cloud-fan commented on a change in pull request #26516: [SPARK-29893] improve
the local shuffle reader performance by changing the reading task number from 1
to multi.
URL: https://github.com/apache/spark/pull/26516#discussion_r347761879
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/OptimizeLocalShuffleReader.scala
##########
@@ -27,78 +27,90 @@ import
org.apache.spark.sql.execution.exchange.{EnsureRequirements, ShuffleExcha
import org.apache.spark.sql.execution.joins.{BroadcastHashJoinExec, BuildLeft,
BuildRight, BuildSide}
import org.apache.spark.sql.internal.SQLConf
+
object BroadcastJoinWithShuffleLeft {
- def unapply(plan: SparkPlan): Option[(QueryStageExec, BuildSide)] = plan
match {
- case join: BroadcastHashJoinExec if
ShuffleQueryStageExec.isShuffleQueryStageExec(join.left) =>
- Some((join.left.asInstanceOf[QueryStageExec], join.buildSide))
+ def unapply(plan: SparkPlan): Option[(SparkPlan, BuildSide)] = plan match {
+ case join: BroadcastHashJoinExec if OptimizeLocalShuffleReader.
+ canUseLocalShuffleReader(join.left) =>
+ Some((join.left, join.buildSide))
case _ => None
}
}
object BroadcastJoinWithShuffleRight {
- def unapply(plan: SparkPlan): Option[(QueryStageExec, BuildSide)] = plan
match {
- case join: BroadcastHashJoinExec if
ShuffleQueryStageExec.isShuffleQueryStageExec(join.right) =>
- Some((join.right.asInstanceOf[QueryStageExec], join.buildSide))
+ def unapply(plan: SparkPlan): Option[(SparkPlan, BuildSide)] = plan match {
+ case join: BroadcastHashJoinExec if OptimizeLocalShuffleReader.
+ canUseLocalShuffleReader(join.right) =>
+ Some((join.right, join.buildSide))
case _ => None
}
}
/**
- * A rule to optimize the shuffle reader to local reader as far as possible
- * when converting the 'SortMergeJoinExec' to 'BroadcastHashJoinExec' in
runtime.
- *
- * This rule can be divided into two steps:
- * Step1: Add the local reader in probe side and then check whether additional
- * shuffle introduced. If introduced, we will revert all the local
- * reader in probe side.
- * Step2: Add the local reader in build side and will not check whether
- * additional shuffle introduced. Because the build side will not
introduce
- * additional shuffle.
+ * A rule to optimize the shuffle reader to local reader iff no additional
shuffles
+ * will be introduced:
+ * 1. if the input plan is a shuffle, add local reader directly as we can
never introduce
+ * extra shuffles in this case.
+ * 2. otherwise, add local reader to the probe side of broadcast hash join and
+ * then run `EnsureRequirements` to check whether additional shuffle
introduced.
+ * If introduced, we will revert all the local readers.
*/
case class OptimizeLocalShuffleReader(conf: SQLConf) extends Rule[SparkPlan] {
- override def apply(plan: SparkPlan): SparkPlan = {
- if (!conf.getConf(SQLConf.OPTIMIZE_LOCAL_SHUFFLE_READER_ENABLED)) {
- return plan
- }
- // Add local reader in probe side.
- val withProbeSideLocalReader = plan.transformDown {
+ def withProbeSideLocalReader(plan: SparkPlan): SparkPlan = {
+ plan.transformDown {
case join @ BroadcastJoinWithShuffleLeft(shuffleStage, BuildRight) =>
- val localReader = LocalShuffleReaderExec(shuffleStage)
+ val localReader = withLocalReader(shuffleStage)
join.asInstanceOf[BroadcastHashJoinExec].copy(left = localReader)
case join @ BroadcastJoinWithShuffleRight(shuffleStage, BuildLeft) =>
- val localReader = LocalShuffleReaderExec(shuffleStage)
+ val localReader = withLocalReader(shuffleStage)
join.asInstanceOf[BroadcastHashJoinExec].copy(right = localReader)
}
+ }
+
+ def withLocalReader(plan: SparkPlan): LocalShuffleReaderExec = {
Review comment:
nit: `createLocalReader`
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