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[SPARK-22848][SQL] Eliminate mutable state from Stack #20035

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[SPARK-22848][SQL] Eliminate mutable state from Stack #20035

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2b65856
initial commit
kiszk Dec 20, 2017
81306c4
eliminate mutable states
kiszk Dec 20, 2017
d31ccd7
revert change for codegen in Generator
kiszk Dec 20, 2017
f0163e7
revert change for rowData
kiszk Dec 20, 2017
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14 changes: 7 additions & 7 deletions sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/generators.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -199,8 +199,7 @@ case class Stack(children: Seq[Expression]) extends Generator {

override protected def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
// Rows - we write these into an array.
val rowData = ctx.addMutableState("InternalRow[]", "rows",
v => s"$v = new InternalRow[$numRows];")
val rowData = ctx.freshName("rowsStack")
val values = children.tail
val dataTypes = values.take(numFields).map(_.dataType)
val code = ctx.splitExpressionsWithCurrentInputs(Seq.tabulate(numRows) { row =>
Expand All @@ -214,11 +213,12 @@ case class Stack(children: Seq[Expression]) extends Generator {

// Create the collection.
val wrapperClass = classOf[mutable.WrappedArray[_]].getName
ctx.addMutableState(
s"$wrapperClass<InternalRow>",
ev.value,
v => s"$v = $wrapperClass$$.MODULE$$.make($rowData);", useFreshName = false)
ev.copy(code = code, isNull = "false")
ev.copy(code =
s"""
|InternalRow[] $rowData = new InternalRow[$numRows];
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@cloud-fan cloud-fan Dec 20, 2017

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this creates a large array every time, and I don't think we have data copy issues for generator expressions...

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@kiszk kiszk Dec 20, 2017

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I see. I did not imagine that numRows is large.
I will revert the code for rowData.

|$code
|$wrapperClass<InternalRow> ${ev.value} = $wrapperClass$$.MODULE$$.make($rowData);
""".stripMargin, isNull = "false")
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@kiszk kiszk Dec 20, 2017 •
edited
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This change does not use inline = true at ctx.addMutableState for correct code generation.

}
}

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