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[SPARK-14092] [SQL] move shouldStop() to end of while loop #11912

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[SPARK-14092] [SQL] move shouldStop() to end of while loop #11912

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move shouldStop() to end of while loop
Mar 23, 2016
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Mar 23, 2016
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8 changes: 5 additions & 3 deletions sql/core/src/main/scala/org/apache/spark/sql/execution/ExistingRDD.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -255,11 +255,12 @@ private[sql] case class DataSourceScan(
| $numOutputRows.add(numRows);
| }
|
| while (!shouldStop() && $idx < numRows) {
| // this loop is very perf sensitive and changes to it should be measured carefully
| while ($idx < numRows) {
| int $rowidx = $idx++;
| ${consume(ctx, columns1).trim}
| if (shouldStop()) return;
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@rxin rxin Mar 23, 2016

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Can we add some comment somewhere to explain why shouldStop needs to be here? It'd be great to reference the JIRA ticket.

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@davies davies Mar 23, 2016

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It's here in the beginning.

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@rxin rxin Mar 23, 2016

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where is it?

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@rxin rxin Mar 23, 2016

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btw i'm not sure but i suspect this has to do with loop unrolling. jit stops unrolling the loop when shouldStop is part of the terminal condition.

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@nongli nongli Mar 23, 2016

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Can we add a comment around line 248 saying this loop is very perf sensitive and changes to it should be measured carefully?

| }
| if (shouldStop()) return;
|
| if (!$input.hasNext()) {
| $batch = null;
Expand All @@ -280,14 +281,15 @@ private[sql] case class DataSourceScan(
s"""
| private void $scanRows(InternalRow $row) throws java.io.IOException {
| boolean firstRow = true;
| while (!shouldStop() && (firstRow || $input.hasNext())) {
| while (firstRow || $input.hasNext()) {
| if (firstRow) {
| firstRow = false;
| } else {
| $row = (InternalRow) $input.next();
| }
| $numOutputRows.add(1);
| ${consume(ctx, columns2, inputRow).trim}
| if (shouldStop()) return;
| }
| }""".stripMargin)

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8 changes: 5 additions & 3 deletions sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegen.scala
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Expand Up @@ -104,11 +104,12 @@ trait CodegenSupport extends SparkPlan {
* # call child.produce()
* initialized = true;
* }
* while (!shouldStop() && hashmap.hasNext()) {
* while (hashmap.hasNext()) {
* row = hashmap.next();
* # build the aggregation results
* # create variables for results
* # call consume(), which will call parent.doConsume()
* if (shouldStop()) return;
* }
*/
protected def doProduce(ctx: CodegenContext): String
Expand Down Expand Up @@ -252,9 +253,10 @@ case class InputAdapter(child: SparkPlan) extends UnaryNode with CodegenSupport
ctx.currentVars = null
val columns = exprs.map(_.gen(ctx))
s"""
| while (!shouldStop() && $input.hasNext()) {
| while ($input.hasNext()) {
| InternalRow $row = (InternalRow) $input.next();
| ${consume(ctx, columns, row).trim}
| if (shouldStop()) return;
| }
""".stripMargin
}
Expand Down Expand Up @@ -321,7 +323,7 @@ case class WholeStageCodegen(child: SparkPlan) extends UnaryNode with CodegenSup
/** Codegened pipeline for:
* ${toCommentSafeString(child.treeString.trim)}
*/
class GeneratedIterator extends org.apache.spark.sql.execution.BufferedRowIterator {
final class GeneratedIterator extends org.apache.spark.sql.execution.BufferedRowIterator {

private Object[] references;
${ctx.declareMutableStates()}
Expand Down
3 changes: 2 additions & 1 deletion sql/core/src/main/scala/org/apache/spark/sql/execution/basicOperators.scala
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Expand Up @@ -282,13 +282,14 @@ case class Range(
| }
| }
|
| while (!$overflow && $checkEnd && !shouldStop()) {
| while (!$overflow && $checkEnd) {
| long $value = $number;
| $number += ${step}L;
| if ($number < $value ^ ${step}L < 0) {
| $overflow = true;
| }
| ${consume(ctx, Seq(ev))}
| if (shouldStop()) return;
| }
""".stripMargin
}
Expand Down