幾種線程池特點

1. 普通線程池發生異常，會自動創建新的線程填補異常毀掉的線程
2. ScheduledExecutorService按照固定頻率、按照固定延遲發生異常，就會waiting住，導致無法繼續執行，所以需要catch異常，不能拋出異常
3. 按照固定頻率執行，如果任務執行時間超過頻率時間，那麼會連續執行，而按照固定延遲執行，無論執行多久，都會間隔指定時間執行

@Slf4j
class BaseTest {

    private static final ScheduledExecutorService POOL = new ScheduledThreadPoolExecutor(1, r -> {
        Thread t = new Thread(r);
        t.setName("E-POOL");
        return t;
    });

    @Test
    void rateTest() throws Exception {
        AtomicInteger count = new AtomicInteger();
        POOL.scheduleAtFixedRate(() -> {
            System.err.println(123);
            int data = count.incrementAndGet();
            try {
                if (data >= 5) {
                    throw new RuntimeException("123");
                }
            } catch (Exception e) {
                log.error(Throwables.getStackTraceAsString(e));
            }
        }, 1L, 1L, TimeUnit.SECONDS);
        SECONDS.sleep(Long.MAX_VALUE);
    }

    @Test
    void delayTest() throws Exception {
        ThreadFactory threadFactory = new ThreadFactoryBuilder().setNameFormat("my-test-pool-%d").build();
        ScheduledExecutorService scheduledExecutorService = Executors.newScheduledThreadPool(1, threadFactory);
        Date startTime = new Date();
        System.out.println("startTime: " + startTime.toString());
        scheduledExecutorService.scheduleAtFixedRate(() -> {
            System.out.println("beginTime: " + new Date().toString());
            try {
                Thread.sleep(5 * 1000L);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("endTime: " + new Date().toString());
        }, 2, 3, TimeUnit.SECONDS);
        SECONDS.sleep(Long.MAX_VALUE);
    }

    @Test
    void commonTest() throws InterruptedException {
        ExecutorService pool = Executors.newFixedThreadPool(2);
        while (true) {
            pool.execute(() -> {
                // 觀察現成id是否在變化
                System.err.println(Thread.currentThread().getId());
                throw new RuntimeException();
            });
            SECONDS.sleep(1L);
        }
    }
}