comphead commented on code in PR #4519: URL: https://github.com/apache/datafusion-comet/pull/4519#discussion_r3352901485
########## spark/src/main/scala/org/apache/comet/rules/RevertNativeForTransitionHeavyStages.scala: ########## @@ -0,0 +1,143 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +package org.apache.comet.rules + +import org.apache.spark.internal.Logging +import org.apache.spark.sql.SparkSession +import org.apache.spark.sql.catalyst.rules.Rule +import org.apache.spark.sql.comet.{CometColumnarToRowExec, CometExec, CometNativeColumnarToRowExec, CometSparkToColumnarExec} +import org.apache.spark.sql.execution.{ColumnarToRowExec, ColumnarToRowTransition, RowToColumnarExec, SparkPlan} +import org.apache.spark.sql.execution.adaptive.QueryStageExec +import org.apache.spark.sql.execution.exchange.{BroadcastExchangeLike, ShuffleExchangeLike} + +import org.apache.comet.CometConf + +/** + * Reverts a query stage to Spark row-based execution when it has too many columnar-to-row (C2R) + * transitions. Each C2R indicates Comet could not keep execution columnar and had to fall back. + * With columnar shuffle enabled, each C2R implies a corresponding R2C round-trip. + */ +case class RevertNativeForTransitionHeavyStages(session: SparkSession) + extends Rule[SparkPlan] + with Logging { + + private lazy val enabled = CometConf.COMET_EXEC_TRANSITION_REVERT_ENABLED.get() + private lazy val maxTransitions = CometConf.COMET_EXEC_TRANSITION_REVERT_MAX_TRANSITIONS.get() + + override def apply(plan: SparkPlan): SparkPlan = { + if (!enabled) return plan + + if (session.sessionState.conf.adaptiveExecutionEnabled) { + applyForAQE(plan) + } else { + applyForNonAQE(plan) + } + } + + private def applyForAQE(plan: SparkPlan): SparkPlan = { + plan match { + case _: BroadcastExchangeLike => plan + case exchange: ShuffleExchangeLike => + revertStageIfNeeded(exchange.child, exchange.supportsColumnar) + .map(reverted => exchange.withNewChildren(Seq(reverted))) + .getOrElse(plan) + case _ => + revertStageIfNeeded(plan, outputColumnar = false).getOrElse(plan) + } + } + + private def applyForNonAQE(plan: SparkPlan): SparkPlan = { + val withRevertedStages = plan.transformUp { case exchange: ShuffleExchangeLike => + revertStageIfNeeded(exchange.child, exchange.supportsColumnar) + .map(reverted => exchange.withNewChildren(Seq(reverted))) + .getOrElse(exchange) + } + revertStageIfNeeded(withRevertedStages, outputColumnar = false) + .getOrElse(withRevertedStages) + } + + /** + * Reverts the stage if C2R count exceeds threshold. Wraps in R2C if exchange needs columnar. + */ + private def revertStageIfNeeded( + stagePlan: SparkPlan, + outputColumnar: Boolean): Option[SparkPlan] = { + val transitionCount = countTransitions(stagePlan) + if (transitionCount <= maxTransitions) return None Review Comment: To make a user friendly response it would be better to use `withFallbackReason` instead of logging -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
