test/java/util/concurrent/ThreadPoolExecutor/TimeOutShrink.java

/*
 * Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
 * 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.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 6458662
 * @summary poolSize might shrink below corePoolSize after timeout
 * @author Martin Buchholz
 */

import java.util.*;
import java.util.concurrent.*;

public class TimeOutShrink {
    static void checkPoolSizes(ThreadPoolExecutor pool,
                               int size, int core, int max) {
        equal(pool.getPoolSize(), size);
        equal(pool.getCorePoolSize(), core);
        equal(pool.getMaximumPoolSize(), max);
    }

    private static void realMain(String[] args) throws Throwable {
        final int n = 4;
        final CyclicBarrier barrier = new CyclicBarrier(2*n+1);
        final ThreadPoolExecutor pool
            = new ThreadPoolExecutor(n, 2*n, 1L, TimeUnit.SECONDS,
                                     new SynchronousQueue<Runnable>());
        final Runnable r = new Runnable() { public void run() {
            try {
                barrier.await();
                barrier.await();
            } catch (Throwable t) { unexpected(t); }}};

        for (int i = 0; i < 2*n; i++)
            pool.execute(r);
        barrier.await();
        checkPoolSizes(pool, 2*n, n, 2*n);
        barrier.await();
        while (pool.getPoolSize() > n)
            Thread.sleep(100);
        Thread.sleep(100);
        checkPoolSizes(pool, n, n, 2*n);
        pool.shutdown();
        pool.awaitTermination(Long.MAX_VALUE, TimeUnit.SECONDS);
    }

    //--------------------- Infrastructure ---------------------------
    static volatile int passed = 0, failed = 0;
    static void pass() {passed++;}
    static void fail() {failed++; Thread.dumpStack();}
    static void fail(String msg) {System.out.println(msg); fail();}
    static void unexpected(Throwable t) {failed++; t.printStackTrace();}
    static void check(boolean cond) {if (cond) pass(); else fail();}
    static void equal(Object x, Object y) {
        if (x == null ? y == null : x.equals(y)) pass();
        else fail(x + " not equal to " + y);}
    public static void main(String[] args) throws Throwable {
        try {realMain(args);} catch (Throwable t) {unexpected(t);}
        System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
        if (failed > 0) throw new AssertionError("Some tests failed");}
}