说明：  线程池是一钟多线程处理形式，处理过程中将任务添加到队列，然后在创建线程后自动启动这些任务。线程池线程都是后台线程.每个线程都使用默认的堆栈大小,以默认的优先级运行,并处于多线程单元中.如果某个线程在托管代码中空闲(如正在等待某个事件),则线程池将插入另一个辅助线程来使所有处理器保持繁忙.如果所有线程池线程都始终保持繁忙,但队列中包含挂起的工作,则线程池将在一段时间后创建另一个辅助线程但线程的数目永远不会超过最大值.超过最大值的线程可以排队,但他们要等到其他线程完成后才启动
(The thread pool is a bell multithreading process will add the task to the queue, and then start these tasks automatically create a thread. Thread pool threads are background threads Each thread uses the default stack size, the default priority run in a multi-threaded apartment. If a thread is idle for managed code (for example, is waiting for an event), thread pool will insert another worker thread to keep busy so that all processors if all thread pool threads are always kept busy, but contains pending queue, the thread pool will create another worker thread after a certain period of time. the number of threads will never exceed the maximum value exceeds the maximum thread can be queued, but they have to wait until the other thread to complete after the start)