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Java example source code file (MultithreadedInitializationTest.java)

This example Java source code file (MultithreadedInitializationTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

after, arraylist, atomiclong, before, brokenbarrierexception, cyclicbarrier, event_count, interruptedexception, line_sep, loggeraccessingthread, multithreadedinitializationtest, stringprintstream, thread_count, threading, threads, util

The MultithreadedInitializationTest.java Java example source code

/**
 * Copyright (c) 2004-2016 QOS.ch
 * All rights reserved.
 *
 * Permission is hereby granted, free  of charge, to any person obtaining
 * a  copy  of this  software  and  associated  documentation files  (the
 * "Software"), to  deal in  the Software without  restriction, including
 * without limitation  the rights to  use, copy, modify,  merge, publish,
 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
 * permit persons to whom the Software  is furnished to do so, subject to
 * the following conditions:
 *
 * The  above  copyright  notice  and  this permission  notice  shall  be
 * included in all copies or substantial portions of the Software.
 *
 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */
package org.slf4j.impl;

import static org.junit.Assert.assertEquals;

import java.io.PrintStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.atomic.AtomicLong;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.LoggerFactoryFriend;

public class MultithreadedInitializationTest {

    final static int THREAD_COUNT = 4 + Runtime.getRuntime().availableProcessors() * 2;

    private static AtomicLong EVENT_COUNT = new AtomicLong(0);

    final CyclicBarrier barrier = new CyclicBarrier(THREAD_COUNT + 1);

    int diff = new Random().nextInt(10000);
    String loggerName = "org.slf4j.impl.MultithreadedInitializationTest";
    private final PrintStream oldErr = System.err;
    StringPrintStream sps = new StringPrintStream(oldErr);

    @Before
    public void setup() {
        LoggerFactoryFriend.reset();
        System.setErr(sps);
    }

    @After
    public void tearDown() throws Exception {
        LoggerFactoryFriend.reset();
        System.setErr(oldErr);
    }

    @Test
    public void multiThreadedInitialization() throws InterruptedException, BrokenBarrierException {
        System.out.println("THREAD_COUNT=" + THREAD_COUNT);
        LoggerAccessingThread[] accessors = harness();

        for (LoggerAccessingThread accessor : accessors) {
            EVENT_COUNT.getAndIncrement();
            accessor.logger.info("post harness");
        }

        Logger logger = LoggerFactory.getLogger(loggerName + ".slowInitialization-" + diff);
        logger.info("hello");
        EVENT_COUNT.getAndIncrement();

        assertEquals(0, sps.stringList.size());
    }

    private static LoggerAccessingThread[] harness() throws InterruptedException, BrokenBarrierException {
        LoggerAccessingThread[] threads = new LoggerAccessingThread[THREAD_COUNT];
        final CyclicBarrier barrier = new CyclicBarrier(THREAD_COUNT + 1);
        for (int i = 0; i < THREAD_COUNT; i++) {
            threads[i] = new LoggerAccessingThread(barrier, i);
            threads[i].start();
        }

        barrier.await();
        for (int i = 0; i < THREAD_COUNT; i++) {
            threads[i].join();
        }
        return threads;
    }

    static class LoggerAccessingThread extends Thread {
        final CyclicBarrier barrier;
        Logger logger;
        int count;

        LoggerAccessingThread(CyclicBarrier barrier, int count) {
            this.barrier = barrier;
            this.count = count;
        }

        public void run() {
            try {
                barrier.await();
            } catch (Exception e) {
                e.printStackTrace();
            }
            logger = LoggerFactory.getLogger(this.getClass().getName() + "-" + count);
            logger.info("in run method");
            EVENT_COUNT.getAndIncrement();
        }
    };

    public static class StringPrintStream extends PrintStream {

        public static final String LINE_SEP = System.getProperty("line.separator");
        PrintStream other;
        List<String> stringList = new ArrayList();

        public StringPrintStream(PrintStream ps) {
            super(ps);
            other = ps;
        }

        public void print(String s) {
            other.print(s);
            stringList.add(s);
        }

        public void println(String s) {
            other.println(s);
            stringList.add(s);
        }

        public void println(Object o) {
            other.println(o);
            stringList.add(o.toString());
        }
    };

}

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