java-topology/test/jdk/java/lang/Thread/virtual/stress/ParkAfterTimedPark.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
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/*
 * @test id=parked
 * @bug 8369227
 * @summary Stress test untimed park after a timed park when a thread is unparked around the
 *     same time that the timeout expires.
 * @library /test/lib
 * @run main/othervm --enable-native-access=ALL-UNNAMED ParkAfterTimedPark 200 false
 */

/*
 * @test id=pinned
 * @summary Stress test untimed park, while pinned, and after a timed park when a thread is
 *     unparked around the same time that the timeout expires.
 * @library /test/lib
 * @run main/othervm --enable-native-access=ALL-UNNAMED ParkAfterTimedPark 200 true
 */

import java.time.Instant;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.LockSupport;
import jdk.test.lib.thread.VThreadPinner;

public class ParkAfterTimedPark {
    public static void main(String[] args) throws Exception {
        int iterations = (args.length > 0) ? Integer.parseInt(args[0]) : 100;
        boolean pinned = (args.length > 1) ? Boolean.parseBoolean(args[1]) : false;

        for (int i = 1; i <= iterations; i++) {
            System.out.println(Instant.now() + " => " + i + " of " + iterations);
            for (int timeout = 1; timeout <= 10; timeout++) {
                test(timeout, pinned);
            }
        }
    }

    /**
     * Creates two virtual threads. The first does a timed-park for the given time,
     * then parks in CountDownLatch.await. A second virtual thread unparks the first
     * around the same time that the timeout for the first expires.
     */
    private static void test(int millis, boolean pinned) throws Exception {
        long nanos = TimeUnit.MILLISECONDS.toNanos(millis);

        var finish = new CountDownLatch(1);

        Thread thread1 = Thread.startVirtualThread(() -> {
            LockSupport.parkNanos(nanos);
            boolean done = false;
            while (!done) {
                try {
                    if (pinned) {
                        VThreadPinner.runPinned(() -> {
                            finish.await();
                        });
                    } else {
                        finish.await();
                    }
                    done = true;
                } catch (InterruptedException e) { }
            }
        });

        Thread thread2 = Thread.startVirtualThread(() -> {
            int delta = ThreadLocalRandom.current().nextInt(millis);
            boolean done = false;
            while (!done) {
                try {
                    Thread.sleep(millis - delta);
                    done = true;
                } catch (InterruptedException e) { }
            }
            LockSupport.unpark(thread1);
        });

        // wait for first thread to park before count down
        await(thread1, Thread.State.WAITING);
        finish.countDown();

        thread1.join();
        thread2.join();
    }

    /**
     * Waits for the given thread to reach a given state.
     */
    private static void await(Thread thread, Thread.State expectedState) throws Exception {
        Thread.State state = thread.getState();
        while (state != expectedState) {
             if (state == Thread.State.TERMINATED)
                 throw new RuntimeException("Thread has terminated");
            Thread.sleep(10);
            state = thread.getState();
        }
    }
}