Airflow: Save Tons of Money by Using Deferrable Operators

This talk is from Open Source Summit 2022

Apache Airflow 2.2 introduced the concept of Deferrable Tasks that uses Python's async feature.

All the Airflow sensors and poll-based operators can be hugely optimized to save tons of money by freeing up worker slots when polling.

This session will cover the following topics: - Introduction to the concept of deferrable operator

- Why do we need them?
- When to use them?
- How does it work?
- Writing Custom deferrable operators & Sensors

Transcript

1. Airflow: Deferrable “Async” Operators How you can save tons of money!! Kaxil Naik Open Source Summit 2022
2. Who am I? • Committer & PMC Member of Apache Airflow • Director of Airflow Engineering @ Astronomer @kaxil
3. What is Apache Airflow?
4. A platform to programmatically author, schedule, and monitor workflows
5. Example DAG
6. Why deferrable operators? The problem around current operators & sensors What are they? And how do they work? Available async operators How to find & use the available async operators
7. Why deferrable operators?
8. Scheduler Time Scheduler Worker
9. Scheduler Time Scheduler Submit Spark Job Typical Operator Poll Spark cluster Job Completion Worker
10. Scheduler Time Scheduler Typical Sensor Wait for files to arrive in S3 Arrived! Worker
11. Scheduler Time Scheduler What a waste! Wait for files to arrive in S3 Arrived! Worker Submit Spark Job Poll Spark cluster Job Completion Wasted resources Wasted resources Operator Sensor
12. Scheduler Time Scheduler What a waste! Wait for files to arrive in S3 Arrived! Worker Submit Spark Job Poll Spark cluster Job Completion Wasted resources Wasted resources Operator Sensor
13. Time Polling for Spark Job completion Done! Multiple Sensors Wait for files to arrive in S3 Done! Polling for Bigquery Job completion Done! Polling for Spark Job completion Done! Wait for files to arrive in S3 Done! Wait for files to arrive in GCS Done! Imagine the Cost! Multiple worker slots Blocked !!
14. What are deferrable operators?
15. Scheduler Time Scheduler Worker Triggerer Worker
16. Scheduler Time Scheduler Submit Spark Job Async Operator Free slot Job Completion Worker Poll Spark cluster Triggerer
17. Scheduler Time Scheduler Task 1 Worker Slot (Sync vs Async) Task 2 Sync Operator Async Operator Task 1 Task 2 Task 3 Task 2 Task 1 Task 4
18. Scheduler Time Scheduler Submit Spark Job Async Operator Free slot Job Completion Worker Poll Spark cluster Triggerer Trigger - a new concept
19. Task runs on the Worker, then “defers” itself Example: Submit an API call and stores job_id in DB Runs on Triggerer Async polling until the criteria is met, stores response in DB Back to the Worker To show response in the logs and set Task state
20. Trigger is different than Operator
21. Must be asynchronous & quick So Triggerer can run thousands of them per CPU core Should not persistent state So we can shuffle them around between Triggerers as needed Must support running multiple copies of itself For reliability during network partitions
22. class DateTimeTrigger(BaseTrigger): def __init__(self, moment: datetime.datetime): super().__init__() self.moment = moment def serialize(self): return ("mymodule.DateTimeTrigger", {"moment": self.moment}) async def run(self): while self.moment > timezone.utcnow(): await asyncio.sleep(1) yield TriggerEvent(self.moment)
23. class WaitOneHourSensor(BaseSensorOperator): def execute(self, context): self.defer( trigger=TimeDeltaTrigger(timedelta(hours=1)), method_name="execute_complete", ) def execute_complete(self, context, event=None): # We have no more work to do here. Mark as complete. return
24. Available Deferrable Operators
25. Core Airflow & Providers https://github.com/apache/airflow/ Astronomer Providers https://github.com/astronomer/astronomer-providers 50+ async operators
26. Astronomer Providers https://github.com/astronomer/astronomer-providers 50+ async operators Built and maintained with ❤ by Astronomer Apache 2 licensed & Open-source Drop-in replacements of “sync” Operators Openlineage support
27. Astronomer Providers https://github.com/astronomer/astronomer-providers Async Operators available for: • AWS, Google Cloud, Microsoft Azure • Databricks, Snowflake • Kubernetes, Apache Livy, Apache Hive • HTTP, Filesystem from astronomer.providers.amazon.aws.sensors.s3 import S3KeySensorAsync as S3KeySensor
28. from astronomer.providers.amazon.aws.sensors.s3 import S3KeySensorAsync as S3KeySensor waiting_for_s3_key = S3KeySensor( task_id="waiting_for_s3_key" , bucket_key="sample_key.txt" , wildcard_match =False, bucket_name="sample-bucket" , )
29. Caveats when building one
30. More cost benefits when polling takes longer time We've seen over a 90% reduction in resources for a 10 min wait Not everything can be deferred It must be an external event/system with a unique identifier Triggerer logs are not visible in the Webserver/UI Only task logs from workers are displayed on UI
31. Thank You @kaxil