parEvalMap resets stream cancellation
Open
Nobody has claimed this yet.
bug
- Dominant language
- Scala
- Stars
- 2.5k
- Forks
- 636
- Avg merge
- 2d 4h
- Merged PRs (30d)
- 7
Description
fs2 version 3.10.2
this codes prints Succeeded
Stream
.eval(IO.canceled)
.parEvalMap(2)(_ => IO.unit)
.onFinalizeCase(c => IO.delay(println(c)))
.compile.drain
while using evalMap instead, it is properly Canceled:
Stream
.eval(IO.canceled)
.evalMap(_ => IO.unit)
.onFinalizeCase(c => IO.delay(println(c)))
.compile.drain
expected behavior:
I would expect cancellation in both cases.
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
Start by running the supplied fs2 3.10.2 reproducer and compare parEvalMap with evalMap, focusing on how cancellation reaches onFinalizeCase. Trace the relevant stream operations and add regression coverage for the reported case. Done means the parEvalMap example reports Canceled consistently with evalMap.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- scala
- Domain
- stream-processing
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100