d5128cf51a
Instead of optionally creating a stopwatch when a provided timeout is not none (to avoid the stopwatch leftover() method raising a error) just allow the stopwatch leftover() method to not raise when no duration is provided to avoid these repeated styles of usage/checks in the first place. By default the leftover() method still raises an error (a new keyword argument is now accepted to turn off this behavior). Change-Id: If934ee6e6855adbb6975cd6ea41e273d40e73dac
575 lines
21 KiB
Python
575 lines
21 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import abc
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import collections
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from multiprocessing import managers
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import os
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import pickle
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from oslo_utils import excutils
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from oslo_utils import reflection
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from oslo_utils import timeutils
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from oslo_utils import uuidutils
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import six
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from six.moves import queue as compat_queue
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from taskflow import logging
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from taskflow import task as task_atom
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from taskflow.types import failure
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from taskflow.types import futures
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from taskflow.types import notifier
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from taskflow.types import timing
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from taskflow.utils import async_utils
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from taskflow.utils import threading_utils
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# Execution and reversion events.
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EXECUTED = 'executed'
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REVERTED = 'reverted'
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# See http://bugs.python.org/issue1457119 for why this is so complex...
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_PICKLE_ERRORS = [pickle.PickleError, TypeError]
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try:
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import cPickle as _cPickle
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_PICKLE_ERRORS.append(_cPickle.PickleError)
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except ImportError:
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pass
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_PICKLE_ERRORS = tuple(_PICKLE_ERRORS)
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_SEND_ERRORS = (IOError, EOFError)
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_UPDATE_PROGRESS = task_atom.EVENT_UPDATE_PROGRESS
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# Message types/kind sent from worker/child processes...
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_KIND_COMPLETE_ME = 'complete_me'
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_KIND_EVENT = 'event'
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LOG = logging.getLogger(__name__)
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def _execute_task(task, arguments, progress_callback=None):
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with notifier.register_deregister(task.notifier,
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_UPDATE_PROGRESS,
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callback=progress_callback):
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try:
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task.pre_execute()
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result = task.execute(**arguments)
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except Exception:
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# NOTE(imelnikov): wrap current exception with Failure
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# object and return it.
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result = failure.Failure()
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finally:
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task.post_execute()
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return (EXECUTED, result)
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def _revert_task(task, arguments, result, failures, progress_callback=None):
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arguments = arguments.copy()
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arguments[task_atom.REVERT_RESULT] = result
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arguments[task_atom.REVERT_FLOW_FAILURES] = failures
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with notifier.register_deregister(task.notifier,
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_UPDATE_PROGRESS,
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callback=progress_callback):
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try:
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task.pre_revert()
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result = task.revert(**arguments)
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except Exception:
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# NOTE(imelnikov): wrap current exception with Failure
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# object and return it.
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result = failure.Failure()
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finally:
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task.post_revert()
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return (REVERTED, result)
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class _ViewableSyncManager(managers.SyncManager):
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"""Manager that exposes its state as methods."""
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def is_shutdown(self):
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return self._state.value == managers.State.SHUTDOWN
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def is_running(self):
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return self._state.value == managers.State.STARTED
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class _Channel(object):
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"""Helper wrapper around a multiprocessing queue used by a worker."""
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def __init__(self, queue, identity):
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self._queue = queue
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self._identity = identity
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self._sent_messages = collections.defaultdict(int)
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self._pid = None
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@property
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def sent_messages(self):
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return self._sent_messages
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def put(self, message):
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# NOTE(harlowja): this is done in late in execution to ensure that this
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# happens in the child process and not the parent process (where the
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# constructor is called).
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if self._pid is None:
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self._pid = os.getpid()
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message.update({
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'sent_on': timeutils.utcnow(),
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'sender': {
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'pid': self._pid,
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'id': self._identity,
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},
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})
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if 'body' not in message:
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message['body'] = {}
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try:
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self._queue.put(message)
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except _PICKLE_ERRORS:
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LOG.warn("Failed serializing message %s", message, exc_info=True)
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return False
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except _SEND_ERRORS:
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LOG.warn("Failed sending message %s", message, exc_info=True)
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return False
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else:
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self._sent_messages[message['kind']] += 1
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return True
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class _WaitWorkItem(object):
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"""The piece of work that will executed by a process executor.
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This will call the target function, then wait until the tasks emitted
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events/items have been depleted before offically being finished.
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NOTE(harlowja): this is done so that the task function will *not* return
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until all of its notifications have been proxied back to its originating
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task. If we didn't do this then the executor would see this task as done
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and then potentially start tasks that are successors of the task that just
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finished even though notifications are still left to be sent from the
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previously finished task...
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"""
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def __init__(self, channel, barrier,
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func, task, *args, **kwargs):
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self._channel = channel
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self._barrier = barrier
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self._func = func
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self._task = task
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self._args = args
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self._kwargs = kwargs
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def _on_finish(self):
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sent_events = self._channel.sent_messages.get(_KIND_EVENT, 0)
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if sent_events:
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message = {
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'created_on': timeutils.utcnow(),
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'kind': _KIND_COMPLETE_ME,
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}
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if self._channel.put(message):
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watch = timing.StopWatch()
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watch.start()
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self._barrier.wait()
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LOG.blather("Waited %s seconds until task '%s' %s emitted"
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" notifications were depleted", watch.elapsed(),
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self._task, sent_events)
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def __call__(self):
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args = self._args
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kwargs = self._kwargs
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try:
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return self._func(self._task, *args, **kwargs)
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finally:
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self._on_finish()
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class _EventSender(object):
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"""Sends event information from a child worker process to its creator."""
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def __init__(self, channel):
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self._channel = channel
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def __call__(self, event_type, details):
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message = {
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'created_on': timeutils.utcnow(),
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'kind': _KIND_EVENT,
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'body': {
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'event_type': event_type,
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'details': details,
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},
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}
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self._channel.put(message)
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class _Target(object):
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"""An immutable helper object that represents a target of a message."""
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def __init__(self, task, barrier, identity):
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self.task = task
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self.barrier = barrier
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self.identity = identity
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# Counters used to track how many message 'kinds' were proxied...
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self.dispatched = collections.defaultdict(int)
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def __repr__(self):
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return "<%s at 0x%x targeting '%s' with identity '%s'>" % (
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reflection.get_class_name(self), id(self),
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self.task, self.identity)
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class _Dispatcher(object):
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"""Dispatches messages received from child worker processes."""
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# When the run() method is busy (typically in a thread) we want to set
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# these so that the thread can know how long to sleep when there is no
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# active work to dispatch.
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_SPIN_PERIODICITY = 0.01
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def __init__(self, dispatch_periodicity=None):
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if dispatch_periodicity is None:
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dispatch_periodicity = self._SPIN_PERIODICITY
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if dispatch_periodicity <= 0:
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raise ValueError("Provided dispatch periodicity must be greater"
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" than zero and not '%s'" % dispatch_periodicity)
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self._targets = {}
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self._dead = threading_utils.Event()
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self._dispatch_periodicity = dispatch_periodicity
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self._stop_when_empty = False
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def register(self, identity, target):
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self._targets[identity] = target
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def deregister(self, identity):
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try:
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target = self._targets.pop(identity)
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except KeyError:
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pass
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else:
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# Just incase set the barrier to unblock any worker...
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target.barrier.set()
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if LOG.isEnabledFor(logging.BLATHER):
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LOG.blather("Dispatched %s messages %s to target '%s' during"
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" the lifetime of its existence in the dispatcher",
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sum(six.itervalues(target.dispatched)),
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dict(target.dispatched), target)
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def reset(self):
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self._stop_when_empty = False
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self._dead.clear()
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if self._targets:
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leftover = set(six.iterkeys(self._targets))
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while leftover:
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self.deregister(leftover.pop())
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def interrupt(self):
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self._stop_when_empty = True
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self._dead.set()
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def _dispatch(self, message):
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if LOG.isEnabledFor(logging.BLATHER):
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LOG.blather("Dispatching message %s (it took %s seconds"
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" for it to arrive for processing after being"
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" sent)", message,
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timeutils.delta_seconds(message['sent_on'],
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timeutils.utcnow()))
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try:
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kind = message['kind']
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sender = message['sender']
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body = message['body']
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except (KeyError, ValueError, TypeError):
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LOG.warn("Badly formatted message %s received", message,
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exc_info=True)
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return
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target = self._targets.get(sender['id'])
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if target is None:
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# Must of been removed...
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return
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if kind == _KIND_COMPLETE_ME:
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target.dispatched[kind] += 1
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target.barrier.set()
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elif kind == _KIND_EVENT:
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task = target.task
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target.dispatched[kind] += 1
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task.notifier.notify(body['event_type'], body['details'])
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else:
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LOG.warn("Unknown message '%s' found in message from sender"
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" %s to target '%s'", kind, sender, target)
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def run(self, queue):
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watch = timing.StopWatch(duration=self._dispatch_periodicity)
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while (not self._dead.is_set() or
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(self._stop_when_empty and self._targets)):
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watch.restart()
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leftover = watch.leftover()
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while leftover:
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try:
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message = queue.get(timeout=leftover)
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except compat_queue.Empty:
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break
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else:
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self._dispatch(message)
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leftover = watch.leftover()
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leftover = watch.leftover()
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if leftover:
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self._dead.wait(leftover)
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@six.add_metaclass(abc.ABCMeta)
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class TaskExecutor(object):
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"""Executes and reverts tasks.
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This class takes task and its arguments and executes or reverts it.
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It encapsulates knowledge on how task should be executed or reverted:
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right now, on separate thread, on another machine, etc.
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"""
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@abc.abstractmethod
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def execute_task(self, task, task_uuid, arguments,
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progress_callback=None):
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"""Schedules task execution."""
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@abc.abstractmethod
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def revert_task(self, task, task_uuid, arguments, result, failures,
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progress_callback=None):
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"""Schedules task reversion."""
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def wait_for_any(self, fs, timeout=None):
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"""Wait for futures returned by this executor to complete."""
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return async_utils.wait_for_any(fs, timeout=timeout)
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def start(self):
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"""Prepare to execute tasks."""
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pass
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def stop(self):
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"""Finalize task executor."""
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pass
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class SerialTaskExecutor(TaskExecutor):
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"""Executes tasks one after another."""
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def __init__(self):
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self._executor = futures.SynchronousExecutor()
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def start(self):
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self._executor.restart()
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def stop(self):
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self._executor.shutdown()
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def execute_task(self, task, task_uuid, arguments, progress_callback=None):
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fut = self._executor.submit(_execute_task,
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task, arguments,
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progress_callback=progress_callback)
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fut.atom = task
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return fut
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def revert_task(self, task, task_uuid, arguments, result, failures,
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progress_callback=None):
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fut = self._executor.submit(_revert_task,
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task, arguments, result, failures,
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progress_callback=progress_callback)
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fut.atom = task
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return fut
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class ParallelTaskExecutor(TaskExecutor):
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"""Executes tasks in parallel.
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Submits tasks to an executor which should provide an interface similar
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to concurrent.Futures.Executor.
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"""
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#: Options this executor supports (passed in from engine options).
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OPTIONS = frozenset(['max_workers'])
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def __init__(self, executor=None, max_workers=None):
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self._executor = executor
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self._max_workers = max_workers
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self._own_executor = executor is None
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@abc.abstractmethod
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def _create_executor(self, max_workers=None):
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"""Called when an executor has not been provided to make one."""
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def _submit_task(self, func, task, *args, **kwargs):
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fut = self._executor.submit(func, task, *args, **kwargs)
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fut.atom = task
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return fut
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def execute_task(self, task, task_uuid, arguments, progress_callback=None):
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return self._submit_task(_execute_task, task, arguments,
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progress_callback=progress_callback)
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def revert_task(self, task, task_uuid, arguments, result, failures,
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progress_callback=None):
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return self._submit_task(_revert_task, task, arguments, result,
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failures, progress_callback=progress_callback)
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def start(self):
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if self._own_executor:
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if self._max_workers is not None:
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max_workers = self._max_workers
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else:
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max_workers = threading_utils.get_optimal_thread_count()
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self._executor = self._create_executor(max_workers=max_workers)
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def stop(self):
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if self._own_executor:
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self._executor.shutdown(wait=True)
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self._executor = None
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class ParallelThreadTaskExecutor(ParallelTaskExecutor):
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"""Executes tasks in parallel using a thread pool executor."""
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def _create_executor(self, max_workers=None):
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return futures.ThreadPoolExecutor(max_workers=max_workers)
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class ParallelProcessTaskExecutor(ParallelTaskExecutor):
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"""Executes tasks in parallel using a process pool executor.
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NOTE(harlowja): this executor executes tasks in external processes, so that
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implies that tasks that are sent to that external process are pickleable
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since this is how the multiprocessing works (sending pickled objects back
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and forth) and that the bound handlers (for progress updating in
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particular) are proxied correctly from that external process to the one
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that is alive in the parent process to ensure that callbacks registered in
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the parent are executed on events in the child.
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"""
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#: Options this executor supports (passed in from engine options).
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OPTIONS = frozenset(['max_workers', 'dispatch_periodicity'])
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def __init__(self, executor=None, max_workers=None,
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dispatch_periodicity=None):
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super(ParallelProcessTaskExecutor, self).__init__(
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executor=executor, max_workers=max_workers)
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self._manager = _ViewableSyncManager()
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self._dispatcher = _Dispatcher(
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dispatch_periodicity=dispatch_periodicity)
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# Only created after starting...
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self._worker = None
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self._queue = None
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def _create_executor(self, max_workers=None):
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return futures.ProcessPoolExecutor(max_workers=max_workers)
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def start(self):
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if threading_utils.is_alive(self._worker):
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raise RuntimeError("Worker thread must be stopped via stop()"
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" before starting/restarting")
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super(ParallelProcessTaskExecutor, self).start()
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# These don't seem restartable; make a new one...
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if self._manager.is_shutdown():
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self._manager = _ViewableSyncManager()
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if not self._manager.is_running():
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self._manager.start()
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self._dispatcher.reset()
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self._queue = self._manager.Queue()
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self._worker = threading_utils.daemon_thread(self._dispatcher.run,
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self._queue)
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self._worker.start()
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def stop(self):
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self._dispatcher.interrupt()
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super(ParallelProcessTaskExecutor, self).stop()
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if threading_utils.is_alive(self._worker):
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self._worker.join()
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self._worker = None
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self._queue = None
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self._dispatcher.reset()
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self._manager.shutdown()
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self._manager.join()
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def _rebind_task(self, task, clone, channel, progress_callback=None):
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# Creates and binds proxies for all events the task could receive
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# so that when the clone runs in another process that this task
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# can recieve the same notifications (thus making it look like the
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# the notifications are transparently happening in this process).
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needed = set()
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for (event_type, listeners) in task.notifier.listeners_iter():
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if listeners:
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needed.add(event_type)
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if progress_callback is not None:
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needed.add(_UPDATE_PROGRESS)
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if needed:
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sender = _EventSender(channel)
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for event_type in needed:
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clone.notifier.register(event_type, sender)
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def _submit_task(self, func, task, *args, **kwargs):
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"""Submit a function to run the given task (with given args/kwargs).
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NOTE(harlowja): Adjust all events to be proxies instead since we want
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those callbacks to be activated in this process, not in the child,
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also since typically callbacks are functors (or callables) we can
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not pickle those in the first place...
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To make sure people understand how this works, the following is a
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lengthy description of what is going on here, read at will:
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So to ensure that we are proxying task triggered events that occur
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in the executed subprocess (which will be created and used by the
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thing using the multiprocessing based executor) we need to establish
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a link between that process and this process that ensures that when a
|
|
event is triggered in that task in that process that a corresponding
|
|
event is triggered on the original task that was requested to be ran
|
|
in this process.
|
|
|
|
To accomplish this we have to create a copy of the task (without
|
|
any listeners) and then reattach a new set of listeners that will
|
|
now instead of calling the desired listeners just place messages
|
|
for this process (a dispatcher thread that is created in this class)
|
|
to dispatch to the original task (using a common queue + per task
|
|
sender identity/target that is used and associated to know which task
|
|
to proxy back too, since it is possible that there many be *many*
|
|
subprocess running at the same time, each running a different task
|
|
and using the same common queue to submit messages back to).
|
|
|
|
Once the subprocess task has finished execution, the executor will
|
|
then trigger a callback that will remove the task + target from the
|
|
dispatcher (which will stop any further proxying back to the original
|
|
task).
|
|
"""
|
|
progress_callback = kwargs.pop('progress_callback', None)
|
|
clone = task.copy(retain_listeners=False)
|
|
identity = uuidutils.generate_uuid()
|
|
target = _Target(task, self._manager.Event(), identity)
|
|
channel = _Channel(self._queue, identity)
|
|
self._rebind_task(task, clone, channel,
|
|
progress_callback=progress_callback)
|
|
|
|
def register():
|
|
if progress_callback is not None:
|
|
task.notifier.register(_UPDATE_PROGRESS, progress_callback)
|
|
self._dispatcher.register(identity, target)
|
|
|
|
def deregister():
|
|
if progress_callback is not None:
|
|
task.notifier.deregister(_UPDATE_PROGRESS, progress_callback)
|
|
self._dispatcher.deregister(identity)
|
|
|
|
register()
|
|
work = _WaitWorkItem(channel, target.barrier,
|
|
func, clone, *args, **kwargs)
|
|
try:
|
|
fut = self._executor.submit(work)
|
|
except RuntimeError:
|
|
with excutils.save_and_reraise_exception():
|
|
deregister()
|
|
|
|
fut.atom = task
|
|
fut.add_done_callback(lambda fut: deregister())
|
|
return fut
|