[CELEBORN #2250] Fix lock contention in ReducePartitionCommitHandler.finishMapperAttempt via fine-grained locks #3586
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Pull request overview
This pull request addresses lock contention issues in ReducePartitionCommitHandler.finishMapperAttempt by introducing fine-grained per-shuffle locks. The change replaces synchronization on the global shuffleMapperAttempts object with per-shuffle lock objects stored in a new shuffleIdLocks ConcurrentHashMap.
Changes:
- Added
shuffleIdLocksConcurrentHashMap to store per-shuffle lock objects - Updated
finishMapperAttemptto acquire per-shuffle locks instead of global lock - Updated
initMapperAttemptsto acquire per-shuffle locks instead of global lock
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RexXiong
reviewed
Jan 27, 2026
| private val shuffleMapperAttempts = JavaUtils.newConcurrentHashMap[Int, Array[Int]]() | ||
| // TODO: Move this to native Int -> Int Map | ||
| private val shuffleToCompletedMappers = JavaUtils.newConcurrentHashMap[Int, Int]() | ||
| private val shuffleIdLocks = JavaUtils.newConcurrentHashMap[Int, Object]() |
Contributor
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Better remove the lock object when the shuffle expired.
…ndler.finishMapperAttempt via fine-grained locks
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What changes were proposed in this pull request?
Add
shuffleIdLocks(fine-grained locks per shuffleId), replace globalshuffleMapperAttemptslock ininitMapperAttemptsandfinishMapperAttempt.Why are the changes needed?
High concurrency causes lock contention on
shuffleMapperAttemptsinfinishMapperAttempt, leading to abnormally long shuffle write time for small queries in Kyuubi Shared Mode. Fine-grained locks eliminate cross-shuffle blocking and improve concurrency.Does this PR resolve a correctness bug?
No.
Does this PR introduce any user-facing change?
No.
How was this patch tested?
CI.