typelevel / typelevel/fs2

`interruptWhen` and friends shouldn't cancel downstream processing

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#3,202 7 comments 2 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

Stream(1,2).covary[IO].interruptAfter(200.millis).evalMap( i =>
  IO.println(i).delayBy(300.millis).onCancel(IO.println("CANCELED"))
).compile.drain.unsafeRunSync()

This program prints CANCELED even though this is happening downstream from interruptAfter.
Only canceling upstream would give more control to the clients of this stream.

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Research direction

Start by reproducing the Scala example with interruptAfter, evalMap, and the delayed onCancel handler, then inspect the cancellation behavior of interruptWhen and related operators. Done means interrupting the stream cancels upstream processing without triggering cancellation in downstream processing.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
stream-processing
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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