java 다중 루틴 실행 방법의 ThreadPoolExecutor와 Executors 비교

/**
     * Creates a thread pool that reuses a fixed number of threads
     * operating off a shared unbounded queue.  At any point, at most
     * nThreads threads will be active processing tasks.
     * If additional tasks are submitted when all threads are active,
     * they will wait in the queue until a thread is available.
     * If any thread terminates due to a failure during execution
     * prior to shutdown, a new one will take its place if needed to
     * execute subsequent tasks.  The threads in the pool will exist
     * until it is explicitly {@link ExecutorService#shutdown shutdown}.
     *
     * @param nThreads the number of threads in the pool
     * @return the newly created thread pool
     * @throws IllegalArgumentException if {@code nThreads <= 0}
     */
    public static ExecutorService newFixedThreadPool(int nThreads) {
        return new ThreadPoolExecutor(nThreads, nThreads,
                                      0L, TimeUnit.MILLISECONDS,
                                      new LinkedBlockingQueue());
    }

/**
     * Creates a thread pool that creates new threads as needed, but
     * will reuse previously constructed threads when they are
     * available, and uses the provided
     * ThreadFactory to create new threads when needed.
     * @param threadFactory the factory to use when creating new threads
     * @return the newly created thread pool
     * @throws NullPointerException if threadFactory is null
     */
    public static ExecutorService newCachedThreadPool(ThreadFactory threadFactory) {
        return new ThreadPoolExecutor(0, Integer.MAX_VALUE,
                                      60L, TimeUnit.SECONDS,
                                      new SynchronousQueue(),
                                      threadFactory);
    }

/**
     * Creates a single-threaded executor that can schedule commands
     * to run after a given delay, or to execute periodically.
     * (Note however that if this single
     * thread terminates due to a failure during execution prior to
     * shutdown, a new one will take its place if needed to execute
     * subsequent tasks.)  Tasks are guaranteed to execute
     * sequentially, and no more than one task will be active at any
     * given time. Unlike the otherwise equivalent
     * newScheduledThreadPool(1) the returned executor is
     * guaranteed not to be reconfigurable to use additional threads.
     * @return the newly created scheduled executor
     */
    public static ScheduledExecutorService newSingleThreadScheduledExecutor() {
        return new DelegatedScheduledExecutorService
            (new ScheduledThreadPoolExecutor(1));
    }

/**
     * Creates a single-threaded executor that can schedule commands
     * to run after a given delay, or to execute periodically.  (Note
     * however that if this single thread terminates due to a failure
     * during execution prior to shutdown, a new one will take its
     * place if needed to execute subsequent tasks.)  Tasks are
     * guaranteed to execute sequentially, and no more than one task
     * will be active at any given time. Unlike the otherwise
     * equivalent newScheduledThreadPool(1, threadFactory)
     * the returned executor is guaranteed not to be reconfigurable to
     * use additional threads.
     * @param threadFactory the factory to use when creating new
     * threads
     * @return a newly created scheduled executor
     * @throws NullPointerException if threadFactory is null
     */
    public static ScheduledExecutorService newSingleThreadScheduledExecutor(ThreadFactory threadFactory) {
        return new DelegatedScheduledExecutorService
            (new ScheduledThreadPoolExecutor(1, threadFactory));
    }