[Drain] TimerData causedByDrain field by stankiewicz · Pull Request #37009 · apache/beam

stankiewicz · 2025-12-05T14:58:03Z

This is PR is adding new field to TimerData. Noop for most of implementation apart from runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/WindmillTimerInternals.java that propagates draining information to TimerData.

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stankiewicz · 2025-12-05T14:58:15Z

R: @kennknowles

gemini-code-assist · 2025-12-05T14:58:31Z

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 introduces a significant enhancement to the Apache Beam TimerData structure by adding a causedByDrain boolean field. This new field is designed to provide crucial context, allowing the system to differentiate between timers that are fired as part of a normal pipeline execution and those specifically triggered due to a draining operation. While the TimerData definition is updated globally, the specific logic for propagating the draining status is primarily implemented within the Dataflow worker's WindmillTimerInternals, with other timer instantiations defaulting to false. This change lays the groundwork for more robust and nuanced handling of timers during pipeline draining scenarios.

Highlights

New Field in TimerData: A new boolean field, causedByDrain, has been added to the TimerData class. This field indicates whether a timer was triggered as a result of a draining operation.
Dataflow Worker Integration: The WindmillTimerInternals in the Dataflow worker (runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/WindmillTimerInternals.java) has been updated to propagate the actual draining status to the new causedByDrain field when creating TimerData instances.
Default Behavior for Existing Timers: For most other existing timer creation sites across the codebase, the causedByDrain field is explicitly set to false, ensuring backward compatibility and a clear default value where draining status is not yet relevant or propagated.

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github-actions · 2025-12-05T14:59:21Z

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control. If you'd like to restart, comment assign set of reviewers

stankiewicz · 2025-12-05T18:22:16Z

Run Java PreCommit

kennknowles

Readability nit: it is more readable to make a two-item enum than to use booleans. Like

enum CausedByDrain { CAUSED_BY_DRAIN, NORMAL }

stankiewicz · 2025-12-23T13:55:11Z

@kennknowles added enum. will make it green now.

…tures. mostly noop. move from boolean to CausedByDrain { CAUSED_BY_DRAIN, NORMAL } dsdas

damccorm · 2026-02-04T20:22:05Z

runners/core-java/src/main/java/org/apache/beam/runners/core/TimerInternals.java

        Instant outputTimestamp,
-        TimeDomain domain) {
+        TimeDomain domain,
+        CausedByDrain causedByDrain) {


Because of how this object was previously constructed, this broke: https://github.com/apache/beam/actions/runs/21685692093/job/62531968855

This is because previously, if you had 5 arguments, they resolved to this function, with ordered arguments:

String timerId, StateNamespace namespace, Instant timestamp, Instant outputTimestamp, TimeDomain domain

after this change, if you have 5 arguments they resolve to a function below with arguments:

StateNamespace namespace, Instant timestamp, Instant outputTimestamp, TimeDomain domain, CausedByDrain causedByDrain

This is just an internal change, but given how many callers there are, we may have been better off preserving the previous ordering guarantees.

#37505 should fix. I'm confused why this didn't fail checks on this pr... That seems like the real problem here

Oh I see, its because the checks ran a few months ago and probably the repo has shifted significantly

github-actions bot added runners dataflow core samza labels Dec 5, 2025

stankiewicz force-pushed the timerdata branch from 11de028 to af8adfd Compare December 5, 2025 15:29

github-actions bot added the direct label Dec 5, 2025

stankiewicz force-pushed the timerdata branch 3 times, most recently from 78e6732 to bb107cf Compare December 5, 2025 17:13

stankiewicz mentioned this pull request Dec 5, 2025

[Drain] OnTimer - propagate caused by drain bit up to DoFnRunner #37012

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3 tasks

stankiewicz force-pushed the timerdata branch 2 times, most recently from c137e5a to 86bb6b1 Compare December 5, 2025 17:21

stankiewicz force-pushed the timerdata branch 2 times, most recently from 665d958 to 25224c6 Compare December 5, 2025 21:08

kennknowles approved these changes Dec 8, 2025

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stankiewicz force-pushed the timerdata branch from 25224c6 to 40fec32 Compare December 23, 2025 13:54

[Drain] Propagate drain information to timerData and TImer data struc…

9a5de4f

…tures. mostly noop. move from boolean to CausedByDrain { CAUSED_BY_DRAIN, NORMAL } dsdas

stankiewicz force-pushed the timerdata branch from 40fec32 to 9a5de4f Compare December 23, 2025 14:11

stankiewicz requested a review from kennknowles December 29, 2025 09:35

kennknowles approved these changes Feb 4, 2026

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kennknowles merged commit 1c22136 into apache:master Feb 4, 2026
20 of 21 checks passed

damccorm reviewed Feb 4, 2026

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[Drain] TimerData causedByDrain field#37009

[Drain] TimerData causedByDrain field#37009
kennknowles merged 1 commit intoapache:masterfrom
stankiewicz:timerdata

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damccorm Feb 4, 2026 •

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stankiewicz commented Dec 5, 2025

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Summary of Changes

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