1 /*
   2  * Copyright (c) 2019, 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 HandshakeSuspendExitTest
  27  * @summary This test tries to stress the handshakes with new and exiting threads while suspending them.
  28  * @library /testlibrary /test/lib
  29  * @build HandshakeSuspendExitTest
  30  * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:GuaranteedSafepointInterval=1 -XX:+HandshakeALot HandshakeSuspendExitTest
  31  */
  32 
  33 public class HandshakeSuspendExitTest  implements Runnable {
  34 
  35     static Thread[] _suspend_threads = new Thread[16];
  36     static volatile boolean _exit_now = false;
  37     static java.util.concurrent.Semaphore _sem = new java.util.concurrent.Semaphore(0);
  38 
  39     @Override
  40     public void run() {
  41         _sem.release();
  42         while (!_exit_now) {
  43             int i = 0;
  44             for (Thread thr : _suspend_threads) {
  45                 if (i++ > _suspend_threads.length -2) {
  46                     // Leave last 2 threads running.
  47                     break;
  48                 }
  49                 if (Thread.currentThread() != thr) {
  50                     thr.suspend();
  51                     thr.resume();
  52                 }
  53             }
  54         }
  55         _sem.release();
  56     }
  57 
  58     public static void main(String... args) throws Exception {
  59         HandshakeSuspendExitTest test = new HandshakeSuspendExitTest();
  60         // Fire-up suspend thread.
  61         for (int i = 0; i < _suspend_threads.length; i++) {
  62             _suspend_threads[i] = new Thread(test);
  63         }
  64         for (int i = 0; i < _suspend_threads.length; i++) {
  65             _suspend_threads[i].start();
  66         }
  67         // Wait for all suspend thread starting to loop.
  68         for (Thread thr : _suspend_threads) {
  69             _sem.acquire();
  70         }
  71 
  72         // Fire-up exiting threads.
  73         Thread[] exit_threads = new Thread[128];
  74         for (int i = 0; i < exit_threads.length; i++) {
  75             exit_threads[i] = new Thread(new Runnable() { public void run() {} });
  76             exit_threads[i].start();
  77         }
  78 
  79         // Try to suspend them.
  80         for (Thread thr : exit_threads) {
  81             thr.suspend();
  82         }
  83         for (Thread thr : exit_threads) {
  84             thr.resume();
  85         }
  86 
  87         // Start exit and join.
  88         _exit_now = true;
  89         int waiting = _suspend_threads.length;
  90         do {
  91             for (Thread thr : _suspend_threads) {
  92                 thr.resume();
  93             }
  94             while (_sem.tryAcquire()) {
  95                 --waiting;
  96             }
  97         } while (waiting > 0);
  98         for (Thread thr : _suspend_threads) {
  99             thr.join();
 100         }
 101         for (Thread thr : exit_threads) {
 102             thr.join();
 103         }
 104     }
 105 }