137 lines
5.1 KiB
Python
137 lines
5.1 KiB
Python
import logging
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import json
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from threading import Event, Lock
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from app import app
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from data.database import CloseForLongOperation
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from workers.worker import Worker
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logger = logging.getLogger(__name__)
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class JobException(Exception):
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""" A job exception is an exception that is caused by something being malformed in the job. When
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a worker raises this exception the job will be terminated and the retry will not be returned
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to the queue. """
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pass
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class WorkerUnhealthyException(Exception):
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""" When this exception is raised, the worker is no longer healthy and will not accept any more
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work. When this is raised while processing a queue item, the item should be returned to the
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queue along with another retry. """
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pass
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class QueueWorker(Worker):
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def __init__(self, queue, poll_period_seconds=30, reservation_seconds=300,
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watchdog_period_seconds=60, retry_after_seconds=300):
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super(QueueWorker, self).__init__()
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self._poll_period_seconds = poll_period_seconds
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self._reservation_seconds = reservation_seconds
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self._watchdog_period_seconds = watchdog_period_seconds
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self._retry_after_seconds = retry_after_seconds
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self._stop = Event()
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self._terminated = Event()
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self._queue = queue
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self._current_item_lock = Lock()
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self.current_queue_item = None
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# Add the various operations.
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self.add_operation(self.poll_queue, self._poll_period_seconds)
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self.add_operation(self.update_queue_metrics,
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app.config['QUEUE_WORKER_METRICS_REFRESH_SECONDS'])
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self.add_operation(self.run_watchdog, self._watchdog_period_seconds)
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def process_queue_item(self, job_details):
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""" Processes the work for the given job. If the job fails and should be retried,
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this method should raise a WorkerUnhealthyException. If the job should be marked
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as permanently failed, it should raise a JobException. Otherwise, a successful return
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of this method will remove the job from the queue as completed.
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"""
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raise NotImplementedError('Workers must implement run.')
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def watchdog(self):
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""" Function that gets run once every watchdog_period_seconds. """
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pass
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def extend_processing(self, seconds_from_now, updated_data=None):
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with self._current_item_lock:
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if self.current_queue_item is not None:
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self._queue.extend_processing(self.current_queue_item, seconds_from_now,
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updated_data=updated_data)
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def run_watchdog(self):
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logger.debug('Running watchdog.')
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try:
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self.watchdog()
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except WorkerUnhealthyException as exc:
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logger.error('The worker has encountered an error via watchdog and will not take new jobs')
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logger.error(exc.message)
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self.mark_current_incomplete(restore_retry=True)
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self._stop.set()
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def poll_queue(self):
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logger.debug('Getting work item from queue.')
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with self._current_item_lock:
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self.current_queue_item = self._queue.get(processing_time=self._reservation_seconds)
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while True:
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# Retrieve the current item in the queue over which to operate. We do so under
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# a lock to make sure we are always retrieving an item when in a healthy state.
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current_queue_item = None
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with self._current_item_lock:
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current_queue_item = self.current_queue_item
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if current_queue_item is None:
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break
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logger.debug('Queue gave us some work: %s', current_queue_item.body)
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job_details = json.loads(current_queue_item.body)
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try:
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with CloseForLongOperation(app.config):
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self.process_queue_item(job_details)
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self.mark_current_complete()
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except JobException as jex:
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logger.warning('An error occurred processing request: %s', current_queue_item.body)
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logger.warning('Job exception: %s', jex)
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self.mark_current_incomplete(restore_retry=False)
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except WorkerUnhealthyException as exc:
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logger.error('The worker has encountered an error via the job and will not take new jobs')
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logger.error(exc.message)
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self.mark_current_incomplete(restore_retry=True)
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self._stop.set()
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if not self._stop.is_set():
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with self._current_item_lock:
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self.current_queue_item = self._queue.get(processing_time=self._reservation_seconds)
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if not self._stop.is_set():
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logger.debug('No more work.')
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def update_queue_metrics(self):
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self._queue.update_metrics()
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def mark_current_incomplete(self, restore_retry=False):
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with self._current_item_lock:
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if self.current_queue_item is not None:
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self._queue.incomplete(self.current_queue_item, restore_retry=restore_retry,
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retry_after=self._retry_after_seconds)
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self.current_queue_item = None
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def mark_current_complete(self):
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with self._current_item_lock:
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if self.current_queue_item is not None:
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self._queue.complete(self.current_queue_item)
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self.current_queue_item = None
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def ungracefully_terminated(self):
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# Give back the retry that we took for this queue item so that if it were down to zero
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# retries it will still be picked up by another worker
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self.mark_current_incomplete()
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