concurrent/ExecutorCompletionService/ExecutorCompletionServiceLoops.java

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
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 */

/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

/*
 * @test
 * @bug 4965960
 * @compile -source 1.5 ExecutorCompletionServiceLoops.java
 * @run main/timeout=3600 ExecutorCompletionServiceLoops
 * @summary  Exercise ExecutorCompletionServiceLoops
 */

import java.util.concurrent.*;

public class ExecutorCompletionServiceLoops {
    static final int POOLSIZE =      100;
    static final ExecutorService pool =
        Executors.newFixedThreadPool(POOLSIZE);
    static final ExecutorCompletionService<Integer> ecs =
        new ExecutorCompletionService<Integer>(pool);
    static boolean print = false;

    public static void main(String[] args) throws Exception {
        int max = 8;
        int base = 10000;

        if (args.length > 0)
            max = Integer.parseInt(args[0]);

        System.out.println("Warmup...");
        oneTest( base );
        Thread.sleep(100);
        print = true;

        for (int i = 1; i <= max; i += (i+1) >>> 1) {
            System.out.print("n: " + i * base);
            oneTest(i * base );
            Thread.sleep(100);
        }
        pool.shutdown();
        if (! pool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS))
            throw new Error();
   }

    static class Task implements Callable<Integer> {
        public Integer call() {
            int s = 0;
            int l = System.identityHashCode(this);
            for (int i = 0; i < 5; ++i) {
                l = LoopHelpers.compute2(l);
                s += LoopHelpers.compute1(l);
            }
            return new Integer(s);
        }
    }

    static class Producer implements Runnable {
        final ExecutorCompletionService cs;
        final int iters;
        Producer(ExecutorCompletionService ecs, int i) {
            cs = ecs;
            iters = i;
        }
        public void run() {
            for (int i = 0; i < iters; ++i)
                ecs.submit(new Task());
        }
    }

    static void oneTest(int iters) throws Exception {
        long startTime = System.nanoTime();
        new Thread(new Producer(ecs, iters)).start();

        int r = 0;
        for (int i = 0; i < iters; ++i)
            r += ecs.take().get().intValue();

        long elapsed = System.nanoTime() - startTime;
        long tpi = elapsed/ iters;

        if (print)
            System.out.println("\t: " + LoopHelpers.rightJustify(tpi) + " ns per task");

        if (r == 0) // avoid overoptimization
            System.out.println("useless result: " + r);


    }

}