boy-uber commented on a change in pull request #25007: [SPARK-28209][CORE][SHUFFLE] Proposed new shuffle writer API URL: https://github.com/apache/spark/pull/25007#discussion_r308375857
########## File path: core/src/main/java/org/apache/spark/shuffle/api/ShuffleMapOutputWriter.java ########## @@ -0,0 +1,73 @@ +/* + * 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.shuffle.api; + +import java.io.IOException; + +import org.apache.spark.annotation.Private; +import org.apache.spark.shuffle.ShuffleWriteMetricsReporter; + +/** + * :: Private :: + * A top-level writer that returns child writers for persisting the output of a map task, + * and then commits all of the writes as one atomic operation. + * + * @since 3.0.0 + */ +@Private +public interface ShuffleMapOutputWriter { + + /** + * Creates a writer that can open an output stream to persist bytes targeted for a given reduce + * partition id. + * <p> + * The chunk corresponds to bytes in the given reduce partition. This will not be called twice + * for the same partition within any given map task. The partition identifier will be in the + * range of precisely 0 (inclusive) to numPartitions (exclusive), where numPartitions was + * provided upon the creation of this map output writer via + * {@link ShuffleWriteSupport#createMapOutputWriter( + * int, int, long, int, ShuffleWriteMetricsReporter)}. + * <p> + * Calls to this method will be invoked with monotonically increasing reducePartitionIds; each + * call to this method will be called with a reducePartitionId that is strictly greater than + * the reducePartitionIds given to any previous call to this method. This method is not + * guaranteed to be called for every partition id in the above described range. In particular, + * no guarantees are made as to whether or not this method will be called for empty partitions. + */ + ShufflePartitionWriter getPartitionWriter(int reducePartitionId) throws IOException; Review comment: Why "calls to this method will be invoked with monotonically increasing reducePartitionIds"? This may cause potential issues in future and cause burden on implementation. for example, if people want to implement multiple partition writers and write shuffle data in parallel. It cannot guarantee monotonically increasing reducePartitionIds. ---------------------------------------------------------------- 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: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
