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Deflake TestVStreamsMetricsErrors.#18679

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arthurschreiber merged 1 commit intomainfrom
arthur/fix-flaky-test
Sep 23, 2025
Merged

Deflake TestVStreamsMetricsErrors.#18679
arthurschreiber merged 1 commit intomainfrom
arthur/fix-flaky-test

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@arthurschreiber arthurschreiber commented Sep 23, 2025 •
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Description

The TestVStreamsMetricsErrors unit test was flaky, and this PR fixes that flakiness.

The main reason for the flakiness was that there's an inherent race condition in the test case, as there is no fixed order in which VStream events are processed:

  • If the VStream processes the stream events from shard 20-40 first, and then the error from -20, the test would be successful.
  • If the VStream processes the stream error from shard -20 first, it might cancel the processing of events from shard 20-40, which would cause the test to deadlock (because it was waiting for events to be returned via the ch channel).

The tests are now updated to handle both of these cases correctly.

I'd like these changes to be backported as this test also existed on older versions.

Related Issue(s)

Fixes #18678.

Checklist

  • "Backport to:" labels have been added if this change should be back-ported to release branches
  • If this change is to be back-ported to previous releases, a justification is included in the PR description
  • Tests were added or are not required
  • Did the new or modified tests pass consistently locally and on CI?
  • Documentation was added or is not required

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AI Disclosure

@arthurschreiber
Deflake TestVStreamsMetricsErrors.
911d5b7 
Signed-off-by: Arthur Schreiber <arthur@planetscale.com>
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vitess-bot bot commented Sep 23, 2025

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

  • Ensure that the Pull Request has a descriptive title.
  • Ensure there is a link to an issue (except for internal cleanup and flaky test fixes), new features should have an RFC that documents use cases and test cases.

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@vitess-bot vitess-bot bot added NeedsBackportReason If backport labels have been applied to a PR, a justification is required NeedsDescriptionUpdate The description is not clear or comprehensive enough, and needs work NeedsIssue A linked issue is missing for this Pull Request NeedsWebsiteDocsUpdate What it says labels Sep 23, 2025
@github-actions github-actions bot added this to the v23.0.0 milestone Sep 23, 2025
@arthurschreiber arthurschreiber added Component: Build/CI Type: Testing Backport to: release-21.0 Backport to: release-22.0 Needs to be backport to release-22.0 and removed NeedsDescriptionUpdate The description is not clear or comprehensive enough, and needs work NeedsWebsiteDocsUpdate What it says NeedsIssue A linked issue is missing for this Pull Request NeedsBackportReason If backport labels have been applied to a PR, a justification is required labels Sep 23, 2025
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codecov bot commented Sep 23, 2025 •
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.53%. Comparing base (8236f03) to head (911d5b7).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files 
@@            Coverage Diff             @@
##             main   #18679      +/-   ##
==========================================
+ Coverage   67.52%   67.53%   +0.01%     
==========================================
  Files        1608     1608              
  Lines      263611   263611              
==========================================
+ Hits       177994   178039      +45     
+ Misses      85617    85572      -45

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

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@arthurschreiber arthurschreiber merged commit e5593a8 into main Sep 23, 2025
107 of 114 checks passed
@arthurschreiber arthurschreiber deleted the arthur/fix-flaky-test branch September 23, 2025 14:11
This was referenced Sep 23, 2025
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arthurschreiber added a commit that referenced this pull request Sep 23, 2025
@arthurschreiber
Deflake TestVStreamsMetricsErrors. (#18679)
ae66cb3 
Signed-off-by: Arthur Schreiber <arthur@planetscale.com>
@arthurschreiber arthurschreiber mentioned this pull request Sep 24, 2025
Merged
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nickvanw pushed a commit that referenced this pull request Mar 31, 2026
@arthurschreiber @nickvanw
Deflake TestVStreamsMetricsErrors. (#18679)
58c0ff4 
Signed-off-by: Arthur Schreiber <arthur@planetscale.com>
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Reviewers

@timvaillancourt timvaillancourt timvaillancourt approved these changes

@rohit-nayak-ps rohit-nayak-ps rohit-nayak-ps approved these changes

@mattlord mattlord Awaiting requested review from mattlord mattlord is a code owner

@shlomi-noach shlomi-noach Awaiting requested review from shlomi-noach shlomi-noach is a code owner

@notfelineit notfelineit Awaiting requested review from notfelineit

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Backport to: release-22.0 Needs to be backport to release-22.0 Component: Build/CI Type: Testing

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Flaky test: TestVStreamsMetricsErrors

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