[GitHub] carsonwang commented on a change in pull request #20303: [SPARK-23128][SQL] A new approach to do adaptive execution in Spark SQL

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carsonwang commented on a change in pull request #20303: [SPARK-23128][SQL] A new approach to do adaptive execution in Spark SQL
URL: https://github.com/apache/spark/pull/20303#discussion_r252951765
 
 

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 File path: sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/QueryStageTrigger.scala
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+/*
+ * 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 scala.collection.mutable.{HashMap, HashSet, ListBuffer}
+import scala.concurrent.{ExecutionContext, ExecutionContextExecutorService, Future}
+
+import org.apache.spark.sql.SparkSession
+import org.apache.spark.sql.execution.SparkPlan
+import org.apache.spark.util.{EventLoop, ThreadUtils}
+
+/**
+ * This class triggers [[QueryStage]] bottom-up, apply planner rules for query stages and
+ * materialize them. It triggers as many query stages as possible at the same time, and triggers
+ * the parent query stage when all its child stages are materialized.
+ */
+class QueryStageTrigger(session: SparkSession, callback: QueryStageTriggerCallback)
+  extends EventLoop[QueryStageTriggerEvent]("QueryStageTrigger") {
+
+  private val stageToParentStages = HashMap.empty[Int, ListBuffer[QueryStage]]
+
+  private val idToUpdatedStage = HashMap.empty[Int, QueryStage]
+
+  private val stageToNumPendingChildStages = HashMap.empty[Int, Int]
+
+  private val submittedStages = HashSet.empty[Int]
+
+  private val readyStages = HashSet.empty[Int]
+
+  private val planner = new QueryStagePlanner(session.sessionState.conf)
+
+  def trigger(stage: QueryStage): Unit = {
+    post(SubmitStage(stage))
+  }
+
+  private implicit def executionContext: ExecutionContextExecutorService = {
+    QueryStageTrigger.executionContext
+  }
+
+  override protected def onReceive(event: QueryStageTriggerEvent): Unit = event match {
+    case SubmitStage(stage) =>
+      // We may submit a query stage multiple times, because of stage reuse. Here we avoid
+      // re-submitting a query stage.
+      if (!submittedStages.contains(stage.id)) {
 
 Review comment:
   @JkSelf , in the new code, only one `MaterializeStage` message will be sent for a single query stage. can you please take a look and feedback if you still see an issue?

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