[SPARK-15822][SQL] Prevent byte array backed classes from referencing freed memory #13723
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Test build #60674 has finished for PR 13723 at commit
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lgtm. |
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LGTM, |
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…g freed memory ## What changes were proposed in this pull request? `UTF8String` and all `Unsafe*` classes are backed by either on-heap or off-heap byte arrays. The code generated version `SortMergeJoin` buffers the left hand side join keys during iteration. This was actually problematic in off-heap mode when one of the keys is a `UTF8String` (or any other 'Unsafe*` object) and the left hand side iterator was exhausted (and released its memory); the buffered keys would reference freed memory. This causes Seg-faults and all kinds of other undefined behavior when we would use one these buffered keys. This PR fixes this problem by creating copies of the buffered variables. I have added a general method to the `CodeGenerator` for this. I have checked all places in which this could happen, and only `SortMergeJoin` had this problem. This PR is largely based on the work of robbinspg and he should be credited for this. closes #13707 ## How was this patch tested? Manually tested on problematic workloads. Author: Pete Robbins <robbinspg@gmail.com> Author: Herman van Hovell <hvanhovell@databricks.com> Closes #13723 from hvanhovell/SPARK-15822-2. (cherry picked from commit 5ada606) Signed-off-by: Davies Liu <davies.liu@gmail.com>
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What changes were proposed in this pull request?
UTF8Stringand allUnsafe*classes are backed by either on-heap or off-heap byte arrays. The code generated versionSortMergeJoinbuffers the left hand side join keys during iteration. This was actually problematic in off-heap mode when one of the keys is aUTF8String(or any other 'Unsafe*` object) and the left hand side iterator was exhausted (and released its memory); the buffered keys would reference freed memory. This causes Seg-faults and all kinds of other undefined behavior when we would use one these buffered keys.This PR fixes this problem by creating copies of the buffered variables. I have added a general method to the
CodeGeneratorfor this. I have checked all places in which this could happen, and onlySortMergeJoinhad this problem.This PR is largely based on the work of @robbinspg and he should be credited for this.
closes #13707
How was this patch tested?
Manually tested on problematic workloads.