Fix flaky Prism Loopback test

[aIbrahiim]

Fixes: 36686
Successful run: https://github.com/aIbrahiim/beam/actions/runs/19733880762

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[gemini-code-assist]

Summary of Changes

Hello @aIbrahiim, 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 flakiness issue in the Prism Loopback test by refining the project's Gradle build configuration. The core change involves removing an unnecessary import statement from the settings.gradle.kts file, which was likely a source of instability or conflict within the build environment, thereby improving the reliability of the test suite.

Highlights

• Build Configuration Cleanup: An unused or potentially problematic import statement for com.gradle.enterprise.gradleplugin.internal.extension.BuildScanExtensionWithHiddenFeatures has been removed from settings.gradle.kts.
• Test Stability Improvement: This change is specifically aimed at fixing flakiness observed in the Prism Loopback test, suggesting the removed import was contributing to build or test instability.

Ignored Files

• Ignored by pattern: .github/workflows/** (1)
  • .github/workflows/beam_PreCommit_Java_PVR_Prism_Loopback.yml

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[github-actions]

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[shunping]

Thanks for fixing this @aIbrahiim !

While the panic of empty key looks noisy and problematic, I think it is actually not the true cause of the test failure. If you check one of successful workflow runs, you will also see those (e.g. https://github.com/apache/beam/actions/runs/19723639617/job/56510787320). The successful run in your description also has the panic message in the log after your fix (https://github.com/aIbrahiim/beam/actions/runs/19733880762)

On the other hand, the flakiness seems to be a combine test where an empty PCollection is used as the view.

[shunping]

Thanks for fixing this @aIbrahiim !

While the panic of empty key looks noisy and problematic, I think it is actually not the true cause of the test failure. If you check one of successful workflow runs, you will also see those (e.g. https://github.com/apache/beam/actions/runs/19723639617/job/56510787320).

On the other hand, the flakiness seems to be a combine test where an empty PCollection is used as the view.

Actually I overlooked this problem. Sorry about that.

Even though it is not causing the test to fail (only because it is not covered), it is a true issue that must be addressed.

I opened a separate bug to track that #36965.

[lostluck]

Please keep the comment unless there's a good reason to remove it. It indicates intent of the following code.

[shunping]

Unfortunately, KeyDec will always be nil in the current code because we override the coder of the pcollection. Specifically, we length-prefix the coder for the output pcollection of TestStream:

beam/sdks/go/pkg/beam/runners/prism/internal/handlerunner.go

Line 315 in e3afe62

newPcol.CoderId = cID

Therefore, the coder will be a lp coder and we won't get a key decoder in the following line.

beam/sdks/go/pkg/beam/runners/prism/internal/execute.go

Line 218 in e3afe62

if kcid, ok := extractKVCoderID(col.GetCoderId(), coders); ok {

[shunping]

I think one possible solution for this is not to LP the entire kv coder during preprocessing, but only the value coder part.

In this case, we will keep a KV coder for this pcollection, then a fix like the current one can pick up the key decoder.

WDYT @lostluck ?

[shunping]

As #36983 has been merged, this PR can be safely closed as well.

Thanks again for proposing the fix, @aIbrahiim!