`groupWithin` prematurely closes resources
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Nobody has claimed this yet.
bug
- Dominant language
- Scala
- Stars
- 2.5k
- Forks
- 636
- Avg merge
- 2d 4h
- Merged PRs (30d)
- 7
Description
Code:
import scala.concurrent.duration._
import cats.effect.{IO, Resource}
import fs2.Stream
import cats.effect.unsafe.implicits.global
Stream.resource(
Resource.make(IO.println("start"))(_ => IO.println("stop"))
)
.flatMap(_ => Stream(1,2,3,4).covary[IO].metered(100.millis))
.take(2)
.evalTap(IO.println)
.groupWithin(2, 1.second)
.evalTap(IO.println)
.compile
.drain
.unsafeRunSync()
Result:
start
1
2
stop
Chunk(1, 2)
The resource is already closed before the stage after groupWithin gets to process the chunk. So this can leak a closed resource.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Run the Scala reproduction in the issue and inspect the groupWithin stream stage, focusing on resource finalization around the .take(2) and downstream .evalTap. Confirm that stop occurs before the grouped chunk is processed, then use the observed lifecycle behavior to define done: downstream processing must not encounter a prematurely closed resource.
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
- 38/100