94 lines
3.0 KiB
Java
94 lines
3.0 KiB
Java
/*
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* Copyright (c) 2024, 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 id=default
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* @summary Test virtual thread entering (and reentering) a lot of monitors with no contention
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* @library /test/lib
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* @run main LotsOfUncontendedMonitorEnter
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*/
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/*
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* @test id=LM_LEGACY
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* @library /test/lib
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* @run main/othervm -XX:LockingMode=1 LotsOfUncontendedMonitorEnter
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*/
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/*
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* @test id=LM_LIGHTWEIGHT
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* @library /test/lib
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* @run main/othervm -XX:LockingMode=2 LotsOfUncontendedMonitorEnter
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*/
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import java.util.ArrayList;
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import java.util.List;
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import java.util.concurrent.ThreadLocalRandom;
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import jdk.test.lib.thread.VThreadRunner;
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public class LotsOfUncontendedMonitorEnter {
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public static void main(String[] args) throws Exception {
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int depth;
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if (args.length > 0) {
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depth = Integer.parseInt(args[0]);
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} else {
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depth = 24; // 33554430 enters
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}
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VThreadRunner.run(() -> {
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testEnter(List.of(), depth);
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});
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}
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/**
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* Enter the monitor for a new object, reenter a monitor that is already held, and
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* repeat to the given depth.
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*/
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private static void testEnter(List<Object> ownedMonitors, int depthRemaining) {
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if (depthRemaining > 0) {
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var lock = new Object();
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synchronized (lock) {
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// new list of owned monitors
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var monitors = concat(ownedMonitors, lock);
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testEnter(monitors, depthRemaining - 1);
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// reenter a monitor that is already owned
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int index = ThreadLocalRandom.current().nextInt(monitors.size());
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var otherLock = monitors.get(index);
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synchronized (otherLock) {
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testEnter(monitors, depthRemaining - 1);
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}
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}
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}
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}
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/**
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* Adds an element to a list, returning a new list.
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*/
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private static <T> List<T> concat(List<T> list, T object) {
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var newList = new ArrayList<>(list);
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newList.add(object);
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return newList;
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}
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}
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