/* * Copyright (c) 2004, 2023, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * 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. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * @test * @bug 5047639 8132785 * @summary Check that the "java-level" APIs provide a consistent view of * the thread list * @comment Must run in othervm mode to avoid interference from other tests. * @run main/othervm ThreadLists */ import java.lang.management.ManagementFactory; import java.lang.management.ThreadInfo; import java.lang.management.ThreadMXBean; import java.util.Map; import java.util.Set; import java.util.TreeSet; public class ThreadLists { // Thread names permitted to appear during test: public static final String [] permittedThreadNames = { "ForkJoinPool", "JVMCI" }; public static boolean isPermittedNewThread(String name) { for (String s : permittedThreadNames) { if (name.contains(s)) { return true; } } return false; } public static void main(String args[]) { // Bug id : JDK-8151797 // Use a lambda expression so that call-site cleaner thread is started Runnable printLambda = () -> {System.out.println("Starting Test");}; printLambda.run(); // get top-level thread group ThreadGroup top = Thread.currentThread().getThreadGroup(); ThreadGroup parent; do { parent = top.getParent(); if (parent != null) top = parent; } while (parent != null); // get the thread count int tgActiveCount = top.activeCount(); // Now enumerate to see if we find any extras yet. // Ensure array is big enough for a few extras. Thread[] tgThreads = new Thread[tgActiveCount * 2]; int tgNewCount = top.enumerate(tgThreads); Map<Thread, StackTraceElement[]> stackTraces = Thread.getAllStackTraces(); if (tgNewCount != tgActiveCount) { System.out.println("Found different Thread Group thread count after enumeration: tgActiveCount=" + tgActiveCount + " enumerated=" + tgNewCount); } if (tgNewCount != stackTraces.size()) { System.out.println("Found difference in counts: thread group new count=" + tgNewCount + " stackTraces.size()=" + stackTraces.size()); } System.out.println("Initial set of enumerated threads:"); for (int i = 0; i < tgNewCount; i++) { System.out.println(" - Thread: " + tgThreads[i].getName()); } // Get Threads from MXBean. Retry to ensure count and id count match. ThreadMXBean threadBean = ManagementFactory.getThreadMXBean(); int threadCountBean = 0; long[] threadIdsBean = null; do { System.out.println("Gathering Thread info from MXBean..."); threadCountBean = threadBean.getThreadCount(); threadIdsBean = threadBean.getAllThreadIds(); } while (threadCountBean != threadIdsBean.length); System.out.println("ThreadGroup: " + tgActiveCount + " active thread(s)"); System.out.println("Thread.getAllStackTraces: " + stackTraces.size() + " stack trace(s) returned"); System.out.println("ThreadMXBean: " + threadCountBean + " live threads(s)"); System.out.println("ThreadMXBean: " + threadIdsBean.length + " thread Id(s)"); if (threadIdsBean.length > tgActiveCount) { // Find the new Threads: some Thead names are permitted to appear: ignore them. Set<Long> seenTids = new TreeSet<>(); for (Thread t : stackTraces.keySet()) { if (t != null) { seenTids.add(t.getId()); } } for (long tid : threadIdsBean) { if (!seenTids.contains(tid)) { // New Thread from MBean, compared to Thread Group: ThreadInfo threadInfo = threadBean.getThreadInfo(tid); if (threadInfo != null && isPermittedNewThread(threadInfo.getThreadName())) { System.out.print("New thread permitted: " + threadInfo); threadCountBean--; } } } } // check results are consistent boolean failed = false; if (tgActiveCount != stackTraces.size()) failed = true; if (tgActiveCount != threadCountBean) failed = true; // We know threadCountBean == threadIdsBean.length if (failed) { System.out.println("Failed."); System.out.println("Set of Threads from getAllStackTraces:"); for (Thread t : stackTraces.keySet()) { System.out.println(" - Thread: " + (t != null ? t.getName() : "null!")); } System.out.println("Set of Thread IDs from MXBean:"); for (long tid : threadIdsBean) { System.out.print(tid + " "); ThreadInfo threadInfo = threadBean.getThreadInfo(tid); System.out.println(threadInfo != null ? threadInfo.getThreadName() : ""); } throw new RuntimeException("inconsistent results"); } } }