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undefect. CWE-407 — 63 sites patched across 27 ecosystems

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Authors: russell@unturf.com · brackishbert@gmail.com · foxhop.net · TimeHexOn.com

Patches, unit tests, benchmarks, whitepaper, and outreach briefs.
Public domain — no copyright claimed. Use freely.
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russell@unturf.com 2026-03-26 17:11:57 -04:00
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test/jdk/java/lang/management/ThreadMXBean/ResetPeakThreadCount.java Normal file
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/*
* Copyright (c) 2003, 2025, 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 4892507 8020875 8021335
* @summary Basic Test for the following reset methods:
* - ThreadMXBean.resetPeakThreadCount()
* @author Mandy Chung
* @author Jaroslav Bachorik
* @requires test.thread.factory != "Virtual"
* @build ResetPeakThreadCount
* @build ThreadDump
* @run main/othervm ResetPeakThreadCount
*/
import java.lang.management.*;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
public class ResetPeakThreadCount {
// initial number of new threads started
private static final int DAEMON_THREADS_1 = 80;
// Terminate half of the threads started
private static final int TERMINATE_1 = 40;
// start new threads but expected the peak unchanged
private static final int DAEMON_THREADS_2 = 20;
// peak thread count reset before starting new threads
private static final int DAEMON_THREADS_3 = 20;
// barrier for threads communication
private static final Barrier barrier = new Barrier(DAEMON_THREADS_1);
private static final ThreadMXBean mbean = ManagementFactory.getThreadMXBean();
private static volatile boolean testFailed = false;
private static final List<MyThread> threads = new LinkedList<>();
private static final Object liveSync = new Object();
public static void main(String[] argv) throws Exception {
// System threads can be started/terminated during the test execution,
// and they affect resetPeakThreadCount result.
resetPeak();
startThreads(DAEMON_THREADS_1);
int beforeTerminate = checkPeakThreadCount(threads.size() + 1, -1); // + 1 for the current thread
terminateThreads(TERMINATE_1);
// the value should not decrease
int afterTerminate = checkPeakThreadCount(beforeTerminate, -1);
startThreads(DAEMON_THREADS_2);
// expected peak is unchanged
checkPeakThreadCount(-1, afterTerminate);
// reset peak and ensure new threads increase the value
int beforeThreads3 = resetPeak();
startThreads(DAEMON_THREADS_3);
checkPeakThreadCount(threads.size() + 1, -1); // + 1 for the current thread
checkPeakThreadCount(beforeThreads3, -1);
if (testFailed) {
throw new RuntimeException("TEST FAILED.");
}
System.out.println("Test passed");
}
private static void startThreads(int count) throws InterruptedException {
// get current peak thread count
int peak1 = mbean.getPeakThreadCount();
// Start threads and wait to be sure they all are alive
System.out.println("Starting " + count + " threads....");
barrier.set(count);
synchronized (liveSync) {
for (int i = 0; i < count; i++) {
MyThread newThread = new MyThread();
threads.add(newThread);
newThread.start();
}
}
// wait until all threads have started.
barrier.await();
// get peak thread count after daemon threads have started
int peak2 = mbean.getPeakThreadCount();
System.out.println(" Current = " + mbean.getThreadCount() +
" Peak before = " + peak1 + " after: " + peak2);
int current = mbean.getThreadCount();
System.out.println(" Live thread count before returns " + current);
}
private static void terminateThreads(int count) throws InterruptedException {
// get current peak thread count
int peak1 = mbean.getPeakThreadCount();
// Stop daemon threads and wait to be sure they all are dead
System.out.println("Terminating " + count + " threads....");
barrier.set(count);
synchronized(liveSync) {
Iterator<MyThread> iter = threads.iterator();
for (int i = 0; i < count; i++) {
MyThread thread = iter.next();
thread.live = false;
}
liveSync.notifyAll();
}
// wait until daemon threads terminated.
barrier.await();
// get peak thread count after daemon threads have terminated
int peak2 = mbean.getPeakThreadCount();
// assuming no system thread is added
if (peak2 != peak1) {
throw new RuntimeException("Current Peak = " + peak2 +
" Expected to be = previous peak = " + peak1);
}
for (int i = 0; i < count; i++) {
MyThread thread = threads.remove(0);
thread.join();
}
int current = mbean.getThreadCount();
System.out.println(" Live thread count before returns " + current);
}
// Returns peak thread value after reset.
private static int resetPeak() {
int peak3 = mbean.getPeakThreadCount();
int current = mbean.getThreadCount();
// Reset peak thread count
mbean.resetPeakThreadCount();
int afterResetPeak = mbean.getPeakThreadCount();
int afterResetCurrent = mbean.getThreadCount();
System.out.println("Reset peak before = " + peak3 +
" current = " + current +
" after reset peak = " + afterResetPeak +
" current = " + afterResetCurrent);
return afterResetPeak;
}
private static void fail(String msg) {
ThreadDump.threadDump();
throw new RuntimeException(msg);
}
private static int checkPeakThreadCount(int min, int max) {
int value = mbean.getPeakThreadCount();
if (min > 0 && value < min) {
fail("***** Unexpected thread count: " + value + ", minimum expected " + min + " *****");
}
if (max > 0 && value > max) {
fail("***** Unexpected thread count: " + value + ", maximum expected " + max + " *****");
}
return value;
}
// The MyThread thread lives as long as correspondent its live value is true.
private static class MyThread extends Thread {
volatile boolean live;
MyThread() {
live = true;
setDaemon(true);
}
public void run() {
// signal started
barrier.signal();
synchronized(liveSync) {
while (live) {
try {
liveSync.wait(100);
} catch (InterruptedException e) {
System.out.println("Unexpected exception is thrown.");
e.printStackTrace(System.out);
testFailed = true;
}
}
}
// signal about to exit
barrier.signal();
}
}
}