Java自定义线程池ThreadPoolExecutor

/**
 * Creates a thread pool that creates new threads as needed, but
 * will reuse previously constructed threads when they are
 * available.  These pools will typically improve the performance
 * of programs that execute many short-lived asynchronous tasks.
 * Calls to {@code execute} will reuse previously constructed
 * threads if available. If no existing thread is available, a new
 * thread will be created and added to the pool. Threads that have
 * not been used for sixty seconds are terminated and removed from
 * the cache. Thus, a pool that remains idle for long enough will
 * not consume any resources. Note that pools with similar
 * properties but different details (for example, timeout parameters)
 * may be created using {@link ThreadPoolExecutor} constructors.
 *
 * @return the newly created thread pool
 */
public static ExecutorService newCachedThreadPool() {
    return new ThreadPoolExecutor(
        0, 
        Integer.MAX_VALUE,
        60L, 
        TimeUnit.SECONDS,
        new SynchronousQueue<Runnable>()
    );
}

/**
 * Creates a thread pool that reuses a fixed number of threads
 * operating off a shared unbounded queue.  At any point, at most
 * {@code 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<Runnable>()
    );
}

/**
 * Creates a new {@code ScheduledThreadPoolExecutor} with the
 * given core pool size.
 *
 * @param corePoolSize the number of threads to keep in the pool, even
 *        if they are idle, unless {@code allowCoreThreadTimeOut} is set
 * @throws IllegalArgumentException if {@code corePoolSize < 0}
 */
public ScheduledThreadPoolExecutor(int corePoolSize) {
    super(corePoolSize, Integer.MAX_VALUE, 0, NANOSECONDS,new DelayedWorkQueue());
}

// 这里的父类是
/**
 * Creates a new {@code ThreadPoolExecutor} with the given initial
 * parameters and default rejected execution handler.
 *
 * @param corePoolSize the number of threads to keep in the pool, even
 *        if they are idle, unless {@code allowCoreThreadTimeOut} is set
 * @param maximumPoolSize the maximum number of threads to allow in the
 *        pool
 * @param keepAliveTime when the number of threads is greater than
 *        the core, this is the maximum time that excess idle threads
 *        will wait for new tasks before terminating.
 * @param unit the time unit for the {@code keepAliveTime} argument
 * @param workQueue the queue to use for holding tasks before they are
 *        executed.  This queue will hold only the {@code Runnable}
 *        tasks submitted by the {@code execute} method.
 * @param threadFactory the factory to use when the executor
 *        creates a new thread
 * @throws IllegalArgumentException if one of the following holds:<br>
 *         {@code corePoolSize < 0}<br>
 *         {@code keepAliveTime < 0}<br>
 *         {@code maximumPoolSize <= 0}<br>
 *         {@code maximumPoolSize < corePoolSize}
 * @throws NullPointerException if {@code workQueue}
 *         or {@code threadFactory} is null
 */
public ThreadPoolExecutor(int corePoolSize,
                            int maximumPoolSize,
                            long keepAliveTime,
                            TimeUnit unit,
                            BlockingQueue<Runnable> workQueue,
                            ThreadFactory threadFactory) {
    this(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue,threadFactory, defaultHandler);
}

/**
 * Creates an Executor that uses a single worker thread operating
 * off an unbounded queue. (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
 * {@code newFixedThreadPool(1)} the returned executor is
 * guaranteed not to be reconfigurable to use additional threads.
 *
 * @return the newly created single-threaded Executor
 */
public static ExecutorService newSingleThreadExecutor() {
    return new FinalizableDelegatedExecutorService(
        new ThreadPoolExecutor(
            1,
            1,
            0L,
            TimeUnit.MILLISECONDS,
            new LinkedBlockingQueue<Runnable>()
        )
    );
}