为什么我的 Airflow 任务“从外部设置为失败"? [英] Why are my Airflow tasks being "externally set to failed"?

问题描述

我使用的是 Airflow 2.0.0，我的任务偶尔会被外部"终止；运行几秒钟或几分钟后.这些任务通常会成功运行(对于通过 airflow tasks test ... 启动的手动任务和计划的 DAG 运行)，所以我相信这与我的 DAG 代码无关.

I'm using Airflow 2.0.0, and my tasks are sporadically being killed "externally" after running for a few seconds or minutes. The tasks usually run successfully (both for manual task initiated via airflow tasks test ... and for scheduled DAG runs), so I believe this is not related to my DAG code.

当任务失败时，这似乎是任务日志中的关键错误:

When tasks fail, this seems to be the key error from the task logs:

{local_task_job.py:170} WARNING - State of this instance has been externally set to failed. Terminating instance.

[2020-12-20 11:26:11,448] {taskinstance.py:826} INFO - Dependencies all met for <TaskInstance: daily_backups.run_backupper 2020-12-19T02:00:00+00:00 [queued]>
[2020-12-20 11:26:11,473] {taskinstance.py:826} INFO - Dependencies all met for <TaskInstance: daily_backups.run_backupper 2020-12-19T02:00:00+00:00 [queued]>
[2020-12-20 11:26:11,473] {taskinstance.py:1017} INFO - 
--------------------------------------------------------------------------------
[2020-12-20 11:26:11,473] {taskinstance.py:1018} INFO - Starting attempt 3 of 3
[2020-12-20 11:26:11,473] {taskinstance.py:1019} INFO - 
--------------------------------------------------------------------------------
[2020-12-20 11:26:11,506] {taskinstance.py:1038} INFO - Executing <Task(PythonOperator): run_backupper> on 2020-12-19T02:00:00+00:00
[2020-12-20 11:26:11,509] {standard_task_runner.py:51} INFO - Started process 12059 to run task
[2020-12-20 11:26:11,515] {standard_task_runner.py:75} INFO - Running: ['airflow', 'tasks', 'run', 'daily_backups', 'run_backupper', '2020-12-19T02:00:00+00:00', '--job-id', '22', '--pool', 'default_pool', '--raw', '--subdir', 'DAGS_FOLDER/backupper/daily_backups.py', '--cfg-path', '/tmp/tmpnfmqtorg']
[2020-12-20 11:26:11,517] {standard_task_runner.py:76} INFO - Job 22: Subtask run_backupper
[2020-12-20 11:26:11,609] {logging_mixin.py:103} INFO - Running <TaskInstance: daily_backups.run_backupper 2020-12-19T02:00:00+00:00 [running]> on host localhost
[2020-12-20 11:26:11,742] {taskinstance.py:1232} INFO - Exporting the following env vars:
AIRFLOW_CTX_DAG_OWNER=<user>
AIRFLOW_CTX_DAG_ID=daily_backups
AIRFLOW_CTX_TASK_ID=run_backupper
AIRFLOW_CTX_EXECUTION_DATE=2020-12-19T02:00:00+00:00
AIRFLOW_CTX_DAG_RUN_ID=scheduled__2020-12-19T02:00:00+00:00
...
... my job's logs, indicating that the job is running healthily ...
...
[2020-12-20 11:26:16,587] {local_task_job.py:170} WARNING - State of this instance has been externally set to failed. Terminating instance.
[2020-12-20 11:26:16,593] {process_utils.py:95} INFO - Sending Signals.SIGTERM to GPID 12059
[2020-12-20 11:27:16,609] {process_utils.py:108} WARNING - process psutil.Process(pid=12059, name='airflow task runner: daily_backups run_backupper 2020-12-19T02:00:00+00:00 22', status='sleeping', started='11:26:11') did not respond to SIGTERM. Trying SIGKILL
[2020-12-20 11:27:16,618] {process_utils.py:61} INFO - Process psutil.Process(pid=12059, name='airflow task runner: daily_backups run_backupper 2020-12-19T02:00:00+00:00 22', status='terminated', exitcode=<Negsignal.SIGKILL: -9>, started='11:26:11') (12059) terminated with exit code Negsignal.SIGKILL
[2020-12-20 11:27:16,618] {local_task_job.py:118} INFO - Task exited with return code Negsignal.SIGKILL

日志中的最后几行不一致.这是一个不同的版本，用于先前尝试失败的同一任务:

The final few lines in the logs are not consistent. Here is a different version, for the same task that failed in an earlier attempt:

... same stuff as before ...
[2020-12-20 02:01:12,689] {local_task_job.py:170} WARNING - State of this instance has been externally set to failed. Terminating instance.
[2020-12-20 02:01:12,695] {process_utils.py:95} INFO - Sending Signals.SIGTERM to GPID 24442
[2020-12-20 02:02:00,462] {taskinstance.py:1214} ERROR - Received SIGTERM. Terminating subprocesses.
[2020-12-20 02:02:00,498] {process_utils.py:61} INFO - Process psutil.Process(pid=24442, status='terminated', exitcode=0, started='02:00:10') (24442) terminated with exit code 0
[2020-12-20 02:02:00,499] {local_task_job.py:118} INFO - Task exited with return code 0

我怀疑在这种情况下，脚本能够及时响应 SIGTERM，而在前一种情况下，它在长时间运行的查询中被阻止并且无法干净地终止.

I suspect in this case the script was able to respond to the SIGTERM in time, whereas in the previous case it was blocked on a long-running query and was not able to terminate cleanly.

推荐答案

我认为问题在于调度程序健康检查阈值设置为小于调度程序心跳间隔.

在我的配置中，我将 scheduler_health_check_threshold 设置为 30 秒，将 scheduler_heartbeat_sec 设置为 60 秒.在检查孤立任务(它本身由不同的参数 orphaned_tasks_check_interval 控制)期间，调度程序心跳被确定为超过 30 秒，这是有道理的，因为它每 60 秒才心跳一次.因此，调度程序被推断为不健康并因此被终止.

In my config I had set scheduler_health_check_threshold to 30 seconds and scheduler_heartbeat_sec to 60 seconds. During the check for orphaned tasks (itself governed by a different parameter, orphaned_tasks_check_interval), the scheduler heartbeat was determined to be older than 30 seconds, which makes sense, because it was only heartbeating every 60 seconds. Thus the scheduler was inferred to be unhealthy and was therefore terminated.

大约在失败时，我可以在 /var/log/syslog

Around the time of the failure, I could see messages like these in /var/log/syslog

Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,368] {scheduler_job.py:1751} INFO - Resetting orphaned tasks for active dag runs
Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,373] {scheduler_job.py:1764} INFO - Marked 1 SchedulerJob instances as failed
Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,381] {scheduler_job.py:1805} INFO - Reset the following 1 orphaned TaskInstances:
Dec 20 11:26:14 localhost bash[11545]: #011<TaskInstance: daily_backups.run_backupper 2020-12-19 02:00:00+00:00 [running]>
Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,571] {scheduler_job.py:938} INFO - 1 tasks up for execution:
Dec 20 11:26:14 localhost bash[11545]: #011<TaskInstance: daily_backups.run_backupper 2020-12-19 02:00:00+00:00 [scheduled]>
Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,574] {scheduler_job.py:972} INFO - Figuring out tasks to run in Pool(name=default_pool) with 128 open slots and 1 task instances ready to be queued
Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,575] {scheduler_job.py:999} INFO - DAG daily_backups has 0/16 running and queued tasks
Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,575] {scheduler_job.py:1060} INFO - Setting the following tasks to queued state:
Dec 20 11:26:14 localhost bash[11545]: #011<TaskInstance: daily_backups.run_backupper 2020-12-19 02:00:00+00:00 [scheduled]>
Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,578] {scheduler_job.py:1102} INFO - Sending TaskInstanceKey(dag_id='daily_backups', task_id='run_backupper', execution_date=datetime.datetime(2020, 12, 19, 2, 0, tzinfo=Timezone('UTC')), try_number=4) to executor with priority 2 and queue default
Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,578] {base_executor.py:79} INFO - Adding to queue: ['airflow', 'tasks', 'run', 'daily_backups', 'run_backupper', '2020-12-19T02:00:00+00:00', '--local', '--pool', 'default_pool', '--subdir', '/storage/airflow/dags/backupper/daily_backups.py']
Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,581] {local_executor.py:81} INFO - QueuedLocalWorker running ['airflow', 'tasks', 'run', 'daily_backups', 'run_backupper', '2020-12-19T02:00:00+00:00', '--local', '--pool', 'default_pool', '--subdir', '/storage/airflow/dags/backupper/daily_backups.py']
Dec 20 11:26:14 localhost bash[11545]: [2020-12-20 11:26:14,707] {dagbag.py:440} INFO - Filling up the DagBag from /storage/airflow/dags/backupper/daily_backups.py
Dec 20 11:26:15 localhost bash[11545]: Running <TaskInstance: daily_backups.run_backupper 2020-12-19T02:00:00+00:00 [queued]> on host localhost

并且时间戳与我的任务收到的​​ SIGTERM 非常吻合.我猜因为 SchedulerJob 被标记为失败，那么运行我的实际任务的 TaskInstance 被认为是孤立的，因此被标记为终止.同时它安排了一次新的尝试 (try_number=4).

and the timestamps coincide closely with the SIGTERM received by my task. I guess that since the SchedulerJob was marked as failed, then the TaskInstance running my actual task was considered an orphan, and thus marked for termination. At the same time it scheduled a new attempt (try_number=4).

将 scheduler_health_check_threshold 增加到 120 秒并重新启动调度程序/网络服务器服务似乎解决了我的问题.

Increasing the scheduler_health_check_threshold to 120 seconds and restarting the scheduler/webserver services appears to have resolved my issue.

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