[GitHub] [spark] zhongyu09 commented on a change in pull request #31167: [SPARK-33933][SQL] Materialize BroadcastQueryStage first to avoid broadcast timeout in AQE

[GitBox <gi...@apache.org>]

zhongyu09 commented on a change in pull request #31167:
URL: https://github.com/apache/spark/pull/31167#discussion_r557002156



##########
File path: sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/AdaptiveSparkPlanExec.scala
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@@ -190,7 +191,36 @@ case class AdaptiveSparkPlanExec(
           executionId.foreach(onUpdatePlan(_, result.newStages.map(_.plan)))
 
           // Start materialization of all new stages and fail fast if any stages failed eagerly
-          result.newStages.foreach { stage =>
+
+          // SPARK-33933: we should materialize broadcast stages first and wait the
+          // materialization finish before materialize other stages, to avoid waiting
+          // for broadcast tasks to be scheduled and leading to broadcast timeout.
+          val broadcastMaterializationFutures = result.newStages
+            .filter(_.isInstanceOf[BroadcastQueryStageExec])
+            .map { stage =>
+            var future: Future[Any] = null
+            try {
+              future = stage.materialize()
+              future.onComplete { res =>
+                if (res.isSuccess) {
+                  events.offer(StageSuccess(stage, res.get))
+                } else {
+                  events.offer(StageFailure(stage, res.failed.get))
+                }
+              }(AdaptiveSparkPlanExec.executionContext)
+            } catch {
+              case e: Throwable =>
+                cleanUpAndThrowException(Seq(e), Some(stage.id))
+            }
+            future
+          }
+
+          // Wait for the materialization of all broadcast stages finish
+          broadcastMaterializationFutures.foreach(ThreadUtils.awaitReady(_, Duration.Inf))

Review comment:
       In deed, there will be a little waste of resources. This is the same behavior as non-AQE. Given the lightweight of broadcast, it should not cause too much time, few seconds in normal. I think that's acceptable.
   If not wait, there's still probability that situations in #30998 will occur and cause broadcast timeout.




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