126 lines
4.0 KiB
Java
126 lines
4.0 KiB
Java
/*
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* Copyright (c) 2022, 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 Test Thread.yield submits the virtual thread task to the expected queue
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* @requires vm.continuations
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* @run junit/othervm -Djdk.virtualThreadScheduler.maxPoolSize=1 YieldQueuing
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*/
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import java.util.List;
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import java.util.concurrent.CopyOnWriteArrayList;
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import java.util.concurrent.atomic.AtomicBoolean;
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import java.util.concurrent.locks.LockSupport;
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import org.junit.jupiter.api.Test;
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import static org.junit.jupiter.api.Assertions.*;
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class YieldQueuing {
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/**
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* Test Thread.yield submits the task for the current virtual thread to a scheduler
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* submission queue when there are no tasks in the local queue.
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*/
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@Test
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void testYieldWithEmptyLocalQueue() throws Exception {
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var list = new CopyOnWriteArrayList<String>();
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var threadsStarted = new AtomicBoolean();
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var threadA = Thread.ofVirtual().unstarted(() -> {
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// pin thread until task for B is in submission queue
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while (!threadsStarted.get()) {
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Thread.onSpinWait();
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}
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list.add("A");
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Thread.yield(); // push task for A to submission queue, B should run
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list.add("A");
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});
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var threadB = Thread.ofVirtual().unstarted(() -> {
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list.add("B");
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});
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// push tasks for A and B to submission queue
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threadA.start();
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threadB.start();
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// release A
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threadsStarted.set(true);
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// wait for result
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threadA.join();
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threadB.join();
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assertEquals(list, List.of("A", "B", "A"));
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}
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/**
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* Test Thread.yield submits the task for the current virtual thread to the local
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* queue when there are tasks in the local queue.
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*/
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@Test
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void testYieldWithNonEmptyLocalQueue() throws Exception {
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var list = new CopyOnWriteArrayList<String>();
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var threadsStarted = new AtomicBoolean();
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var threadA = Thread.ofVirtual().unstarted(() -> {
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// pin thread until tasks for B and C are in submission queue
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while (!threadsStarted.get()) {
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Thread.onSpinWait();
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}
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list.add("A");
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LockSupport.park(); // B should run
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list.add("A");
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});
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var threadB = Thread.ofVirtual().unstarted(() -> {
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list.add("B");
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LockSupport.unpark(threadA); // push task for A to local queue
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Thread.yield(); // push task for B to local queue, A should run
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list.add("B");
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});
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var threadC = Thread.ofVirtual().unstarted(() -> {
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list.add("C");
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});
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// push tasks for A, B and C to submission queue
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threadA.start();
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threadB.start();
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threadC.start();
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// release A
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threadsStarted.set(true);
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// wait for result
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threadA.join();
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threadB.join();
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threadC.join();
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assertEquals(list, List.of("A", "B", "A", "B", "C"));
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}
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}
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