engineering/java-topology
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

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

Browse source 
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.
This commit is contained in:
russell@unturf.com 2026-03-26 17:11:57 -04:00
commit 0a580b313d
70422 changed files with 17213626 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

234
test/jdk/java/lang/Thread/virtual/RetryMonitorEnterWhenPinned.java Normal file
View file

@ -0,0 +1,234 @@
/*
* Copyright (c) 2024, 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
* @summary Test that a virtual thread waiting to enter/reenter a monitor, while pinning
* its carrier, will retry until it enters the monitor. This avoids starvation when the
* monitor is exited, an unmounted thread is the chosen successor, and the successor
* can't continue because there are no carriers available.
* @modules java.base/java.lang:+open
* @library /test/lib
* @run junit/othervm/native/timeout=480 --enable-native-access=ALL-UNNAMED RetryMonitorEnterWhenPinned
*/
import java.time.Duration;
import java.time.Instant;
import java.util.ArrayList;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import jdk.test.lib.thread.VThreadPinner;
import jdk.test.lib.thread.VThreadRunner;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.RepeatedTest;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
public class RetryMonitorEnterWhenPinned {
@BeforeAll
static void setup() {
// need >=2 carriers for testing pinning when main thread is a virtual thread
VThreadRunner.ensureParallelism(2);
}
@RepeatedTest(10)
void testMonitorEnter() throws Exception {
var threads = new ArrayList<Thread>();
Object lock = new Object();
synchronized (lock) {
// start virtual threads that block on monitorenter
for (int i = 0; i < 100; i++) {
var started = new CountDownLatch(1);
Thread thread = Thread.startVirtualThread(() -> {
started.countDown();
synchronized (lock) {
spin(20);
}
});
// wait for thread to start and block
started.await();
await(thread, Thread.State.BLOCKED);
threads.add(thread);
}
// start virtual threads that block on monitorenter while pinned
int carriersAvailable = Runtime.getRuntime().availableProcessors();
if (Thread.currentThread().isVirtual()) {
carriersAvailable--;
}
for (int i = 0; i < 100; i++) {
var started = new CountDownLatch(1);
Thread thread = Thread.startVirtualThread(() -> {
started.countDown();
VThreadPinner.runPinned(() -> {
synchronized (lock) {
spin(20);
}
});
});
// if there are carriers available when wait until the thread blocks.
if (carriersAvailable > 0) {
System.out.printf("%s waiting for thread #%d to block%n",
Instant.now(), thread.threadId());
started.await();
await(thread, Thread.State.BLOCKED);
carriersAvailable--;
}
threads.add(thread);
}
} // exit monitor
// wait for all threads to terminate
int threadsRemaining = threads.size();
while (threadsRemaining > 0) {
System.out.printf("%s waiting for %d threads to terminate%n",
Instant.now(), threadsRemaining);
int terminated = 0;
for (Thread t : threads) {
if (t.join(Duration.ofSeconds(1))) {
terminated++;
}
}
threadsRemaining = threads.size() - terminated;
}
System.out.printf("%s done%n", Instant.now());
}
@ParameterizedTest
@ValueSource(ints = { 0, 30000, Integer.MAX_VALUE })
void testMonitorReenter(int timeout) throws Exception {
var threads = new ArrayList<Thread>();
Object lock = new Object();
// start virtual threads that wait on Object.wait
for (int i = 0; i < 100; i++) {
var started = new CountDownLatch(1);
Thread thread = Thread.startVirtualThread(() -> {
try {
synchronized (lock) {
started.countDown();
if (timeout > 0) {
lock.wait(timeout);
} else {
lock.wait();
}
}
} catch (InterruptedException e) { }
});
// wait for thread to start and wait
started.await();
await(thread, timeout > 0 ? Thread.State.TIMED_WAITING : Thread.State.WAITING);
threads.add(thread);
}
// start virtual threads that wait on Object.wait while pinnned
int carriersAvailable = Runtime.getRuntime().availableProcessors();
if (Thread.currentThread().isVirtual()) {
carriersAvailable--;
}
for (int i = 0; i < 100; i++) {
var started = new CountDownLatch(1);
boolean hasCarrier = carriersAvailable > 0;
Thread thread = Thread.startVirtualThread(() -> {
VThreadPinner.runPinned(() -> {
try {
synchronized (lock) {
started.countDown();
if (!hasCarrier) {
// This thread will run at the very
// end and won't be notified.
lock.wait(1);
} else if (timeout > 0) {
lock.wait(timeout);
} else {
lock.wait();
}
}
} catch (InterruptedException e) { }
});
});
// if there are carriers available when wait until the thread blocks.
if (hasCarrier) {
System.out.printf("%s waiting for thread #%d to block%n",
Instant.now(), thread.threadId());
started.await();
await(thread, timeout > 0 ? Thread.State.TIMED_WAITING : Thread.State.WAITING);
carriersAvailable--;
}
threads.add(thread);
}
// wakeup all threads
synchronized (lock) {
lock.notifyAll();
}
// wait for all threads to terminate
int threadsRemaining = threads.size();
while (threadsRemaining > 0) {
System.out.printf("%s waiting for %d threads to terminate%n",
Instant.now(), threadsRemaining);
int terminated = 0;
for (Thread t : threads) {
if (t.join(Duration.ofSeconds(1))) {
terminated++;
}
}
threadsRemaining = threads.size() - terminated;
}
System.out.printf("%s done%n", Instant.now());
}
/**
* Spin for the given number of milliseconds.
*/
static void spin(long millis) {
long nanos = TimeUnit.MILLISECONDS.toNanos(millis);
long start = System.nanoTime();
while ((System.nanoTime() - start) < nanos) {
Thread.onSpinWait();
}
}
/**
* Wait for a thread to reach the expected state.
*/
static void await(Thread thread, Thread.State expectedState) throws InterruptedException {
Thread.State state = thread.getState();
while (state != expectedState) {
assert state != Thread.State.TERMINATED : "Thread has terminated";
Thread.sleep(10);
state = thread.getState();
}
}
}