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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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/**
 * @test
 * @bug 8284161 8287103
 * @summary Test ThredMXBean.findMonitorDeadlockedThreads with cycles of
 *   platform and virtual threads in deadlock
 * @compile --enable-preview -source ${jdk.version} VirtualThreadDeadlocks.java
 * @run main/othervm --enable-preview VirtualThreadDeadlocks PP
 * @run main/othervm --enable-preview VirtualThreadDeadlocks PV
 * @run main/othervm --enable-preview VirtualThreadDeadlocks VV
 */

import java.lang.management.ManagementFactory;
import java.lang.management.ThreadMXBean;
import java.util.Arrays;
import java.util.stream.Stream;

public class VirtualThreadDeadlocks {
    private static final Object LOCK1 = new Object();
    private static final Object LOCK2 = new Object();

    private static volatile boolean lock2Held;

    /**
     * PP = test deadlock with two platform threads
     * PV = test deadlock with one platform thread and one virtual thread
     * VV = test deadlock with two virtual threads
     */
    public static void main(String[] args) throws Exception {

        // start thread1
        Thread.Builder builder1 = (args[0].charAt(0) == 'P')
                ? Thread.ofPlatform().daemon()
                : Thread.ofVirtual();
        Thread thread1 = builder1.start(() -> {
            synchronized (LOCK1) {
                while (!lock2Held) {
                    try { Thread.sleep(10); } catch (Exception e) { }
                }
                synchronized (LOCK2) { }
            }
        });
        System.out.println("thread1 => " + thread1);

        // start thread2
        Thread.Builder builder2 = (args[0].charAt(1) == 'P')
                ? Thread.ofPlatform().daemon()
                : Thread.ofVirtual();
        Thread thread2 = builder2.start(() -> {
            synchronized (LOCK2) {
                lock2Held = true;
                synchronized (LOCK1) { }
            }
        });
        System.out.println("thread2 => " + thread2);

        System.out.println("Waiting for thread1 and thread2 to deadlock ...");
        awaitBlocked(thread1);
        awaitBlocked(thread2);

        ThreadMXBean bean = ManagementFactory.getPlatformMXBean(ThreadMXBean.class);
        long[] deadlockedThreads = sorted(bean.findMonitorDeadlockedThreads());
        System.out.println("findMonitorDeadlockedThreads => " + Arrays.toString(deadlockedThreads));

        // deadlocks involving virtual threads are not detected
        long[] expectedThreads = (!thread1.isVirtual() && !thread2.isVirtual())
            ? sorted(thread1.threadId(), thread2.threadId())
            : null;

        System.out.println("expected => " + Arrays.toString(expectedThreads));

        if (!Arrays.equals(deadlockedThreads, expectedThreads))
            throw new RuntimeException("Unexpected result");
    }

    private static void awaitBlocked(Thread thread) throws InterruptedException {
        while (thread.getState() != Thread.State.BLOCKED) {
            Thread.sleep(10);
        }
    }

    private static long[] sorted(long... array) {
        if (array != null) Arrays.sort(array);
        return array;
    }
}