[SPARK-53435][SQL] Fix race condition in CachedRDDBuilder #52174
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cloud-fan
approved these changes
Aug 30, 2025
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cc @yaooqinn |
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Can we add the error in pr desc？ |
I no longer have the full stacktrace. I put the code path in the PR desc where the NPE was throw. |
yaooqinn
approved these changes
Sep 1, 2025
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thanks, merging to master/4.0! |
cloud-fan
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Sep 1, 2025
### What changes were proposed in this pull request? There is race condition between `CachedRDDBuilder.cachedColumnBuffers` and `CachedRDDBuilder.clearCache`: when they interleave each other, `cachedColumnBuffers` might return a `nullptr`. This looks like a day-1 bug introduced from 20ca208#diff-4068fce361a50e3d32af2ba2d4231905f500e7b2da9f46d5ddd99b758c30fd43 ### Why are the changes needed? The race condition might lead to NPE from [here](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/QueryStageExec.scala#L303) which is basically a null `RDD` returned from `CachedRDDBuilder.cachedColumnBuffers` ### Does this PR introduce _any_ user-facing change? NO ### How was this patch tested? Theoretically this race condition might be triggered as long as cache materialization and unpersistence happen on different thread. But there is no reliable way to construct unit test. ### Was this patch authored or co-authored using generative AI tooling? NO Closes #52174 from liuzqt/SPARK-53435. Authored-by: ziqi liu <[email protected]> Signed-off-by: Wenchen Fan <[email protected]> (cherry picked from commit 871fe3d) Signed-off-by: Wenchen Fan <[email protected]>
liuzqt
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Sep 2, 2025
### What changes were proposed in this pull request? There is race condition between `CachedRDDBuilder.cachedColumnBuffers` and `CachedRDDBuilder.clearCache`: when they interleave each other, `cachedColumnBuffers` might return a `nullptr`. This looks like a day-1 bug introduced from apache@20ca208#diff-4068fce361a50e3d32af2ba2d4231905f500e7b2da9f46d5ddd99b758c30fd43 ### Why are the changes needed? The race condition might lead to NPE from [here](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/QueryStageExec.scala#L303) which is basically a null `RDD` returned from `CachedRDDBuilder.cachedColumnBuffers` ### Does this PR introduce _any_ user-facing change? NO ### How was this patch tested? Theoretically this race condition might be triggered as long as cache materialization and unpersistence happen on different thread. But there is no reliable way to construct unit test. ### Was this patch authored or co-authored using generative AI tooling? NO Closes apache#52174 from liuzqt/SPARK-53435. Authored-by: ziqi liu <[email protected]> Signed-off-by: Wenchen Fan <[email protected]>
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What changes were proposed in this pull request?
There is race condition between
CachedRDDBuilder.cachedColumnBuffersandCachedRDDBuilder.clearCache: when they interleave each other,cachedColumnBuffersmight return anullptr.This looks like a day-1 bug introduced from 20ca208#diff-4068fce361a50e3d32af2ba2d4231905f500e7b2da9f46d5ddd99b758c30fd43
Why are the changes needed?
The race condition might lead to NPE from here which is basically a null
RDDreturned fromCachedRDDBuilder.cachedColumnBuffersDoes this PR introduce any user-facing change?
NO
How was this patch tested?
Theoretically this race condition might be triggered as long as cache materialization and unpersistence happen on different thread. But there is no reliable way to construct unit test.
Was this patch authored or co-authored using generative AI tooling?
NO