?? ??? ???? ??? ??? ?????. ?? ???? ?? ???? ??? ?? ? ??? ??? ?? ? ???? ??? ? ?? ExecutorService? ???? ?? ???? ?? ?? ????? ?????.

??? ??? ????.

public static void main(String[] args) {
    ExecutorService executorService = Executors.newFixedThreadPool(5);
    for (int i = 0; i < 5; i++) {
        int temp = i;
        executorService.submit(() -> {
            task(temp);
        });
    }
    executorService.shutdown();
    System.out.println("ExecutorService is shutdown");
}

private static void task(int temp) {
    try {
        TimeUnit.SECONDS.sleep(1L);
        System.out.println("Task " + temp + " completed");
    } catch (InterruptedException e) {
        throw new RuntimeException(e);
    }
}

?? ??? ?? "sleep"? ?? ??? ???? ???? ??? ???? ?? ?? ???? ????.

?????.

ExecutorService is shutdown
Task 1 completed
Task 2 completed
Task 0 completed
Task 4 completed
Task 3 completed

?? ??? ??? ??? ??? ???? ??? ??? ???. ??? ???? ???? ??????? ?? ?? ?? ??? ?? ????.

?? ?? ?? ?? ??? ??? ???? ?? ??? ????. ?? ?? ??? ?? 5???, ? ???? ?? ??? ?? ????.

??? ?? ?? ???? ??? ?? ??? ?????.

?? ??? ???? ??? ??? ? ? ????

?? ?? ??? ?? ExecutorService.shutdown()? ???? ?? ???? ?? ??? ? ??? ????? ???? ??? ??? ??? ???? ?????. ?? ??? ?? ? ?? ??? ????

? ?? ???? ?????.

1. CountDownLatch? ???? ?? ?? ????? ?? ?? ??? ??? ???? ?? ???????.
2. ExecutorService.awaitTermination()? ?????. ??? ??? ??? ?? ????? ????. ?? ???? ExecutorService.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS) ?? ?? ??? ?? ??? ? ????. ??? ?? ? ??????.

? ??? ??? ? ?? ? ?? ??? ????

Java? ? ??? ??? ? ?? ? ?? ????? ???? ?? ??? ?????. ??? "??"? Executors.newFixedThreadPool? ????? ?? ??? ?? ?? ThreadPoolExecutor?? ?? ?? ????. Executors.newFixedThreadPool? ??? ??? ?????.

public static ExecutorService newFixedThreadPool(int nThreads) {
    return new ThreadPoolExecutor(nThreads, nThreads,
                                  0L, TimeUnit.MILLISECONDS,
                                  new LinkedBlockingQueue<Runnable>());
}

???? ThreadPoolExecutor? ?? ??? ?? ??? ????. ExecutorService? ThreadPoolExecutor? ?? ??? ?????.

... ?????? ?? ??? Executors ??? ??? Executors.newCachedThreadPool()(?? ??? ?? ??? ?? ??? ??? ?), Executors.newFixedThreadPool(int)(?? ?? ??? ?) ? Executors.newSingleThreadExecutor( )(?? ????? ???), ?? ???? ?? ????? ?? ??? ?? ?????.

?? ??? ??? ?? ??? ??? ????.

?? ??

? ???? ? ?? ?? ??? ???? ??? ??? beforeExecute(Thread, Runnable) ? afterExecute(Runnable, Throwable) ???? ?????. ?? ?? ??? ???? ? ??? ? ????. ?? ?? ThreadLocals ?? ???, ?? ?? ?? ?? ?? ?? ?? ????. ??, Executor? ??? ??? ? ????? ?? ?? ??? ???? ?? ??() ???? ???? ? ????.

?? ??? ???? ??? ??? ??? ? ????! ??? ??? ??????

public static void main(String[] args) {
    ExecutorService executorService = Executors.newFixedThreadPool(5);
    for (int i = 0; i < 5; i++) {
        int temp = i;
        executorService.submit(() -> {
            task(temp);
        });
    }
    executorService.shutdown();
    System.out.println("ExecutorService is shutdown");
}

private static void task(int temp) {
    try {
        TimeUnit.SECONDS.sleep(1L);
        System.out.println("Task " + temp + " completed");
    } catch (InterruptedException e) {
        throw new RuntimeException(e);
    }
}

??? ?? ???? ???? ?? ?? ???? ThreadPoolExecutor? ?? ???? ??? ?? ???? ?? ? ????.

ExecutorService is shutdown
Task 1 completed
Task 2 completed
Task 0 completed
Task 4 completed
Task 3 completed

???? ????? ???? ?? ??? ??? ????.

public static ExecutorService newFixedThreadPool(int nThreads) {
    return new ThreadPoolExecutor(nThreads, nThreads,
                                  0L, TimeUnit.MILLISECONDS,
                                  new LinkedBlockingQueue<Runnable>());
}

??? ???? ????? ???? ?? ?? ???? ?????? ??? ?????!

? ??? ExecutorService ?? ????: ThreadPool ?? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!