Adds triggerring configuration to KafkaIO eos.

[stankiewicz]

Adds triggerring configuration to KafkaIO eos sink. EOS sink is slow when sending transactions with single element, to speed up, it's needed to trigger together multiple messages.

Scope of the change:

• adds configuration (numElements, timeout)
• adds window definition

---

Thank you for your contribution! Follow this checklist to help us incorporate your contribution quickly and easily:

• Mention the appropriate issue in your description (for example: addresses #123), if applicable. This will automatically add a link to the pull request in the issue. If you would like the issue to automatically close on merging the pull request, comment fixes #<ISSUE NUMBER> instead.
• Update CHANGES.md with noteworthy changes.
• If this contribution is large, please file an Apache Individual Contributor License Agreement.

See the Contributor Guide for more tips on how to make review process smoother.

To check the build health, please visit https://github.com/apache/beam/blob/master/.test-infra/BUILD_STATUS.md

GitHub Actions Tests Status (on master branch)

See CI.md for more information about GitHub Actions CI or the workflows README to see a list of phrases to trigger workflows.

[gemini-code-assist]

Summary of Changes

Hello @stankiewicz, 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 enhances the KafkaIO Exactly-Once Semantics (EOS) sink by introducing configurable triggering mechanisms. The primary goal is to optimize performance by allowing the sink to batch multiple messages or wait for a specified duration before committing transactions, addressing the inefficiency of single-element transactions. This change provides users with greater control over the trade-off between latency and throughput for their Kafka writes.

Highlights

• Configurable EOS Triggering: Introduced new configuration options, numElements and timeout, to control the triggering of transactions in the KafkaIO Exactly-Once Semantics (EOS) sink. This allows users to batch multiple messages before committing, improving performance for scenarios where single-element transactions are slow.
• Windowing Logic Update: Modified the internal windowing and triggering mechanism within KafkaExactlyOnceSink to leverage the new numElements and timeout parameters. The triggering now uses AfterFirst of AfterPane.elementCountAtLeast or AfterProcessingTime.pastFirstElementInPane().plusDelayOf.
• API Extension: Extended the KafkaIO.Write and KafkaIO.WriteRecords classes with a new withEOSTriggerConfig method, providing a fluent API for users to specify their desired batching behavior for EOS sinks.

🧠 New Feature in Public Preview: You can now enable Memory to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

Changelog

• sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/KafkaExactlyOnceSink.java
  • Added imports for AfterFirst, AfterProcessingTime, and Duration.
  • Extracted numElements and timeout from the sink specification for use in windowing.
  • Updated the Window transformation's triggering logic to use Repeatedly.forever(AfterFirst.of(AfterPane.elementCountAtLeast(numElements), AfterProcessingTime.pastFirstElementInPane().plusDelayOf(timeout))) for both initial input and sequenced elements.
• sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/KafkaIO.java
  • Set default values for numElements (100) and timeout (1 second) in the WriteRecords builder when EOS is enabled.
  • Added abstract getter methods getNumElements() and getTimeout() to the WriteRecords class.
  • Added abstract builder methods setNumElements() and setTimeout() to WriteRecords.Builder.
  • Introduced a new public method withEOSTriggerConfig(int numElements, Duration timeout) to WriteRecords for configuring the EOS trigger.
  • Added a corresponding withEOSTriggerConfig(int numElements, Duration timeout) method to KafkaIO.Write for configuring the EOS trigger via the top-level API.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

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. ↩

[johnjcasey]

I would name these more narrowly. Theres lots of potential numElements and timeouts in the scope of KafkaIO

[scwhittle]

is this needed or is the the windowing inherited from above?

[stankiewicz]

It didn't work without repeating triggering definition

[scwhittle]

we discussed, it looks like this is because the continuation trigger changes it to aftercount(1)

can you add a comment here
// Reapply the windowing configuration as the continuation trigger doesn't maintain the desired batching.

[scwhittle]

this is going to break update compatability, I think that either:

1. have the defaults result in the same windowing
2. or add support for the compatabilityversion option to be used to ignore the options and use the old windowing

[stankiewicz]

Ack, will keep the default behaviour and introduce new triggering when options are set.

[github-actions]

Assigning reviewers:

R: @chamikaramj for label java.
R: @Dippatel98 for label kafka.

Note: If you would like to opt out of this review, comment assign to next reviewer.

Available commands:

• stop reviewer notifications - opt out of the automated review tooling
• remind me after tests pass - tag the comment author after tests pass
• waiting on author - shift the attention set back to the author (any comment or push by the author will return the attention set to the reviewers)

The PR bot will only process comments in the main thread (not review comments).

[scwhittle]

Would be good to double-check the update compatability by running it, I think that specifying the second windowing should be fine because it is equivalent to the continuation triggering.

[scwhittle]

we discussed, it looks like this is because the continuation trigger changes it to aftercount(1)

can you add a comment here
// Reapply the windowing configuration as the continuation trigger doesn't maintain the desired batching.