sleep & yield

sleep

1. 调用 sleep 会让当前线程从 Running 进入 Timed Waiting 状态（阻塞）
2. 其它线程可以使用 interrupt 方法打断正在睡眠的线程，这时 sleep 方法会抛出 InterruptedException
3. 睡眠结束后的线程未必会立刻得到执行
4. 建议用 TimeUnit 的 sleep 代替 Thread 的 sleep 来获得更好的可读性

@Slf4j
public class Demo {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        log.info("main run..");
        Thread thread = new Thread(() -> {
            log.info("thread run..");
            try {
                TimeUnit.SECONDS.sleep(2);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }, "custom-name");

        thread.start();
        log.info("custom-name state {}", thread.getState());

        TimeUnit.MILLISECONDS.sleep(500);
        log.info("custom-name state {}", thread.getState());

    }
}
//22:57:16.793 [main] INFO com.gao.Demo - main run..
//22:57:16.839 [custom-name] INFO com.gao.Demo - thread run..
//22:57:16.838 [main] INFO com.gao.Demo - custom-name state RUNNABLE
//22:57:17.343 [main] INFO com.gao.Demo - custom-name state TIMED_WAITING

sleep 打断

@Slf4j
public class Demo {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        log.info("main run..");
        Thread thread = new Thread(() -> {
            log.info("{}", Thread.currentThread().getName() + "run..");
            try {
                TimeUnit.SECONDS.sleep(5);
            } catch (InterruptedException e) {
                log.error(e.getMessage());
                throw new RuntimeException(e);
            }
        }, "custom-thread");
        thread.start();

        TimeUnit.SECONDS.sleep(2);
        thread.interrupt();
    }
}

yield

1. 调用 yield 会让当前线程从 Running 进入 Runnable 就绪状态，然后调度执行其它线程
2. 具体的实现依赖于操作系统的任务调度器

@Slf4j
public class Demo {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        log.info("main run..");
        Thread thread = new Thread(() -> {
            log.info("{}", Thread.currentThread().getName() + "run..");
            try {
                Thread.yield();
                TimeUnit.SECONDS.sleep(5);
            } catch (InterruptedException e) {
                log.error(e.getMessage());
                throw new RuntimeException(e);
            }
        }, "custom-thread");
        thread.start();


        TimeUnit.SECONDS.sleep(2);
        thread.interrupt();

    }
}