4 Ways to Effectively Debug Data Pipelines in Apache Beam

Save time debugging by running unit tests before deploying to the cloud, by using modular construction, and by programmatically generating unique labels

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Apache Beam is an open source framework that is useful for cleaning and processing data at scale. It is also useful for processing streaming data in real time. In fact, you can even develop in Apache Beam on your laptop and deploy it to Google Cloud for processing (the Google Cloud version is called DataFlow).

Beyond this, Beam touches into the world of artificial intelligence. More formally, it is used as a part of a machine learning pipelines or in automated deployments of machine learning models ( MLOps ). As a specific example, Beam could be used to clean up spelling errors or punctuation from a Twitter data before the data is sent to a machine learning model that determines if the tweet represents emotion that is happy or sad.

One of the challenges though when working with Beam is how to approach debugging and how to debug basic functionality on your laptop. In this blog post, I am going to show 4 ways that can help you improve your debugging.

QUICK NOTE:

This blog gives a high level overview of how to debug data pipelines. For a deeper dive, you may want to check out this video which talks about unittests with Apache Beam and this video which walks you through the debugging process for a basic data pipeline.

1) Only run time-consuming unit tests if dependent libraries are installed

If you are using unittest, it is helpful to have a test that only runs if the correct libraries are installed. In the above Python example, I have a try block which looks for a class within a Google Cloud library. If the class isn’t found, the unit test is skipped, and a message is displayed that says ‘GCP dependencies are not installed.’

2) Use TestPipeline when running local unit tests

Apache Beam uses a Pipeline object in order to help construct a directed acyclic graph (DAG) of transformations. You could also use apache_beam.testing.TestPipeline so that you do less configuration when constructing basic tests.

Example of a directed acyclic graph (courtesy of https://en.wikipedia.org/wiki/Directed_acyclic_graph )

For 2 additional tips on how to debug data pipelines. Take a look at https://www.whiteowleducation.com/4-ways-to-effectively-debug-data-pipelines-in-apache-beam/