viirya commented on code in PR #6883: URL: https://github.com/apache/datafusion-comet/pull/6883#discussion_r4266389002
########## spark-local/src/main/scala/org/apache/comet/local/CometLocalResultExec.scala: ########## @@ -0,0 +1,122 @@ +/* + * 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.local + +import java.util.concurrent.ConcurrentHashMap +import java.util.concurrent.atomic.AtomicLong + +import scala.collection.mutable.ArrayBuffer + +import org.apache.spark.SparkException +import org.apache.spark.rdd.RDD +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.expressions.{Attribute, SortOrder, UnsafeRow} +import org.apache.spark.sql.catalyst.plans.physical.Partitioning +import org.apache.spark.sql.execution.{SparkPlan, UnaryExecNode} + +/** + * Row result boundary of a local query. Spark's collect encodes and compresses every row of a + * result partition in its task, then decodes them on the driver. A local query has one result + * partition, so that work would run on a single thread. Admission requires an in-process local + * master, so collect and take still run one Spark task (keeping cancellation, job groups and SQL + * metrics) but hand copied rows to the driver in this JVM. + */ +case class CometLocalResultExec(child: SparkPlan) extends UnaryExecNode { Review Comment: Agreed, a single result partition defeats `executeToIterator`, which fetches one partition at a time to bound what the driver holds. Rather than a bounded handoff from a task that keeps running behind the iterator, which would also need cancellation when the iterator is abandoned, `CometLocalResultExec.executeToIterator` now runs the admitted native block as ordinary Comet execution, one Spark task per partition (89f4adae9). `toLocalIterator` and the Thrift server's incremental collect then behave as without local execution, including how `spark.driver.maxResultSize` applies, at the cost of local execution's speedup for these iterator actions. A test checks that the iterator runs one job per partition and matches Spark. PySpark's `toLocalIterator` goes through `javaToPython` and the result RDD instead, so it still receives the whole result as one partition. The docs now list that as a limitation; addressing it would need the local result RDD to expose more than one partition. -- 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]
