1 /* 2 * Copyright (c) 2013, 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 import java.lang.management.ManagementFactory; 25 import java.lang.management.ThreadMXBean; 26 import java.util.Random; 27 28 /* 29 * @test 30 * @bug 8016304 31 * @summary Make sure no deadlock is reported for this program which has no deadlocks. 32 * @run main/othervm TestFalseDeadLock 33 */ 34 35 /* 36 * This test will not provoke the bug every time it is run since the bug is intermittent. 37 * The test has a fixed running time of 5 seconds. 38 */ 39 40 public class TestFalseDeadLock { 41 private static ThreadMXBean bean; 42 private static volatile boolean running = true; 43 private static volatile boolean found = false; 44 45 public static void main(String[] args) throws Exception { 46 bean = ManagementFactory.getThreadMXBean(); 47 Thread[] threads = new Thread[500]; 48 for (int i = 0; i < threads.length; i++) { 49 Test t = new Test(); 50 threads[i] = new Thread(t); 51 threads[i].start(); 52 } 53 try { 54 Thread.sleep(5000); 55 } catch (InterruptedException ex) { 56 } 57 running = false; 58 for (Thread t : threads) { 59 t.join(); 60 } 61 if (found) { 62 throw new Exception("Deadlock reported, but there is no deadlock."); 63 } 64 } 65 66 public static class Test implements Runnable { 67 public void run() { 68 Random r = new Random(); 69 while (running) { 70 try { 71 synchronized (this) { 72 wait(r.nextInt(1000) + 1); 73 } 74 } catch (InterruptedException ex) { 75 } 76 recurse(2000); 77 } 78 if (bean.findDeadlockedThreads() != null) { 79 System.out.println("FOUND!"); 80 found = true; 81 } 82 } 83 84 private void recurse(int i) { 85 if (!running) { 86 // It is important for the test to call println here 87 // since there are locks inside that path. 88 System.out.println("Hullo"); 89 } 90 else if (i > 0) { 91 recurse(i - 1); 92 } 93 } 94 } 95 }