118 lines
4.8 KiB
Java
118 lines
4.8 KiB
Java
/*
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* Copyright (c) 2020, 2022, 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 8240588
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* @summary Use the WhiteBox API to ensure that we can safely access the
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* threadObj oop of a JavaThread during termination, after it has
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* removed itself from the main ThreadsList.
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* @library /testlibrary /test/lib
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* @build jdk.test.whitebox.WhiteBox
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* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
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* @comment run with a small heap, but we need at least 11M for ZGC with JFR
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* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xmx11m -XX:-DisableExplicitGC ThreadObjAccessAtExit
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*/
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import jdk.test.whitebox.WhiteBox;
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// We need to coordinate the actions of the target thread, the GC thread
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// and the WB main test method. To simplify things we use the target
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// thread's priority field to indicate the state of the test as follows:
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// - Start the target thread with priority 5 (NORM_PRIORITY), it will run
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// until its priority is boosted by 1
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// - Start the GC thread, which will spin until the target thread's priority
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// has been boosted by 2
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// - Call into the WB test method and:
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// - Grab a ThreadsListHandle and ensure it contains the target
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// - Increase the target priority by one so it will terminate
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// - Wait until we see the JavaThread has terminated
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// - Increase the target thread priority by one again to release the GC thread
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// - Check the original Thread oop with the target->threadObj to see if they
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// are the same (looping a few times to improve the chances of GC having
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// time to move the underlying object).
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// - If the oop has changed throw an exception
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public class ThreadObjAccessAtExit {
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static class GCThread extends Thread {
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// Allocate a moderate-size array
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static Object[] arr = new Object[64*1024];
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// Wait till we see the main thread is ready then clear the storage
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// we consumed at class initialization and run an explicit GC cycle.
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// This is sufficient (via experimentation) to cause the oop to be
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// relocated.
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public void run() {
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System.out.println("GCThread waiting ... ");
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try {
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while (target.getPriority() != Thread.NORM_PRIORITY + 2) {
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Thread.sleep(10);
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}
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}
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catch(InterruptedException ie) {
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throw new RuntimeException(ie);
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}
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System.out.println("GCThread running ... ");
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arr = null;
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System.gc();
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}
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}
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static Thread target; // for easy access from GCThread
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public static void main(String[] args) throws Throwable {
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WhiteBox wb = WhiteBox.getWhiteBox();
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// Create the GCThread, which performs the initial large
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// allocation that will later be released when it runs.
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GCThread g = new GCThread();
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g.setName("GCThread");
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// Create the target thread (hopefully in a region that will cause
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// it to move when GC happens later).
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target = new Thread("Target") {
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public void run() {
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Thread current = Thread.currentThread();
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// Wait until we are told to terminate by the main thread
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try {
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while (current.getPriority() != Thread.NORM_PRIORITY + 1) {
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Thread.sleep(10);
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}
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}
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catch(InterruptedException ie) {
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throw new RuntimeException(ie);
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}
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System.out.println("Target is terminating");
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}
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};
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g.start();
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target.setPriority(Thread.NORM_PRIORITY); // just to be explicit
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target.start();
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wb.checkThreadObjOfTerminatingThread(target);
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}
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}
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