Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/15480#discussion_r89513885
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/GenerateOrdering.scala
---
@@ -118,7 +118,42 @@ object GenerateOrdering extends
CodeGenerator[Seq[SortOrder], Ordering[InternalR
}
"""
}.mkString("\n")
- comparisons
+
+ /*
+ * 40 = 7000 bytes / 170 (around 170 bytes per ordering comparison).
+ * The maximum byte code size to be compiled for HotSpot is 8000 bytes.
+ * We should keep less than 8000 bytes.
+ */
+ val numberOfComparisonsThreshold = 40
+
+ if (ordering.size <= numberOfComparisonsThreshold) {
+ comparisons(ordering)
+ } else {
+ val groupedOrderingItr =
ordering.grouped(numberOfComparisonsThreshold)
+ val funcNamePrefix = ctx.freshName("compare")
+ val funcNames = groupedOrderingItr.zipWithIndex.map { case
(orderingGroup, i) =>
+ val funcName = s"${funcNamePrefix}_$i"
+ val funcCode =
+ s"""
+ |private int $funcName(InternalRow a, InternalRow b) {
+ | InternalRow ${ctx.INPUT_ROW} = null; // Holds current row
being evaluated.
+ | ${comparisons(orderingGroup)}
+ | return 0;
--- End diff --
for performance concerns, we should avoid using member variables. If there
is no easy way to reuse `splitExpressions`, I'm ok with the current approach.
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