说明：  一个在《ACE程序员指南》16章的线程池的例子，但是书上的代码有问题。我进行了修改，使得多线程的运行更加健壮，不会出现当队列中无消息时，线程池迅速消失的BUG。相信很多ACE初学者发现了此问题，在此卖弄一下。
(an "ACE Programmer's Guide" Chapter 16 of the thread pool examples, but the book on the code problems. My modified so that the multi-threaded operation more robust, not when there were no queues at the news, thread pool rapidly disappearing BUG. Many believe that the ACE beginners discovered this issue in the play about.)