1 /* 2 * Copyright (c) 2004, 2023, 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 8132785 27 * @summary Check that the "java-level" APIs provide a consistent view of 28 * the thread list 29 * @comment Must run in othervm mode to avoid interference from other tests. 30 * @run main/othervm ThreadLists 31 */ 32 import java.lang.management.ManagementFactory; 33 import java.lang.management.ThreadInfo; 34 import java.lang.management.ThreadMXBean; 35 import java.util.Map; 36 import java.util.Set; 37 import java.util.TreeSet; 38 39 public class ThreadLists { 40 41 // Thread names permitted to appear during test: 42 public static final String [] permittedThreadNames = { "ForkJoinPool", "JVMCI" }; 43 44 public static boolean isPermittedNewThread(String name) { 45 for (String s : permittedThreadNames) { 46 if (name.contains(s)) { 47 return true; 48 } 49 } 50 return false; 51 } 52 53 public static void main(String args[]) { 54 55 // Bug id : JDK-8151797 56 // Use a lambda expression so that call-site cleaner thread is started 57 Runnable printLambda = () -> {System.out.println("Starting Test");}; 58 printLambda.run(); 59 60 // start a virutal thread to cause supporting threads to start 61 Thread.startVirtualThread(() -> { }); 62 63 // get top-level thread group 64 ThreadGroup top = Thread.currentThread().getThreadGroup(); 65 ThreadGroup parent; 66 do { 67 parent = top.getParent(); 68 if (parent != null) top = parent; 69 } while (parent != null); 70 71 // get the thread count 72 int tgActiveCount = top.activeCount(); 73 74 // Now enumerate to see if we find any extras yet. 75 // Ensure array is big enough for a few extras. 76 Thread[] tgThreads = new Thread[tgActiveCount * 2]; 77 int tgNewCount = top.enumerate(tgThreads); 78 Map<Thread, StackTraceElement[]> stackTraces = Thread.getAllStackTraces(); 79 80 if (tgNewCount != tgActiveCount) { 81 System.out.println("Found different Thread Group thread count after enumeration: tgActiveCount=" 82 + tgActiveCount + " enumerated=" + tgNewCount); 83 } 84 if (tgNewCount != stackTraces.size()) { 85 System.out.println("Found difference in counts: thread group new count=" 86 + tgNewCount + " stackTraces.size()=" + stackTraces.size()); 87 } 88 System.out.println("Initial set of enumerated threads:"); 89 for (int i = 0; i < tgNewCount; i++) { 90 System.out.println(" - Thread: " + tgThreads[i].getName()); 91 } 92 93 // Get Threads from MXBean. Retry to ensure count and id count match. 94 ThreadMXBean threadBean = ManagementFactory.getThreadMXBean(); 95 int threadCountBean = 0; 96 long[] threadIdsBean = null; 97 do { 98 System.out.println("Gathering Thread info from MXBean..."); 99 threadCountBean = threadBean.getThreadCount(); 100 threadIdsBean = threadBean.getAllThreadIds(); 101 } while (threadCountBean != threadIdsBean.length); 102 103 System.out.println("ThreadGroup: " + tgActiveCount + " active thread(s)"); 104 System.out.println("Thread.getAllStackTraces: " + stackTraces.size() + " stack trace(s) returned"); 105 System.out.println("ThreadMXBean: " + threadCountBean + " live threads(s)"); 106 System.out.println("ThreadMXBean: " + threadIdsBean.length + " thread Id(s)"); 107 108 if (threadIdsBean.length > tgActiveCount) { 109 // Find the new Threads: some Thead names are permitted to appear: ignore them. 110 Set<Long> seenTids = new TreeSet<>(); 111 for (Thread t : stackTraces.keySet()) { 112 if (t != null) { 113 seenTids.add(t.getId()); 114 } 115 } 116 for (long tid : threadIdsBean) { 117 if (!seenTids.contains(tid)) { 118 // New Thread from MBean, compared to Thread Group: 119 ThreadInfo threadInfo = threadBean.getThreadInfo(tid); 120 if (threadInfo != null && isPermittedNewThread(threadInfo.getThreadName())) { 121 System.out.print("New thread permitted: " + threadInfo); 122 threadCountBean--; 123 } 124 } 125 } 126 } 127 128 // check results are consistent 129 boolean failed = false; 130 if (tgActiveCount != stackTraces.size()) failed = true; 131 if (tgActiveCount != threadCountBean) failed = true; 132 // We know threadCountBean == threadIdsBean.length 133 134 if (failed) { 135 System.out.println("Failed."); 136 System.out.println("Set of Threads from getAllStackTraces:"); 137 for (Thread t : stackTraces.keySet()) { 138 System.out.println(" - Thread: " + 139 (t != null ? t.getName() : "null!")); 140 } 141 System.out.println("Set of Thread IDs from MXBean:"); 142 for (long tid : threadIdsBean) { 143 System.out.print(tid + " "); 144 ThreadInfo threadInfo = threadBean.getThreadInfo(tid); 145 System.out.println(threadInfo != null ? threadInfo.getThreadName() : ""); 146 } 147 throw new RuntimeException("inconsistent results"); 148 } 149 } 150 }