ce5172ca52
Instead of returning whether the conductor is still dispatching return whether the stop was successful or whether it was not. This matches better with the expected semantics of the stop routine. Change-Id: Iccdca017e174adbd8eb3c093c6d0ea0c570792f5
151 lines
6.3 KiB
Python
151 lines
6.3 KiB
Python
# -*- coding: utf-8 -*-
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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 logging
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import threading
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import six
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from taskflow.conductors import base
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from taskflow import exceptions as excp
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from taskflow.listeners import logging as logging_listener
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from taskflow.utils import lock_utils
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from taskflow.utils import misc
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LOG = logging.getLogger(__name__)
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WAIT_TIMEOUT = 0.5
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NO_CONSUME_EXCEPTIONS = tuple([
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excp.ExecutionFailure,
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excp.StorageFailure,
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])
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class SingleThreadedConductor(base.Conductor):
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"""A conductor that runs jobs in its own dispatching loop.
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This conductor iterates over jobs in the provided jobboard (waiting for
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the given timeout if no jobs exist) and attempts to claim them, work on
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those jobs in its local thread (blocking further work from being claimed
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and consumed) and then consume those work units after completetion. This
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process will repeat until the conductor has been stopped or other critical
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error occurs.
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NOTE(harlowja): consumption occurs even if a engine fails to run due to
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a task failure. This is only skipped when an execution failure or
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a storage failure occurs which are *usually* correctable by re-running on
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a different conductor (storage failures and execution failures may be
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transient issues that can be worked around by later execution). If a job
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after completing can not be consumed or abandoned the conductor relies
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upon the jobboard capabilities to automatically abandon these jobs.
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"""
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def __init__(self, name, jobboard, engine_conf, persistence,
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wait_timeout=None):
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super(SingleThreadedConductor, self).__init__(name, jobboard,
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engine_conf,
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persistence)
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if wait_timeout is None:
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wait_timeout = WAIT_TIMEOUT
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if isinstance(wait_timeout, (int, float) + six.string_types):
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self._wait_timeout = misc.Timeout(float(wait_timeout))
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elif isinstance(wait_timeout, misc.Timeout):
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self._wait_timeout = wait_timeout
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else:
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raise ValueError("Invalid timeout literal: %s" % (wait_timeout))
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self._dead = threading.Event()
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@lock_utils.locked
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def stop(self, timeout=None):
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"""Requests the conductor to stop dispatching and returns whether the
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stop request was successfully completed. If the dispatching is still
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occurring then False is returned otherwise True will be returned to
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signal that the conductor is no longer dispatching job requests.
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NOTE(harlowja): If a timeout is provided the dispatcher loop may
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not have ceased by the timeout reached (the request to cease will
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be honored in the future) and False will be returned indicating this.
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"""
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self._wait_timeout.interrupt()
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self._dead.wait(timeout)
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return self._dead.is_set()
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@property
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def dispatching(self):
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return not self._dead.is_set()
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def _dispatch_job(self, job):
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engine = self._engine_from_job(job)
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consume = True
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with logging_listener.LoggingListener(engine, log=LOG):
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LOG.debug("Dispatching engine %s for job: %s", engine, job)
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try:
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engine.run()
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except excp.WrappedFailure as e:
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if all((f.check(*NO_CONSUME_EXCEPTIONS) for f in e)):
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LOG.warn("Job execution failed (consumption being"
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" skipped): %s", job, exc_info=True)
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consume = False
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else:
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LOG.warn("Job execution failed: %s", job, exc_info=True)
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except NO_CONSUME_EXCEPTIONS:
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LOG.warn("Job execution failed (consumption being"
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" skipped): %s", job, exc_info=True)
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consume = False
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except Exception:
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LOG.warn("Job execution failed: %s", job, exc_info=True)
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else:
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LOG.info("Job completed successfully: %s", job)
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return consume
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def run(self):
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self._dead.clear()
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try:
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while True:
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if self._wait_timeout.is_stopped():
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break
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dispatched = 0
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for job in self._jobboard.iterjobs():
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if self._wait_timeout.is_stopped():
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break
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LOG.debug("Trying to claim job: %s", job)
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try:
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self._jobboard.claim(job, self._name)
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except (excp.UnclaimableJob, excp.NotFound):
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LOG.debug("Job already claimed or consumed: %s", job)
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continue
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consume = False
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try:
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consume = self._dispatch_job(job)
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except Exception:
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LOG.warn("Job dispatching failed: %s", job,
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exc_info=True)
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else:
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dispatched += 1
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try:
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if consume:
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self._jobboard.consume(job, self._name)
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else:
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self._jobboard.abandon(job, self._name)
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except excp.JobFailure:
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if consume:
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LOG.warn("Failed job consumption: %s", job,
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exc_info=True)
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else:
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LOG.warn("Failed job abandonment: %s", job,
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exc_info=True)
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if dispatched == 0 and not self._wait_timeout.is_stopped():
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self._wait_timeout.wait()
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finally:
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self._dead.set()
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