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Posted to commits@airflow.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2018/12/17 23:52:01 UTC
[jira] [Commented] (AIRFLOW-1491) Celery executor restarts result
in duplicate tasks
[ https://issues.apache.org/jira/browse/AIRFLOW-1491?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16723486#comment-16723486 ]
ASF GitHub Bot commented on AIRFLOW-1491:
-----------------------------------------
stale[bot] closed pull request #2503: AIRFLOW-1491 Check celery queue before scheduling commands
URL: https://github.com/apache/incubator-airflow/pull/2503
This is a PR merged from a forked repository.
As GitHub hides the original diff on merge, it is displayed below for
the sake of provenance:
As this is a foreign pull request (from a fork), the diff is supplied
below (as it won't show otherwise due to GitHub magic):
diff --git a/airflow/executors/base_executor.py b/airflow/executors/base_executor.py
index 7a4065eb07..8a3a71ad46 100644
--- a/airflow/executors/base_executor.py
+++ b/airflow/executors/base_executor.py
@@ -132,7 +132,7 @@ def heartbeat(self):
self.sync()
def change_state(self, key, state):
- self.running.pop(key)
+ self.running.pop(key, None)
self.event_buffer[key] = state
def fail(self, key):
diff --git a/airflow/executors/celery_executor.py b/airflow/executors/celery_executor.py
index 17c343bd4a..5654685815 100644
--- a/airflow/executors/celery_executor.py
+++ b/airflow/executors/celery_executor.py
@@ -13,6 +13,7 @@
# limitations under the License.
from builtins import object
+import itertools
import logging
import subprocess
import ssl
@@ -20,6 +21,7 @@
import traceback
from celery import Celery
+from celery.result import AsyncResult
from celery import states as celery_states
from airflow.exceptions import AirflowConfigException, AirflowException
@@ -83,6 +85,26 @@ def execute_command(command):
raise AirflowException('Celery command failed')
+def recover_command(command):
+ """Recover the celery AsyncResult object for a command, if possible.
+
+ Note:
+ - We use iterables and generators to minimize backend calls.
+ - Functionality is dependent on features presented by the celery
+ backend in use.
+ """
+ insp = app.control.inspect()
+ task_providers = [insp.active, insp.scheduled, insp.reserved]
+ task_lists = (
+ itertools.chain.from_iterable(tp().values())
+ for tp in task_providers)
+ tasks = itertools.chain.from_iterable(task_lists)
+ for task in tasks:
+ if task['args'] == [command]:
+ return AsyncResult(id=task['id'], app=app)
+ return None
+
+
class CeleryExecutor(BaseExecutor):
"""
CeleryExecutor is recommended for production use of Airflow. It allows
@@ -98,17 +120,29 @@ def start(self):
self.last_state = {}
def execute_async(self, key, command, queue=DEFAULT_QUEUE):
- self.logger.info( "[celery] queuing {key} through celery, "
- "queue={queue}".format(**locals()))
- self.tasks[key] = execute_command.apply_async(
- args=[command], queue=queue)
+ if key in self.tasks:
+ self.logger.warning('[celery] existing command scheduled '
+ 'for {key}'.format(key=key))
+ return
+
+ async_command = recover_command(command)
+ if async_command is not None:
+ self.logger.warning('[celery] recovering already scheduled '
+ 'command {command}'.format(command=command))
+ else:
+ self.logger.info('[celery] queuing {key} through celery, '
+ 'queue={queue}'.format(key=key, queue=queue))
+ async_command = execute_command.apply_async(
+ args=[command], queue=queue)
+
+ self.tasks[key] = async_command
self.last_state[key] = celery_states.PENDING
def sync(self):
self.logger.debug(
"Inquiring about {} celery task(s)".format(len(self.tasks)))
- for key, async in list(self.tasks.items()):
+ for key, async in self.tasks.items():
try:
state = async.state
if self.last_state[key] != state:
@@ -129,7 +163,7 @@ def sync(self):
self.last_state[key] = async.state
except Exception as e:
logging.error("Error syncing the celery executor, ignoring "
- "it:\n{}\n".format(e, traceback.format_exc()))
+ "it:\n{}\n{}".format(e, traceback.format_exc()))
def end(self, synchronous=False):
if synchronous:
diff --git a/tests/executors/celery_executor.py b/tests/executors/celery_executor.py
new file mode 100644
index 0000000000..61c62eabd8
--- /dev/null
+++ b/tests/executors/celery_executor.py
@@ -0,0 +1,143 @@
+# -*- coding: utf-8 -*-
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+
+from celery import states as cstates
+
+from airflow.executors.celery_executor import CeleryExecutor
+
+try:
+ from unittest import mock
+except ImportError:
+ try:
+ import mock
+ except ImportError:
+ mock = None
+
+
+class CeleryExecutorTest(unittest.TestCase):
+ """Unit tests for the CeleryExecutor."""
+
+ @unittest.skipIf(mock is None, 'mock package not present')
+ @mock.patch('airflow.executors.celery_executor.time')
+ @mock.patch('airflow.executors.celery_executor.execute_command')
+ @mock.patch('airflow.executors.celery_executor.app')
+ def test_executor(self, app, execute_command, time):
+ insp = mock.MagicMock(name='inspector')
+ insp.active.return_value = {}
+ insp.scheduled.return_value = {}
+ insp.reserved.return_value = {}
+ app.control.inspect.return_value = insp
+
+ async1 = mock.MagicMock(name='async1')
+ async1.state = cstates.PENDING
+ async2 = mock.MagicMock(name='async2')
+ async2.state = cstates.FAILURE
+ execute_command.apply_async.side_effect = [async1, async2]
+
+ executor = CeleryExecutor()
+ executor.start()
+
+ executor.execute_async(key='one', command='echo 1')
+ executor.execute_async(key='two', command='echo 2', queue='other')
+
+ self.assertEquals(executor.tasks, {'one': async1, 'two': async2})
+ self.assertEquals(executor.last_state,
+ {'one': cstates.PENDING, 'two': cstates.PENDING})
+
+ self.assertEquals(execute_command.mock_calls, [
+ mock.call.apply_async(args=['echo 1'], queue='default'),
+ mock.call.apply_async(args=['echo 2'], queue='other'),
+ ])
+ self.assertFalse(async1.mock_calls)
+ self.assertFalse(async2.mock_calls)
+ self.assertFalse(time.mock_calls)
+
+ executor.sync()
+
+ self.assertFalse(async1.mock_calls)
+ self.assertFalse(async2.mock_calls)
+
+ self.assertEquals(executor.tasks, {'one': async1})
+ self.assertEquals(executor.last_state,
+ {'one': cstates.PENDING, 'two': cstates.FAILURE})
+
+ @unittest.skipIf(mock is None, 'mock package not present')
+ @mock.patch('airflow.executors.celery_executor.execute_command')
+ @mock.patch('airflow.executors.celery_executor.app')
+ def test_repeat_key(self, app, execute_command):
+ insp = mock.MagicMock(name='inspector')
+ insp.active.return_value = {}
+ insp.scheduled.return_value = {}
+ insp.reserved.return_value = {}
+ app.control.inspect.return_value = insp
+
+ executor = CeleryExecutor()
+ executor.start()
+
+ executor.execute_async(key='one', command='echo 1')
+ executor.execute_async(key='two', command='echo 2', queue='other')
+ executor.execute_async(key='one', command='echo 3', queue='other')
+
+ self.assertEquals(execute_command.mock_calls, [
+ mock.call.apply_async(args=['echo 1'], queue='default'),
+ mock.call.apply_async(args=['echo 2'], queue='other'),
+ ])
+
+ @unittest.skipIf(mock is None, 'mock package not present')
+ @mock.patch('airflow.executors.celery_executor.AsyncResult')
+ @mock.patch('airflow.executors.celery_executor.execute_command')
+ @mock.patch('airflow.executors.celery_executor.app')
+ def test_existing_command(self, app, execute_command, result):
+ insp = mock.MagicMock(name='inspector')
+ insp.active.return_value = {
+ 'worker1': [{
+ 'id': 'id1',
+ 'args': ['echo 1']}],
+ }
+ insp.scheduled.return_value = {
+ 'worker2': [{
+ 'id': 'id2',
+ 'args': ['echo 2']}],
+ }
+ insp.reserved.return_value = {
+ 'worker3': [{
+ 'id': 'id3',
+ 'args': ['echo 3']}],
+ }
+ app.control.inspect.return_value = insp
+
+ executor = CeleryExecutor()
+ executor.start()
+
+ executor.execute_async(key='one', command='echo 1')
+ executor.execute_async(key='two', command='echo 2', queue='other')
+ executor.execute_async(key='three', command='echo 3', queue='other')
+ executor.execute_async(key='four', command='echo 4')
+
+ self.assertEquals(execute_command.mock_calls, [
+ mock.call.apply_async(args=['echo 4'], queue='default'),
+ ])
+ self.assertEquals(result.mock_calls, [
+ mock.call(id='id1', app=app),
+ mock.call(id='id2', app=app),
+ mock.call(id='id3', app=app),
+ ])
+ self.assertEquals(executor.tasks, {
+ 'one': result.return_value,
+ 'two': result.return_value,
+ 'three': result.return_value,
+ 'four': execute_command.apply_async.return_value,
+ })
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> Celery executor restarts result in duplicate tasks
> --------------------------------------------------
>
> Key: AIRFLOW-1491
> URL: https://issues.apache.org/jira/browse/AIRFLOW-1491
> Project: Apache Airflow
> Issue Type: Bug
> Reporter: George Leslie-Waksman
> Assignee: George Leslie-Waksman
> Priority: Major
>
> Since the Celery executor uses internal state to determine what it has queued already, anything that wipes the executor state (such as a scheduler restart) will result in rescheduling of tasks.
> This bug exacerbates a number of task scheduling race conditions and can result in duplicate task execution.
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