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/*
* 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");
}
}
}
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