jdk-24/jdk/test/java/net/MulticastSocket/MultiDead.java

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/**
 * @test
 * @bug 8072466
 * @summary Deadlock when initializing MulticastSocket and DatagramSocket
 * @library /lib/testlibrary
 * @build jdk.testlibrary.*
 * @run main/othervm MultiDead
 */

import java.net.DatagramSocket;
import java.net.MulticastSocket;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.CountDownLatch;
import jdk.testlibrary.JDKToolLauncher;

public class MultiDead {
    private static final int THREAD_PAIR_COUNT = 4;
    private static final int CHILDREN_COUNT = 20;

    public static void main(String[] args) throws Throwable {
        if (args.length == 0 || args[0].equals("parent")) {
            parentProcess();
        }

        if (args.length > 0 && args[0].equals("child")) {
            childProcess();
        }
    }

    private static void parentProcess() throws Throwable {
        JDKToolLauncher launcher = JDKToolLauncher
                .createUsingTestJDK("java")
                .addToolArg("MultiDead")
                .addToolArg("child");
        ProcessBuilder pb = new ProcessBuilder(launcher.getCommand());

        AtomicReference<Process> child = new AtomicReference<>();
        AtomicBoolean stopFlag = new AtomicBoolean(false);

        Thread th = new Thread(() -> {
            for (int i = 0; i < CHILDREN_COUNT; ++i) {
                System.out.println("child #" + (i + 1) + " of " +
                        CHILDREN_COUNT);
                try {
                    child.set(pb.start());
                    child.get().waitFor();
                    if (stopFlag.get()) {
                        break;
                    }
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            }
        });

        th.start();
        th.join(CHILDREN_COUNT * 1000); // 1 sec for a child to complete
        stopFlag.set(true);
        if (th.isAlive()) {
            if (child.get() != null) {
                child.get().destroyForcibly();
            }
            throw new RuntimeException("Failed to complete on time.");
        }
    }

    private static void childProcess() {
        CountDownLatch latch = new CountDownLatch(1);
        for (int i = 0; i < THREAD_PAIR_COUNT; ++i) {
            new Thread(() -> {
                try {
                    latch.await();
                    try (MulticastSocket a = new MulticastSocket(6000)) {
                    }
                } catch (Exception ignore) {
                }
            }).start();

            new Thread(() -> {
                try {
                    latch.await();
                    try (DatagramSocket b = new DatagramSocket(6000)) {
                    }
                } catch (Exception ignore) {
                }
            }).start();
        }
        latch.countDown();
    }
}