1 /* 2 * Copyright (c) 2004, 2015, 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 * @test 26 * @bug 5047639 27 * @summary Check that the "java-level" APIs provide a consistent view of 28 * the thread list 29 */ 30 import java.lang.management.ManagementFactory; 31 import java.lang.management.ThreadMXBean; 32 import java.util.Map; 33 34 public class ThreadLists { 35 public static void main(String args[]) { 36 37 // Bug id : JDK-8151797 38 // Use a lambda expression so that call-site cleaner thread is started 39 Runnable printLambda = () -> {System.out.println("Starting Test");}; 40 printLambda.run(); 41 42 // get top-level thread group 43 ThreadGroup top = Thread.currentThread().getThreadGroup(); 44 ThreadGroup parent; 45 do { 46 parent = top.getParent(); 47 if (parent != null) top = parent; 48 } while (parent != null); 49 50 // get the thread count 51 int activeCount = top.activeCount(); 52 53 Map<Thread, StackTraceElement[]> stackTraces = Thread.getAllStackTraces(); 54 55 ThreadMXBean threadBean = ManagementFactory.getThreadMXBean(); 56 int threadCount = threadBean.getThreadCount(); 57 long[] threadIds = threadBean.getAllThreadIds(); 58 59 System.out.println("ThreadGroup: " + activeCount + " active thread(s)"); 60 System.out.println("Thread: " + stackTraces.size() + " stack trace(s) returned"); 61 System.out.println("ThreadMXBean: " + threadCount + " live threads(s)"); 62 System.out.println("ThreadMXBean: " + threadIds.length + " thread Id(s)"); 63 64 // check results are consistent 65 boolean failed = false; 66 if (activeCount != stackTraces.size()) failed = true; 67 if (activeCount != threadCount) failed = true; 68 if (activeCount != threadIds.length) failed = true; 69 70 if (failed) { 71 throw new RuntimeException("inconsistent results"); 72 } 73 } 74 }