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

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.

test/jdk/java/lang/Thread/virtual/stress/ParkALot.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2023, 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 Stress test parking and unparking
+ * @requires vm.debug != true
+ * @library /test/lib
+ * @run main/othervm/timeout=1200 ParkALot 300000
+ */
+
+/*
+ * @test
+ * @requires vm.debug == true
+ * @library /test/lib
+ * @run main/othervm/timeout=1200 ParkALot 100000
+ */
+
+import java.time.Instant;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.LockSupport;
+import jdk.test.lib.Platform;
+
+public class ParkALot {
+
+    public static void main(String[] args) throws Exception {
+        int iterations;
+        int value = Integer.parseInt(args[0]);
+        if (Platform.isOSX()) {
+            // reduced iterations on macosx
+            iterations = Math.max(value / 4, 1);
+        } else {
+            iterations = value;
+        }
+
+        int maxThreads = Math.clamp(Runtime.getRuntime().availableProcessors() / 2, 1, 4);
+        for (int nthreads = 1; nthreads <= maxThreads; nthreads++) {
+            System.out.format("%s %d thread(s) ...%n", Instant.now(), nthreads);
+            ThreadFactory factory = Thread.ofPlatform().factory();
+            try (var executor = Executors.newThreadPerTaskExecutor(factory)) {
+                var totalIterations = new AtomicInteger();
+                for (int i = 0; i < nthreads; i++) {
+                    executor.submit(() -> parkALot(iterations, totalIterations::incrementAndGet));
+                }
+
+                // shutdown, await for all threads to finish with progress output
+                executor.shutdown();
+                boolean terminated = false;
+                while (!terminated) {
+                    terminated = executor.awaitTermination(1, TimeUnit.SECONDS);
+                    System.out.format("%s => %d of %d%n",
+                            Instant.now(), totalIterations.get(), iterations * nthreads);
+                }
+            }
+            System.out.format("%s %d thread(s) done%n", Instant.now(), nthreads);
+        }
+    }
+
+    /**
+     * Creates a virtual thread that alternates between untimed and timed parking.
+     * A platform thread spins unparking the virtual thread.
+     * @param iterations number of iterations
+     * @param afterIteration the task to run after each iteration
+     */
+    private static void parkALot(int iterations, Runnable afterIteration) {
+        Thread vthread = Thread.ofVirtual().start(() -> {
+            int i = 0;
+            boolean timed = false;
+            while (i < iterations) {
+                if (timed) {
+                    LockSupport.parkNanos(Long.MAX_VALUE);
+                    timed = false;
+                } else {
+                    LockSupport.park();
+                    timed = true;
+                }
+                i++;
+                afterIteration.run();
+            }
+        });
+
+        Thread.State state;
+        while ((state = vthread.getState()) != Thread.State.TERMINATED) {
+            if (state == Thread.State.WAITING || state == Thread.State.TIMED_WAITING) {
+                LockSupport.unpark(vthread);
+            } else {
+                Thread.yield();
+            }
+        }
+    }
+}