[KafkaIO] Exit the poll loop in ReadFromKafkaDoFn after consumerPollingTimeout has elapsed

[sjvanrossum]

ReadFromKafkaDoFn may keep running without yielding to the runner if records keeps arriving, because this loop can only be escaped when no records have arrived within consumerPollingTimeout or the restriction is truncated.

Exiting the loop after consumerPollingTimeout has elapsed prevents the SDF from running continuously without yielding to the runner.

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[gemini-code-assist]

Summary of Changes

Hello @sjvanrossum, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a potential starvation issue in the KafkaIO connector's ReadFromKafkaDoFn where the processElement method could continuously poll for records without yielding to the Beam runner. The changes ensure that the polling loop respects the consumerPollingTimeout, allowing the Splittable DoFn to periodically yield control, thereby improving the responsiveness and stability of Kafka-consuming Beam pipelines.

Highlights

• Prevent indefinite polling: The ReadFromKafkaDoFn's poll loop now exits after consumerPollingTimeout has elapsed, preventing it from running continuously without yielding to the runner, even when records are constantly arriving.
• Improved yielding behavior: By ensuring the poll loop terminates within the specified timeout, the SDF (Splittable DoFn) can yield control back to the Beam runner, improving overall pipeline stability and resource management.
• Explicit ProcessContinuation: The processElement method now explicitly returns ProcessContinuation.resume(), ensuring the runner is informed to continue processing the element.

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[sjvanrossum]

Summary of Changes

Hello @sjvanrossum, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a potential starvation issue in the KafkaIO connector's ReadFromKafkaDoFn where the processElement method could continuously poll for records without yielding to the Beam runner. The changes ensure that the polling loop respects the consumerPollingTimeout, allowing the Splittable DoFn to periodically yield control, thereby improving the responsiveness and stability of Kafka-consuming Beam pipelines.

Highlights

• Prevent indefinite polling: The ReadFromKafkaDoFn's poll loop now exits after consumerPollingTimeout has elapsed, preventing it from running continuously without yielding to the runner, even when records are constantly arriving.
• Improved yielding behavior: By ensuring the poll loop terminates within the specified timeout, the SDF (Splittable DoFn) can yield control back to the Beam runner, improving overall pipeline stability and resource management.
• Explicit ProcessContinuation: The processElement method now explicitly returns ProcessContinuation.resume(), ensuring the runner is informed to continue processing the element.

Using Gemini Code Assist

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

Good bot.

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[Abacn]

Thank you!

We probably need to add an item of existing issue to CHANGES.md as well as website for Beam 2.64.0-2.67.0. Merge this for now.