attilapiros commented on a change in pull request #25299: [SPARK-27651][Core] Avoid the network when shuffle blocks are fetched from the same host URL: https://github.com/apache/spark/pull/25299#discussion_r347535427
########## File path: common/network-shuffle/src/main/java/org/apache/spark/network/shuffle/protocol/LocalDirsForExecutors.java ########## @@ -0,0 +1,117 @@ +/* + * 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.network.shuffle.protocol; + +import com.google.common.base.Objects; +import io.netty.buffer.ByteBuf; +import org.apache.spark.network.protocol.Encoders; + +import java.util.*; +import java.util.Map.Entry; + +// Needed by ScalaDoc. See SPARK-7726 + + +/** The reply to get local dirs giving back the dirs for each of the requested executors. */ +public class LocalDirsForExecutors extends BlockTransferMessage { + private final String[] execIds; + private final int[] numLocalDirsByExec; + private final String[] allLocalDirs; + + public LocalDirsForExecutors(Map<String, String[]> localDirsByExec) { + this.execIds = new String[localDirsByExec.size()]; + this.numLocalDirsByExec = new int[localDirsByExec.size()]; + ArrayList<String> localDirs = new ArrayList<>(); + int index = 0; + for (Entry<String, String[]> e: localDirsByExec.entrySet()) { + execIds[index] = e.getKey(); + numLocalDirsByExec[index] = e.getValue().length; + Collections.addAll(localDirs, e.getValue()); + index++; + } + this.allLocalDirs = localDirs.toArray(new String[0]); Review comment: I changed it locally then IntelliJ suggested to change it back to an empty array, so I read after a bit and they say calling it with empty array can be more effective: > Bottom line: toArray(new T[0]) seems faster, safer, and contractually cleaner, and therefore should be the default choice now. Future VM optimizations may close this performance gap for toArray(new T[size]), rendering the current "believed to be optimal" usages on par with an actually optimal one. Further improvements in toArray APIs would follow the same logic as toArray(new T[0]) — the collection itself should create the appropriate storage. https://shipilev.net/blog/2016/arrays-wisdom-ancients/ ---------------------------------------------------------------- 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]
