Quelle CustomFJPoolTest.java Sprache: JAVA

/*
* Copyright (c) 2017, 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.  Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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
* @summary Tests stream execution in a custom ForkJoinPool
* @bug 8190974
* @run testng/othervm CustomFJPoolTest
* @run testng/othervm -Djava.util.concurrent.ForkJoinPool.common.parallelism=0 CustomFJPoolTest
*/

import org.testng.annotations.Test;

import java.util.Comparator;
import java.util.Spliterator;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Consumer;
import java.util.stream.IntStream;
import java.util.stream.StreamSupport;

import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertTrue;

@Test
public class CustomFJPoolTest {

    // A Spliterator that counts the number of spliterators created
    // including itself, thus the count starts at 1
    static class SplitCountingSpliterator<T> implements Spliterator<T> {
        final Spliterator<T> s;
        final AtomicInteger nsplits;

        // Top-level constructor
        public SplitCountingSpliterator(Spliterator<T> s) {
            this.s = s;
            nsplits = new AtomicInteger(1);
        }

        // Splitting constructor
        SplitCountingSpliterator(Spliterator<T> s, AtomicInteger nsplits) {
            this.s = s;
            this.nsplits = nsplits;
        }

        int splits() {
            return nsplits.get();
        }

        @Override

        public boolean tryAdvance(Consumer<? super T> action) {
            return s.tryAdvance(action);
        }

        @Override
        public void forEachRemaining(Consumer<? super T> action) {
            s.forEachRemaining(action);
        }

        @Override
        public Spliterator<T> trySplit() {
            var split = s.trySplit();
            if (split != null) {
                nsplits.incrementAndGet();
                return new SplitCountingSpliterator<>(split, nsplits);
            }
            else {
                return null;
            }
        }

        @Override
        public long estimateSize() {
            return s.estimateSize();
        }

        @Override
        public long getExactSizeIfKnown() {
            return s.getExactSizeIfKnown();
        }

        @Override
        public int characteristics() {
            return s.characteristics();
        }

        @Override
        public boolean hasCharacteristics(int characteristics) {
            return s.hasCharacteristics(characteristics);
        }

        @Override
        public Comparator<? super T> getComparator() {
            return s.getComparator();
        }
    }

    public void testCustomPools() throws Exception {
        int splitsForP1 = countSplits(new ForkJoinPool(1));
        int splitsForP2 = countSplits(new ForkJoinPool(2));
        assertEquals(splitsForP2, splitsForP1 * 2);

        int commonParallelism = ForkJoinPool.getCommonPoolParallelism();
        if (commonParallelism > 1 && commonParallelism < 128) {
            int splitsForPHalfC = countSplits(new ForkJoinPool(commonParallelism / 2));
            int splitsForPC = countSplits(ForkJoinPool.commonPool());

            assertTrue(splitsForPHalfC < splitsForPC);
            assertEquals(splitsForPC / splitsForPHalfC,
                         nearestPowerOfTwo(commonParallelism) / nearestPowerOfTwo(commonParallelism / 2));
        }
    }

    static int countSplits(ForkJoinPool fjp) throws Exception {
        // The number of splits will be equivalent to the number of leaf nodes
        // and will be a power of 2
        var fInteger = fjp.submit(() -> {
            var s = IntStream.range(0, 1024).boxed().parallel().spliterator();
            var cs = new SplitCountingSpliterator<>(s);
            StreamSupport.stream(cs, true).forEach(e -> {});
            return cs.splits();
        });
        return fInteger.get();
    }

    static int nearestPowerOfTwo(int i) {
        return (i & (i - 1)) == 0
               ? i
               : 1 << (32 - Integer.numberOfLeadingZeros(i));
    }
}

quality96%

¤ Dauer der Verarbeitung: 0.2 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.