50467c9e76
* Moves visitor pattern to java 11 * Moves value-object pattern to java 11 * Moves unit-of-work pattern to java 11 * Moves typeobjectpattern pattern to java 11 * Moves twin pattern to java 11 * Moves trampoline pattern to java 11 * Moves tolerant-reader pattern to java 11 * Moves tls pattern to java 11 * Moves throttling pattern to java 11 * Moves thread-pool pattern to java 11 * Moves template-method pattern to java 11
94 lines
3.7 KiB
Java
94 lines
3.7 KiB
Java
/*
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* The MIT License
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* Copyright © 2014-2019 Ilkka Seppälä
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package com.iluwatar.threadpool;
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import java.util.List;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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/**
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* Thread Pool pattern is where a number of threads are created to perform a number of tasks, which
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* are usually organized in a queue. The results from the tasks being executed might also be placed
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* in a queue, or the tasks might return no result. Typically, there are many more tasks than
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* threads. As soon as a thread completes its task, it will request the next task from the queue
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* until all tasks have been completed. The thread can then terminate, or sleep until there are new
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* tasks available.
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*
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* <p>In this example we create a list of tasks presenting work to be done. Each task is then
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* wrapped into a {@link Worker} object that implements {@link Runnable}. We create an {@link
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* ExecutorService} with fixed number of threads (Thread Pool) and use them to execute the {@link
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* Worker}s.
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*/
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public class App {
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private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
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/**
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* Program entry point.
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*
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* @param args command line args
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*/
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public static void main(String[] args) {
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LOGGER.info("Program started");
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// Create a list of tasks to be executed
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var tasks = List.of(
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new PotatoPeelingTask(3),
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new PotatoPeelingTask(6),
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new CoffeeMakingTask(2),
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new CoffeeMakingTask(6),
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new PotatoPeelingTask(4),
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new CoffeeMakingTask(2),
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new PotatoPeelingTask(4),
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new CoffeeMakingTask(9),
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new PotatoPeelingTask(3),
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new CoffeeMakingTask(2),
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new PotatoPeelingTask(4),
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new CoffeeMakingTask(2),
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new CoffeeMakingTask(7),
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new PotatoPeelingTask(4),
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new PotatoPeelingTask(5));
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// Creates a thread pool that reuses a fixed number of threads operating off a shared
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// unbounded queue. At any point, at most nThreads threads will be active processing
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// tasks. If additional tasks are submitted when all threads are active, they will wait
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// in the queue until a thread is available.
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var executor = Executors.newFixedThreadPool(3);
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// Allocate new worker for each task
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// The worker is executed when a thread becomes
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// available in the thread pool
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tasks.stream().map(Worker::new).forEach(executor::execute);
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// All tasks were executed, now shutdown
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executor.shutdown();
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while (!executor.isTerminated()) {
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Thread.yield();
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}
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LOGGER.info("Program finished");
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}
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}
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