typelevel / typelevel/fs2

`TopicSuite` is flaking frequently

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#3,071 1 comment 0 reactions 0 assignees View on GitHub

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bug
Dominant language
Scala
Stars
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Forks
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Avg merge
2d 4h
Merged PRs (30d)
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Description

==> X fs2.concurrent.TopicSuite.unregister subscribers under concurrent load  0.035s munit.ComparisonFailException: /home/runner/work/fs2/fs2/core/shared/src/test/scala/fs2/concurrent/TopicSuite.scala:113
112:        .map { result =>
113:          assertEquals(result.toMap.size, subs / 2)
114:          assertEquals(result.toMap, expected)
values are not the same
=> Obtained
6
=> Diff (- obtained, + expected)
-6
+5

Contributor guide

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with core/shared/src/test/scala/fs2/concurrent/TopicSuite.scala at line 113 and run the TopicSuite repeatedly under concurrent load to reproduce the failure. Trace why unregister subscribers produces an obtained map size of 6 instead of the expected 5, and consider the issue done when the test is stable with the expected result.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
distributed-systems, testing-qa
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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