1 /*

     2  * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 /*

    26  * @test HandshakeWalkSuspendExitTest

    27  * @summary This test tries to stress the handshakes with new and exiting threads while suspending them.

    28  * @library /testlibrary /test/lib

    29  * @build HandshakeWalkSuspendExitTest

    30  * @run driver ClassFileInstaller sun.hotspot.WhiteBox

    31  *                              sun.hotspot.WhiteBox$WhiteBoxPermission

    32  * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI HandshakeWalkSuspendExitTest

    33  */

    34 

    35 import jdk.test.lib.Asserts;

    36 import sun.hotspot.WhiteBox;

    37 

    38 public class HandshakeWalkSuspendExitTest  implements Runnable {

    39 

    40     static final int _test_threads = 8;

    41     static final int _test_exit_threads = 128;

    42     static Thread[] _threads = new Thread[_test_threads];

    43     static volatile boolean exit_now = false;

    44     static java.util.concurrent.Semaphore _sem = new java.util.concurrent.Semaphore(0);

    45 

    46     @Override

    47     public void run() {

    48         WhiteBox wb = WhiteBox.getWhiteBox();

    49         while (!exit_now) {

    50             _sem.release();

    51             // We only suspend threads on even index and not ourself.

    52             // Otherwise we can accidentially suspend all threads.

    53             for (int i = 0; i < _threads.length; i += 2) {

    54                 wb.handshakeWalkStack(null /* ignored */, true /* stackwalk all threads */);

    55                 if (Thread.currentThread() != _threads[i]) {

    56                     _threads[i].suspend();

    57                     _threads[i].resume();

    58                 }

    59             }

    60             for (int i = 0; i < _threads.length; i += 2) {

    61                 wb.handshakeWalkStack(_threads[i] /* thread to stackwalk */, false /* stackwalk one thread */);

    62                 if (Thread.currentThread() != _threads[i]) {

    63                     _threads[i].suspend();

    64                     _threads[i].resume();

    65                 }

    66             }

    67         }

    68     }

    69 

    70     public static void main(String... args) throws Exception {

    71         HandshakeWalkSuspendExitTest test = new HandshakeWalkSuspendExitTest();

    72 

    73         for (int i = 0; i < _threads.length; i++) {

    74             _threads[i] = new Thread(test);

    75             _threads[i].start();

    76         }

    77         for (int i = 0; i < _test_threads; i++) {

    78             _sem.acquire();

    79         }

    80         Thread[] exit_threads = new Thread[_test_exit_threads];

    81         for (int i = 0; i < _test_exit_threads; i++) {

    82             exit_threads[i] = new Thread(new Runnable() { public void run() {} });

    83             exit_threads[i].start();

    84         }

    85         exit_now = true;

    86         for (int i = 0; i < _threads.length; i++) {

    87             _threads[i].join();

    88         }

    89         for (int i = 0; i < exit_threads.length; i++) {

    90             exit_threads[i].join();

    91         }

    92     }

    93 }