maryannxue commented on a change in pull request #24706: [SPARK-23128][SQL] A new approach to do adaptive execution in Spark SQL URL: https://github.com/apache/spark/pull/24706#discussion_r288253415
########## File path: sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/AdaptiveSparkPlanExec.scala ########## @@ -0,0 +1,367 @@ +/* + * 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.spark.sql.execution.adaptive + +import java.util.concurrent.LinkedBlockingQueue + +import scala.collection.concurrent.TrieMap +import scala.collection.mutable +import scala.concurrent.{ExecutionContext, ExecutionContextExecutorService} + +import org.apache.spark.SparkException +import org.apache.spark.rdd.RDD +import org.apache.spark.sql.SparkSession +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.expressions.Attribute +import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, ReturnAnswer} +import org.apache.spark.sql.catalyst.rules.{Rule, RuleExecutor} +import org.apache.spark.sql.execution._ +import org.apache.spark.sql.execution.exchange._ +import org.apache.spark.sql.execution.ui.SparkListenerSQLAdaptiveExecutionUpdate +import org.apache.spark.sql.internal.SQLConf +import org.apache.spark.sql.types.StructType +import org.apache.spark.util.ThreadUtils + +/** + * A root node to execute the query plan adaptively. It splits the query plan into independent + * stages and executes them in order according to their dependencies. The query stage + * materializes its output at the end. When one stage completes, the data statistics of the + * materialized output will be used to optimize the remainder of the query. + * + * To create query stages, we traverse the query tree bottom up. When we hit an exchange node, + * and if all the child query stages of this exchange node are materialized, we create a new + * query stage for this exchange node. The new stage is then materialized asynchronously once it + * is created. + * + * When one query stage finishes materialization, the rest query is re-optimized and planned based + * on the latest statistics provided by all materialized stages. Then we traverse the query plan + * again and create more stages if possible. After all stages have been materialized, we execute + * the rest of the plan. + */ +case class AdaptiveSparkPlanExec( + initialPlan: SparkPlan, + session: SparkSession, + subqueryMap: Map[Long, ExecSubqueryExpression], + stageCache: TrieMap[StructType, mutable.Buffer[(Exchange, QueryStageExec)]]) + extends LeafExecNode { + + def executedPlan: SparkPlan = currentPhysicalPlan + + override def output: Seq[Attribute] = initialPlan.output + + override def doCanonicalize(): SparkPlan = initialPlan.canonicalized + + override def doExecute(): RDD[InternalRow] = { + val events = new LinkedBlockingQueue[StageMaterializationEvent]() + var result = createQueryStages(currentPhysicalPlan) + while(!result.allChildStagesMaterialized) { Review comment: This is just part of the return result from create stages, so should not be expensive at all? ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
