Runnable과 데몬 스레드

import java.util.concurrent.CountDownLatch;

public final class DaemonCompletionAssumption {
    public static void main(String[] args) {
        CountDownLatch neverReleased = new CountDownLatch(1);
        Thread saver =
                new Thread(
                        () -> {
                            try {
                                neverReleased.await();
                                System.out.println("saved=report");
                            } catch (InterruptedException e) {
                                Thread.currentThread().interrupt();
                            }
                        },
                        "background-save");
        saver.setDaemon(true);
        saver.start();
        System.out.println("main-exits-with-pending=" + saver.isAlive());
    }
}

public final class RunAndStartExceptionRoute {
    public static void main(String[] args) throws InterruptedException {
        Runnable failure =
                () -> {
                    throw new IllegalArgumentException("invalid-task");
                };
        try {
            failure.run();
        } catch (IllegalArgumentException e) {
            System.out.println("direct-caught=" + e.getMessage());
        }
        Thread worker = new Thread(failure, "async-failure");
        worker.setUncaughtExceptionHandler(
                (thread, error) ->
                        System.out.println(
                                "handler=" + thread.getName() + ":" + error.getMessage()));
        worker.start();
        worker.join();
        System.out.println("worker-state=" + worker.getState());
    }
}

import java.util.List;

public final class DocumentIndexTask implements Runnable {
    private final List<String> documents;

    public DocumentIndexTask(List<String> documents) {
        this.documents = List.copyOf(documents);
    }

    @Override
    public void run() {
        for (String document : documents)
            System.out.println(Thread.currentThread().getName() + " indexed " + document);
    }

    public static void main(String[] args) throws InterruptedException {
        Runnable task = new DocumentIndexTask(List.of("thread", "memory"));
        Thread user = new Thread(task, "index-user");
        user.start();
        user.join();
        Thread preview = new Thread(task, "index-preview");
        preview.setDaemon(true);
        preview.start();
        preview.join();
    }
}

import java.time.Instant;
import java.util.List;

public final class ThreadEventLog {
    private static synchronized void log(String event, String value) {
        System.out.printf(
                "%s [%s] %s=%s%n", Instant.now(), Thread.currentThread().getName(), event, value);
    }

    public static void main(String[] args) throws InterruptedException {
        List<String> jobs = List.of("parse", "index", "publish");
        Thread[] workers = new Thread[jobs.size()];
        for (int i = 0; i < jobs.size(); i++) {
            String job = jobs.get(i);
            workers[i] =
                    new Thread(
                            () -> {
                                log("begin", job);
                                log("complete", job);
                            },
                            "pipeline-" + (i + 1));
            workers[i].start();
        }
        for (Thread worker : workers) {
            worker.join();
        }
        log("all-complete", Integer.toString(workers.length));
    }
}

import java.util.concurrent.CountDownLatch;

public final class DaemonGateJoinSolution {
    public static void main(String[] args) throws InterruptedException {
        CountDownLatch release = new CountDownLatch(1);
        Thread saver = new Thread(() -> {
            try {
                release.await();
                System.out.println(Thread.currentThread().getName() + " saved=document");
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
        }, "gate-save");
        saver.setDaemon(true);
        saver.start();
        System.out.println("main releases save");
        release.countDown();
        saver.join();
        System.out.println("main observed termination");
    }
}