jdk-24/test/jdk/java/lang/Thread/virtual/stress/PingPong.java

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/**
 * @test
 * @summary Stress test virtual threads with SynchronousQueue and LinkedTransferQueue
 * @requires vm.debug != true
 * @compile --enable-preview -source ${jdk.version} PingPong.java
 * @run main/othervm --enable-preview PingPong SQ 1000000
 * @run main/othervm --enable-preview PingPong LTQ 1000000
 */

import java.time.Duration;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.LinkedTransferQueue;
import java.util.concurrent.atomic.AtomicInteger;

public class PingPong {

    public static void main(String[] args) throws Exception {
        Exchanger<String> queue;
        int iterations;
        if (args.length == 0) {
            queue = new LTQExchanger<>();
            iterations = 10_000_000;
        } else {
            if (args[0].equals("SQ")) {
                queue = new SQExchanger<>();
            } else {
                queue = new LTQExchanger<>();
            }
            iterations = Integer.parseInt(args[1]);
        }

        AtomicInteger count1 = new AtomicInteger();
        AtomicInteger count2 = new AtomicInteger();

        Thread t1 = Thread.ofVirtual().start(() -> {
            try {
                while (count1.incrementAndGet() < iterations) {
                    queue.transfer("hello");
                    String reply = queue.take();
                    if (!"ack".equals(reply)) {
                        throw new RuntimeException("reply=" + reply);
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        });

        Thread t2 = Thread.ofVirtual().start(() -> {
            try {
                while (count2.incrementAndGet() < iterations) {
                    String message = queue.take();
                    if (!"hello".equals(message)) {
                        throw new RuntimeException("message=" + message);
                    }
                    queue.transfer("ack");
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        });

        boolean terminated;
        do {
            terminated = t1.join(Duration.ofMillis(500));
            if (terminated)
                terminated = t2.join(Duration.ofMillis(500));
            System.out.format("%d %s%n", count1.get(), count2.get());
        } while (!terminated);

    }

    interface Exchanger<E> {
        void transfer (E value) throws InterruptedException;
        E take() throws InterruptedException;
    }

    static class SQExchanger<E> implements Exchanger<E> {
        private final SynchronousQueue<E> queue = new SynchronousQueue<>();
        @Override
        public void transfer(E value) throws InterruptedException {
            queue.put(value);
        }
        @Override
        public E take() throws InterruptedException {
            return queue.take();
        }
    }

    static class LTQExchanger<E> implements Exchanger<E> {
        private final LinkedTransferQueue<E> queue = new LinkedTransferQueue<>();
        @Override
        public void transfer(E value) throws InterruptedException {
            queue.transfer(value);
        }
        @Override
        public E take() throws InterruptedException {
            return queue.take();
        }
    }
}