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

 *

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

 * published by the Free Software Foundation.

 *

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

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

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

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

 * accompanied this code).

 *

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

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

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

 *

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/*

 * @test HandshakeWalkSuspendExitTest

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

 * @library /testlibrary /test/lib

 * @build HandshakeWalkSuspendExitTest

 * @run driver ClassFileInstaller sun.hotspot.WhiteBox

 *                              sun.hotspot.WhiteBox$WhiteBoxPermission

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

 */

import jdk.test.lib.Asserts;

import sun.hotspot.WhiteBox;

public class HandshakeWalkSuspendExitTest  implements Runnable {

    static final int _test_threads = 8;

    static final int _test_exit_threads = 128;

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

    static volatile boolean exit_now = false;

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

    @Override

    public void run() {

        WhiteBox wb = WhiteBox.getWhiteBox();

        while (!exit_now) {

            _sem.release();

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

            // Otherwise we can accidentially suspend all threads.

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

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

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

                    _threads[i].suspend();

                    _threads[i].resume();

                }

            }

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

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

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

                    _threads[i].suspend();

                    _threads[i].resume();

                }

            }

        }

    }

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

        HandshakeWalkSuspendExitTest test = new HandshakeWalkSuspendExitTest();

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

            _threads[i] = new Thread(test);

            _threads[i].start();

        }

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

            _sem.acquire();

        }

        Thread[] exit_threads = new Thread[_test_exit_threads];

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

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

            exit_threads[i].start();

        }

        exit_now = true;

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

            _threads[i].join();

        }

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

            exit_threads[i].join();

        }

    }

}