96 lines
3.2 KiB
Java
96 lines
3.2 KiB
Java
/*
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* Copyright (c) 2023, 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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* @summary Stress test parking and unparking
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* @requires vm.debug != true
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* @run main/othervm ParkALot 500000
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*/
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/*
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* @test
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* @requires vm.debug == true
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* @run main/othervm ParkALot 100000
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*/
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import java.time.Instant;
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import java.util.concurrent.Executors;
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import java.util.concurrent.ThreadFactory;
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import java.util.concurrent.locks.LockSupport;
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public class ParkALot {
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private static final int ITERATIONS = 1_000_000;
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public static void main(String[] args) {
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int iterations;
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if (args.length > 0) {
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iterations = Integer.parseInt(args[0]);
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} else {
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iterations = ITERATIONS;
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}
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int maxThreads = Math.clamp(Runtime.getRuntime().availableProcessors() / 2, 1, 4);
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for (int nthreads = 1; nthreads <= maxThreads; nthreads++) {
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System.out.format("%s %d thread(s) ...%n", Instant.now(), nthreads);
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ThreadFactory factory = Thread.ofPlatform().factory();
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try (var executor = Executors.newThreadPerTaskExecutor(factory)) {
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for (int i = 0; i < nthreads; i++) {
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executor.submit(() -> parkALot(iterations));
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}
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}
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System.out.format("%s %d thread(s) done%n", Instant.now(), nthreads);
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}
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}
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/**
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* Creates a virtual thread that alternates between untimed and timed parking.
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* A platform thread spins unparking the virtual thread.
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*/
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private static void parkALot(int iterations) {
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Thread vthread = Thread.ofVirtual().start(() -> {
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int i = 0;
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boolean timed = false;
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while (i < iterations) {
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if (timed) {
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LockSupport.parkNanos(Long.MAX_VALUE);
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timed = false;
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} else {
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LockSupport.park();
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timed = true;
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}
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i++;
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}
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});
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Thread.State state;
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while ((state = vthread.getState()) != Thread.State.TERMINATED) {
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if (state == Thread.State.WAITING || state == Thread.State.TIMED_WAITING) {
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LockSupport.unpark(vthread);
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} else {
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Thread.yield();
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}
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}
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}
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}
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