bhabegger commented on code in PR #2679: URL: https://github.com/apache/jackrabbit-oak/pull/2679#discussion_r2698091205
########## oak-commons/src/main/java/org/apache/jackrabbit/oak/commons/internal/concurrent/ExecutorHelper.java: ########## @@ -0,0 +1,99 @@ +/* + * 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.jackrabbit.oak.commons.internal.concurrent; + +import org.apache.commons.lang3.concurrent.BasicThreadFactory; +import org.jetbrains.annotations.NotNull; + +import java.util.concurrent.ExecutorService; +import java.util.concurrent.LinkedBlockingQueue; +import java.util.concurrent.ThreadPoolExecutor; +import java.util.concurrent.TimeUnit; + +/** + * Helper class complementing JDK's @see java.util.concurrent.Executors class with additional ExecutionService creation + */ +public class ExecutorHelper { + + /** + * Create a ThreadPoolExecutor with an unbounded LinkedBlockingQueue as work queue. + * <br> + * NOTE: The maximum number of threads in each executor service, when using a LinkedBlockingQueue(), is corePoolSize. + * all other tasks are kept in the LinkedBlockingQueue, which is unbounded. + * <br> + * @see <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/concurrent/ThreadPoolExecutor.html";>ThreadPoolExecutor javadoc</a> + * <br> + * (Using a bounded queue, such as SynchronousQueue would result in RejectedExecutionHandler if the queue would reach its capacity). + * We want to keep things simple and don't want to use back pressure or other mechanisms. So in summary, corePoolSize threads are used, per service. + * @param poolSize The size of the thread pool + * @param namePattern The name pattern for the threads containing %d replaced by the thread number (calculated by NamedThreadFactory). + * @param handler An optional handler for uncaught exceptions + * @return A ThreadPoolExecutor + */ + public static ThreadPoolExecutor linkedQueueExecutor(int poolSize, @NotNull String namePattern, Thread.UncaughtExceptionHandler handler) { + return linkedQueueExecutor(poolSize, poolSize, namePattern, handler); + } + + private static ThreadPoolExecutor linkedQueueExecutor(int minSize, int maxSize, @NotNull String namePattern, Thread.UncaughtExceptionHandler handler) { + // Either minSize=0 and maxSize=1 (maxSize > 1 behaves as if maxSize were 1) + // or minSize=maxSize (maxSize <> minSize behaves as if minSize were maxSize) + var factory = BasicThreadFactory.builder() + .daemon(true) + .namingPattern(namePattern); + if(handler != null) { + factory.uncaughtExceptionHandler(handler); + } + return new ThreadPoolExecutor(minSize, maxSize, 60L, TimeUnit.SECONDS, + new LinkedBlockingQueue<>(), factory.build()); + } + + /** + * Create a ThreadPoolExecutor with an unbounded LinkedBlockingQueue as work queue which will start a single thread + * in presence of work and will shut down the thread after 60 seconds of inactivity. + * <br> + * NOTE: ThreadPoolExecutor with an (unbounded) LinkedBlockingQueue does not allow setting both corePoolSize and maximumPoolSize, + * and thus does not allow starting more than a single thread in combination with reduction to 0. + * @param namePattern The name pattern for the threads containing %d replaced by the thread number (calculated by NamedThreadFactory). + * @param handler An optional handler for uncaught exceptions + * @return A ThreadPoolExecutor which will activate a single thread on demand and shut it down after 60 seconds of inactivity. + */ + public static ThreadPoolExecutor onDemandSingleThreadLinkedQueueExecutor(@NotNull String namePattern, Thread.UncaughtExceptionHandler handler) { + var factory = BasicThreadFactory.builder() + .daemon(true) + .namingPattern(namePattern); + if(handler != null) { + factory.uncaughtExceptionHandler(handler); + } + return new ThreadPoolExecutor(0, 1, 60L, TimeUnit.SECONDS, + new LinkedBlockingQueue<>(), factory.build()); + } Review Comment: Exactly! Thanks. That's why I created the internal method in the first place. 😜 -- 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]
