[SPARK-26955][CORE] Align Spark's TimSort to jdk11 implementation #23858
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MaxGekk
changed the title
srowen
reviewed
Feb 21, 2019
| */ | ||
| private void mergeCollapse() { | ||
| while (stackSize > 1) { | ||
| int n = stackSize - 2; | ||
| if ( (n >= 1 && runLen[n-1] <= runLen[n] + runLen[n+1]) | ||
| || (n >= 2 && runLen[n-2] <= runLen[n] + runLen[n-1])) { | ||
| if (n > 0 && runLen[n-1] <= runLen[n] + runLen[n+1] || |
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Are you sure about removing the parentheses? that changes the semantics, I believe, to (((a and b) or c) and d) . What's the implementation you're copying here, just to be sure?
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Looks good. TIL that && has higher precedence that || so this doesn't change things. Actually the whole change on this line doesn't cause any actual change, which is good; aligning the implementation exactly is useful though.
srowen
approved these changes
Feb 21, 2019
felixcheung
approved these changes
Feb 21, 2019
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Test build #102582 has finished for PR 23858 at commit
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jenkins, retest this, please |
HyukjinKwon
approved these changes
Feb 22, 2019
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Test build #102603 has finished for PR 23858 at commit
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Merged to master |
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What changes were proposed in this pull request?
Spark's TimSort deviates from JDK 11 TimSort in a couple places:
stackLenwas increased in jdkmergeCollapse:n < 0In the PR, I propose to align Spark TimSort to jdk implementation.
How was this patch tested?
By existing test suites, in particular,
SorterSuite.