e the same as the thread invoking this
     * {@code privilegedThreadFactory} method.  A new
     * {@code privilegedThreadFactory} can be created within an
     * {@link AccessController#doPrivileged AccessController.doPrivileged}
     * action setting the current thread's access control context to
     * create threads with the selected permission settings holding
     * within that action.
     *
     * <p>Note that while tasks running within such threads will have
     * the same access control and class loader settings as the
     * current thread, they need not have the same {@link
     * java.lang.ThreadLocal} or {@link
     * java.lang.InheritableThreadLocal} values. If necessary,
     * particular values of thread locals can be set or reset before
     * any task runs in {@link ThreadPoolExecutor} subclasses using
     * {@link ThreadPoolExecutor#beforeExecute(Thread, Runnable)}.
     * Also, if it is necessary to initialize worker threads to have
     * the same InheritableThreadLocal settings as some other
     * designated thread, you can create a custom ThreadFactory in
     * which that thread waits for and services requests to create
     * others that will inherit its values.
     *
     * @return a thread factory
     *
     * @throws AccessControlException if the current access control
     *                                context does not have permission to both get and set context
     *                                class loader
     */
    // 特权线程工厂
    public static ThreadFactory privilegedThreadFactory() {
        return new PrivilegedThreadFactory();
    }
    
    /*▲ 线程工厂 ████████████████████████████████████████████████████████████████████████████████┛ */
    
    
    
    
    
    
    /*
     * 以下定义了各种类型的：
     *
     * - 任务执行框架
     * - 任务
     * - 线程工厂
 