russell@unturf.com
0a580b313d
Authors: russell@unturf.com · brackishbert@gmail.com · foxhop.net · TimeHexOn.com Patches, unit tests, benchmarks, whitepaper, and outreach briefs. Public domain — no copyright claimed. Use freely.
110 lines
4 KiB
Java
110 lines
4 KiB
Java
/*
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* Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* @test
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* @bug 8351230
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* @summary Test that List's new SequencedCollection methods are properly
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* synchronized on a synchronized list.
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* @library /test/lib
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* @build jdk.test.lib.Utils
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* @run main SyncListBash f
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* @run main SyncListBash r
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*/
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import java.util.*;
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import java.util.concurrent.*;
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import java.util.stream.*;
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import jdk.test.lib.Utils;
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public class SyncListBash {
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static final int LOOP_COUNT = 1000;
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static final int NUM_WORKERS = 4;
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static List<Integer> list;
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/**
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* Test for race conditions with synchronized lists. Several worker threads
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* add and remove elements from the front of the list, while the main thread
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* gets the last element. The last element should never change. However, if
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* the list isn't properly synchronized, getLast() might return the wrong
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* element or throw IndexOutOfBoundsException.
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*
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* On an unsynchronized list, this fails 200-500 out of 1000 times, so this
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* seems like a fairly reliable way to test for a race condition.
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*
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* @param args there must be one arg, "f" or "r", which determines whether the
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* forward (original) list or reversed view of the list is tested
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* @throws InterruptedException if the main thread is interrupted
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*/
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public static void main(String[] args) throws InterruptedException {
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int wrongElement = 0;
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int numExceptions = 0;
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boolean reversed = switch (args[0]) {
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case "f" -> false;
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case "r" -> true;
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default -> throw new IllegalArgumentException();
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};
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list = IntStream.range(0, 10)
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.boxed()
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.collect(Collectors.toCollection(ArrayList::new));
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list = Collections.synchronizedList(list);
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if (reversed)
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list = list.reversed();
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Integer expectedLast = list.getLast();
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ExecutorService pool = Executors.newFixedThreadPool(NUM_WORKERS);
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for (int i = 0; i < NUM_WORKERS; i++)
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pool.submit(() -> {
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while (! Thread.currentThread().isInterrupted()) {
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list.add(0, -1);
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list.remove(0);
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}
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});
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for (int i = 0; i < LOOP_COUNT; i++) {
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Thread.sleep(1L);
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try {
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Integer actualLast = list.getLast();
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if (! expectedLast.equals(actualLast)) {
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++wrongElement;
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}
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} catch (IndexOutOfBoundsException ioobe) {
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++numExceptions;
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}
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}
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pool.shutdownNow();
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pool.awaitTermination(Utils.adjustTimeout(60L), TimeUnit.SECONDS);
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System.out.printf("LOOP_COUNT=%d wrongElement=%d numExceptions=%d%n",
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LOOP_COUNT, wrongElement, numExceptions);
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if (wrongElement == 0 && numExceptions == 0) {
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System.out.println("Test passed.");
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} else {
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throw new AssertionError("TEST FAILED!");
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}
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}
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}
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