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https://issues.apache.org/jira/browse/GROOVY-12457?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18128375#comment-18128375
]
ASF GitHub Bot commented on GROOVY-12457:
-----------------------------------------
codecov-commenter commented on PR #2986:
URL: https://github.com/apache/groovy/pull/2986#issuecomment-6248259525
##
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Report
:x: Patch coverage is `85.85859%` with `14 lines` in your changes missing
coverage. Please review.
:white_check_mark: Project coverage is 72.4184%. Comparing base
([`d77e6df`](https://app.codecov.io/gh/apache/groovy/commit/d77e6df56a8d59ca30afbfa4c66afb9c685a22db?dropdown=coverage&el=desc&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache))
to head
([`c5a58cb`](https://app.codecov.io/gh/apache/groovy/commit/c5a58cbd220c9af08d8e20df50efd81dc5f2af1c?dropdown=coverage&el=desc&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache)).
| [Files with missing
lines](https://app.codecov.io/gh/apache/groovy/pull/2986?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache)
| Patch % | Lines |
|---|---|---|
|
[...s/groovy/runtime/ParallelCollectionExtensions.java](https://app.codecov.io/gh/apache/groovy/pull/2986?src=pr&el=tree&filepath=src%2Fmain%2Fjava%2Forg%2Fcodehaus%2Fgroovy%2Fruntime%2FParallelCollectionExtensions.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache#diff-c3JjL21haW4vamF2YS9vcmcvY29kZWhhdXMvZ3Jvb3Z5L3J1bnRpbWUvUGFyYWxsZWxDb2xsZWN0aW9uRXh0ZW5zaW9ucy5qYXZh)
| 85.8586% | [12 Missing and 2 partials :warning:
](https://app.codecov.io/gh/apache/groovy/pull/2986?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache)
|
<details><summary>Additional details and impacted files</summary>
[](https://app.codecov.io/gh/apache/groovy/pull/2986?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache)
```diff
@@ Coverage Diff @@
## master #2986 +/- ##
==================================================
+ Coverage 72.4166% 72.4184% +0.0018%
- Complexity 40606 40634 +28
==================================================
Files 1643 1643
Lines 142633 142711 +78
Branches 26788 26792 +4
==================================================
+ Hits 103290 103349 +59
- Misses 29850 29862 +12
- Partials 9493 9500 +7
```
| [Files with missing
lines](https://app.codecov.io/gh/apache/groovy/pull/2986?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache)
| Coverage Δ | |
|---|---|---|
|
[...s/groovy/runtime/ParallelCollectionExtensions.java](https://app.codecov.io/gh/apache/groovy/pull/2986?src=pr&el=tree&filepath=src%2Fmain%2Fjava%2Forg%2Fcodehaus%2Fgroovy%2Fruntime%2FParallelCollectionExtensions.java&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache#diff-c3JjL21haW4vamF2YS9vcmcvY29kZWhhdXMvZ3Jvb3Z5L3J1bnRpbWUvUGFyYWxsZWxDb2xsZWN0aW9uRXh0ZW5zaW9ucy5qYXZh)
| `86.2319% <85.8586%> (-3.7681%)` | :arrow_down: |
... and [12 files with indirect coverage
changes](https://app.codecov.io/gh/apache/groovy/pull/2986/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apache)
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</details>
> Blocking parallel-collection callbacks can fail to run a queued sibling task
> ----------------------------------------------------------------------------
>
> Key: GROOVY-12457
> URL: https://issues.apache.org/jira/browse/GROOVY-12457
> Project: Groovy
> Issue Type: Bug
> Reporter: Daniel Sun
> Priority: Major
>
> h2. Context
> {{{}eachParallel{}}}, {{{}collectParallel{}}}, and the other parallel
> collection methods run their callback on a {{{}ForkJoinPool{}}}: the pool
> bound by {{{}ParallelScope.withPool{}}}, or {{ForkJoinPool.commonPool()}}
> when no pool is bound. {{@Parallel}} {{for-in}} loops are rewritten to call
> {{{}eachParallel{}}}. The methods arrived with GROOVY-11952
> ([GEP-18|https://groovy.apache.org/wiki/GEP-18.html]).
> A pool of size {{n}} is the intended way to run {{n}} callbacks that block at
> the same time.
> h2. Problem
> This rendezvous fails intermittently, including when the pool size equals the
> number of parties:
> {code:groovy}
> import groovy.concurrent.ParallelScope
> import java.util.concurrent.CyclicBarrier
> import java.util.concurrent.TimeUnit
> int parties = 2
> ParallelScope.withPool(parties) { scope ->
> def barrier = new CyclicBarrier(parties)
> (1..parties).eachParallel {
> barrier.await(5, TimeUnit.SECONDS)
> }
> }
> {code}
> {{CyclicBarrier.await}} throws {{TimeoutException}} because the second
> element never starts. The failure is reported as a nested
> {{{}UndeclaredThrowableException{}}}:
> ||Layer||What the caller sees||
> |Closure|{{TimeoutException}} from {{CyclicBarrier.await}}|
> |{{Consumer}} proxy|{{{}UndeclaredThrowableException{}}}, because {{accept}}
> does not declare checked exceptions|
> |{{ForkJoinTask.getThrowableException}}|A second
> {{{}UndeclaredThrowableException{}}}, rebuilt on the joining thread|
> The same shape fails for {{@Parallel}} {{{}for (item in 1..n){}}}. It shows
> up more often once the pool's workers have already run and parked. A freshly
> created pool can fail as well.
> h2. Cause
> {{parallelStream()}} forks the sibling leaf onto the current worker's queue,
> then runs one leaf on that same worker. {{CyclicBarrier.await}} is not a
> {{{}ForkJoinPool.ManagedBlocker{}}}, so the pool does not release or replace
> the blocked worker. If the other worker has already scanned and parked, the
> fork signal is not always delivered again. The sibling stays on the queue
> until the barrier times out.
> Sizing the pool to exactly {{n}} threads does not close the race. The idle
> thread is there; it is parked.
> h2. Change
> The proposed change runs the user callback inside
> {{ForkJoinPool.managedBlock}} when the current worker still has queued tasks.
> That releases a parked worker, or creates a spare, before the callback can
> block. A leaf whose queue is empty is unchanged.
> * JDK 20 and later read {{{}ForkJoinWorkerThread.getQueuedTaskCount(){}}}.
> * JDK 17 does not have that method, so the check uses the pool-wide
> queued-task estimate.
> The wrapper covers every parallel-collection callback, including
> {{eachWithIndexParallel}} and the {{eachParallel}} call emitted for
> {{{}@Parallel{}}}.
> Compensation runs only when a sibling is already queued. A callback that
> blocks before any sibling has been forked can still stall, and so can a pool
> that refuses another thread. Work that spends most of its time waiting still
> fits {{Pool.io()}} or {{Pool.virtual()}} better than a fixed
> {{{}ForkJoinPool{}}}.
> h2. Tests
> * {{ParallelCollectionTest}} and {{ParallelAnnotationTest}} repeat the
> two-party barrier on one pool, so later rounds run against workers parked by
> the first round. The barrier must trip.
> * The thread-count assertion allows a spare ({{{}size() >= parties{}}}),
> because {{managedBlock}} may add one while a worker is blocked.
> * The full two test classes passed on JDK 25. The three barrier tests also
> passed on JDK 17, which exercises the queue-length fallback.
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