None):
ws = self.workers[worker]
if resources:
ws.resources.update(resources)
ws.used_resources = {}
for resource, quantity in ws.resources.items():
ws.used_resources[resource] = 0
self.resources[resource][worker] = quantity
return "OK"
def remove_resources(self, worker):
ws = self.workers[worker]
for resource, quantity in ws.resources.items():
del self.resources[resource][worker]
[docs] def coerce_address(self, addr, resolve=True):
"""
Coerce possible input addresses to canonical form.
*resolve* can be disabled for testing with fake hostnames.
Handles strings, tuples, or aliases.
"""
# XXX how many address-parsing routines do we have?
if addr in self.aliases:
addr = self.aliases[addr]
if isinstance(addr, tuple):
addr = unparse_host_port(*addr)
if not isinstance(addr, str):
raise TypeError("addresses should be strings or tuples, got %r" % (addr,))
if resolve:
addr = resolve_address(addr)
else:
addr = normalize_address(addr)
return addr
[docs] def coerce_hostname(self, host):
"""
Coerce the hostname of a worker.
"""
if host in self.aliases:
return self.workers[self.aliases[host]].host
else:
return host
[docs] def workers_list(self, workers):
"""
List of qualifying workers
Takes a list of worker addresses or hostnames.
Returns a list of all worker addresses that match
"""
if workers is None:
return list(self.workers)
out = set()
for w in workers:
if ":" in w:
out.add(w)
else:
out.update({ww for ww in self.workers if w in ww}) # TODO: quadratic
return list(out)
[docs] def start_ipython(self, comm=None):
"""Start an IPython kernel
Returns Jupyter connection info dictionary.
"""
from ._ipython_utils import start_ipython
if self._ipython_kernel is None:
self._ipython_kernel = start_ipython(
ip=self.ip, ns={"scheduler": self}, log=logger
)
return self._ipython_kernel.get_connection_info()
[docs] def worker_objective(self, ts, ws):
"""
Objective function to determine which worker should get the task
Minimize expected start time. If a tie then break with data storage.
"""
comm_bytes = sum(
[dts.get_nbytes() for dts in ts.dependencies if ws not in dts.who_has]
)
stack_time = ws.occupancy / ws.nthreads
start_time = comm_bytes / self.bandwidth + stack_time
if ts.actor:
return (len(ws.actors), start_time, ws.nbytes)
else:
return (start_time, ws.nbytes)
@gen.coroutine
def get_profile(
self,
comm=None,
workers=None,
merge_workers=True,
start=None,
stop=None,
key=None,
):
if workers is None:
workers = self.workers
else:
workers = set(self.workers) & set(workers)
result = yield {
w: self.rpc(w).profile(start=start, stop=stop, key=key) for w in workers
}
if merge_workers:
result = profile.merge(*result.values())
raise gen.Return(result)
@gen.coroutine
def get_profile_metadata(
self,
comm=None,
workers=None,
merge_workers=True,
start=None,
stop=None,
profile_cycle_interval=None,
):
dt = profile_cycle_interval or dask.config.get(
"distributed.worker.profile.cycle"
)
dt = parse_timedelta(dt, default="ms")
if workers is None:
workers = self.workers
else:
workers = set(self.workers) & set(workers)
result = yield {
w: self.rpc(w).profile_metadata(start=start, stop=stop) for w in workers
}
counts = [v["counts"] for v in result.values()]
counts = itertools.groupby(merge_sorted(*counts), lambda t: t[0] // dt * dt)
counts = [(time, sum(pluck(1, group))) for time, group in counts]
keys = set()
for v in result.values():
for t, d in v["keys"]:
for k in d:
keys.add(k)
keys = {k: [] for k in keys}
groups1 = [v["keys"] for v in result.values()]
groups2 = list(merge_sorted(*groups1, key=first))
last = 0
for t, d in groups2:
tt = t // dt * dt
if tt > last:
last = tt
for k, v in keys.items():
v.append([tt, 0])
for k, v in d.items():
keys[k][-1][1] += v
raise gen.Return({"counts": counts, "keys": keys})
async def get_worker_logs(self, comm=None, n=None, workers=None, nanny=False):
results = await self.broadcast(
msg={"op": "get_logs", "n": n}, workers=workers, nanny=nanny
)
return results
###########
# Cleanup #
###########
[docs] def reevaluate_occupancy(self, worker_index=0):
""" Periodically reassess task duration time
The expected duration of a task can change over time. Unfortunately we
don't have a good constant-time way to propagate the effects of these
changes out to the summaries that they affect, like the total expected
runtime of each of the workers, or what tasks are stealable.
In this coroutine we walk through all of the workers and re-align their
estimates with the current state of tasks. We do this periodically
rather than at every transition, and we only do it if the scheduler
process isn't under load (using psutil.Process.cpu_percent()). This
lets us avoid this fringe optimization when we have better things to
think about.
"""
DELAY = 0.1
try:
if self.status == "closed":
return
last = time()
next_time = timedelta(seconds=DELAY)
if self.proc.cpu_percent() < 50:
workers = list(self.workers.values())
for i in range(len(workers)):
ws = workers[worker_index % len(workers)]
worker_index += 1
try:
if ws is None or not ws.processing:
continue
self._reevaluate_occupancy_worker(ws)
finally:
del ws # lose ref
duration = time() - last
if duration > 0.005: # 5ms since last release
next_time = timedelta(seconds=duration * 5) # 25ms gap
break
self.loop.add_timeout(
next_time, self.reevaluate_occupancy, worker_index=worker_index
)
except Exception:
logger.error("Error in reevaluate occupancy", exc_info=True)
raise
def _reevaluate_occupancy_worker(self, ws):
""" See reevaluate_occupancy """
old = ws.occupancy
new = 0
nbytes = 0
for ts in ws.processing:
duration = self.get_task_duration(ts)
comm = self.get_comm_cost(ts, ws)
ws.processing[ts] = duration + comm
new += duration + comm
ws.occupancy = new
self.total_occupancy += new - old
self.check_idle_saturated(ws)
# significant increase in duration
if (new > old * 1.3) and ("stealing" in self.extensions):
steal = self.extensions["stealing"]
for ts in ws.processing:
steal.remove_key_from_stealable(ts)
steal.put_key_in_stealable(ts)
def check_worker_ttl(self):
now = time()
for ws in self.workers.values():
if ws.last_seen < now - self.worker_ttl:
logger.warning(
"Worker failed to heartbeat within %s seconds. Closing: %s",
self.worker_ttl,
ws,
)
self.remove_worker(address=ws.address)
def check_idle(self):
if any(ws.processing for ws in self.workers.values()):
return
if self.unrunnable:
return
if not self.transition_log:
close = time() > self.time_started + self.idle_timeout
else:
last_task = self.transition_log[-1][-1]
close = time() > last_task + self.idle_timeout
if close:
self.loop.add_callback(self.close)
[docs] def adaptive_target(self, comm=None, target_duration="5s"):
""" Desired number of workers based on the current workload
This looks at the current running tasks and memory use, and returns a
number of desired workers. This is often used by adaptive scheduling.
Parameters
----------
target_duration: str
A desired duration of time for computations to take. This affects
how rapidly the scheduler will ask to scale.
See Also
--------
distributed.deploy.Adaptive
"""
target_duration = parse_timedelta(target_duration)
# CPU
cpu = math.ceil(
self.total_occupancy / target_duration
) # TODO: threads per worker
# Avoid a few long tasks from asking for many cores
tasks_processing = 0
for ws in self.workers.values():
tasks_processing += len(ws.processing)
if tasks_processing > cpu:
break
else:
cpu = min(tasks_processing, cpu)
if self.unrunnable and not self.workers:
cpu = max(1, cpu)
# Memory
limit_bytes = {addr: ws.memory_limit for addr, ws in self.workers.items()}
worker_bytes = [ws.nbytes for ws in self.workers.values()]
limit = sum(limit_bytes.values())
total = sum(worker_bytes)
if total > 0.6 * limit:
memory = 2 * len(self.workers)
else:
memory = 0
target = max(memory, cpu)
if target >= len(self.workers):
return target
else: # Scale down?
to_close = self.workers_to_close()
return len(self.workers) - len(to_close)
[docs]def decide_worker(ts, all_workers, valid_workers, objective):
"""
Decide which worker should take task *ts*.
We choose the worker that has the data on which *ts* depends.
If several workers have dependencies then we choose the less-busy worker.
Optionally provide *valid_workers* of where jobs are allowed to occur
(if all workers are allowed to take the task, pass True instead).
If the task requires data communication because no eligible worker has
all the dependencies already, then we choose to minimize the number
of bytes sent between workers. This is determined by calling the
*objective* function.
"""
deps = ts.dependencies
assert all(dts.who_has for dts in deps)
if ts.actor:
candidates = all_workers
else:
candidates = frequencies([ws for dts in deps for ws in dts.who_has])
if valid_workers is True:
if not candidates:
candidates = all_workers
else:
candidates = valid_workers & set(candidates)
if not candidates:
candidates = valid_workers
if not candidates:
if ts.loose_restrictions:
return decide_worker(ts, all_workers, True, objective)
else:
return None
if not candidates:
return None
if len(candidates) == 1:
return first(candidates)
return min(candidates, key=objective)
def validate_task_state(ts):
"""
Validate the given TaskState.
"""
assert ts.state in ALL_TASK_STATES or ts.state == "forgotten", ts
if ts.waiting_on:
assert ts.waiting_on.issubset(ts.dependencies), (
"waiting not subset of dependencies",
str(ts.waiting_on),
str(ts.dependencies),
)
if ts.waiters:
assert ts.waiters.issubset(ts.dependents), (
"waiters not subset of dependents",
str(ts.waiters),
str(ts.dependents),
)
for dts in ts.waiting_on:
assert not dts.who_has, ("waiting on in-memory dep", str(ts), str(dts))
assert dts.state != "released", ("waiting on released dep", str(ts), str(dts))
for dts in ts.dependencies:
assert ts in dts.dependents, (
"not in dependency's dependents",
str(ts),
str(dts),
str(dts.dependents),
)
if ts.state in ("waiting", "processing"):
assert dts in ts.waiting_on or dts.who_has, (
"dep missing",
str(ts),
str(dts),
)
assert dts.state != "forgotten"
for dts in ts.waiters:
assert dts.state in ("waiting", "processing"), (
"waiter not in play",
str(ts),
str(dts),
)
for dts in ts.dependents:
assert ts in dts.dependencies, (
"not in dependent's dependencies",
str(ts),
str(dts),
str(dts.dependencies),
)
assert dts.state != "forgotten"
assert (ts.processing_on is not None) == (ts.state == "processing")
assert bool(ts.who_has) == (ts.state == "memory"), (ts, ts.who_has)
if ts.state == "processing":
assert all(dts.who_has for dts in ts.dependencies), (
"task processing without all deps",
str(ts),
str(ts.dependencies),
)
assert not ts.waiting_on
if ts.who_has:
assert ts.waiters or ts.who_wants, (
"unneeded task in memory",
str(ts),
str(ts.who_has),
)
if ts.run_spec: # was computed
assert ts.type
assert isinstance(ts.type, str)
assert not any(ts in dts.waiting_on for dts in ts.dependents)
for ws in ts.who_has:
assert ts in ws.has_what, (
"not in who_has' has_what",
str(ts),
str(ws),
str(ws.has_what),
)
if ts.who_wants:
for cs in ts.who_wants:
assert ts in cs.wants_what, (
"not in who_wants' wants_what",
str(ts),
str(cs),
str(cs.wants_what),
)
if ts.actor:
if ts.state == "memory":
assert sum([ts in ws.actors for ws in ts.who_has]) == 1
if ts.state == "processing":
assert ts in ts.processing_on.actors
def validate_worker_state(ws):
for ts in ws.has_what:
assert ws in ts.who_has, (
"not in has_what' who_has",
str(ws),
str(ts),
str(ts.who_has),
)
for ts in ws.actors:
assert ts.state in ("memory", "processing")
def validate_state(tasks, workers, clients):
"""
Validate a current runtime state
This performs a sequence of checks on the entire graph, running in about
linear time. This raises assert errors if anything doesn't check out.
"""
for ts in tasks.values():
validate_task_state(ts)
for ws in workers.values():
validate_worker_state(ws)
for cs in clients.values():
for ts in cs.wants_what:
assert cs in ts.who_wants, (
"not in wants_what' who_wants",
str(cs),
str(ts),
str(ts.who_wants),
)
_round_robin = [0]
fast_tasks = {"rechunk-split", "shuffle-split"}
def heartbeat_interval(n):
"""
Interval in seconds that we desire heartbeats based on number of workers
"""
if n <= 10:
return 0.5
elif n < 50:
return 1
elif n < 200:
return 2
else:
return 5
class KilledWorker(Exception):
def __init__(self, task, last_worker):
super(KilledWorker, self).__init__(task, last_worker)
self.task = task
self.last_worker = last_worker
class WorkerStatusPlugin(SchedulerPlugin):
"""
An plugin to share worker status with a remote observer
This is used in cluster managers to keep updated about the status of the
scheduler.
"""
def __init__(self, scheduler, comm):
self.bcomm = BatchedSend(interval="5ms")
self.bcomm.start(comm)
self.scheduler = scheduler
self.scheduler.add_plugin(self)
def add_worker(self, worker=None, **kwargs):
ident = self.scheduler.workers[worker].identity()
del ident["metrics"]
del ident["last_seen"]
try:
self.bcomm.send(["add", {"workers": {worker: ident}}])
except CommClosedError:
self.scheduler.remove_plugin(self)
def remove_worker(self, worker=None, **kwargs):
try:
self.bcomm.send(["remove", worker])
except CommClosedError:
self.scheduler.remove_plugin(self)
def teardown(self):
self.bcomm.close()