synchronization objects for interprocess synchronization and multi-threadiing
线程间、进程间的同步是通过称为“信号量”signal的一类对象来实现的。下面是一个来自msdn的natice code world的列表：
| Name | Relative speed | Cross process | Resource counting | Supported platforms |
| Critical Section | Fast | No | No (exclusive access) | 9x/NT/CE |
| Mutex | Slow | Yes | No (exclusive access) | 9x/NT/CE |
| Semaphore | Slow | Yes | Automatic | 9x/NT |
| Event | Slow | Yes | Yes | 9x/NT/CE |
| Metered Section | Fast | Yes | Automatic | 9x/NT/CE |
1. 如果是进程内同步线程，用critical section，因为他fast。
2. 如果是需要对shared resources做最大值限制，用semaphore。（msdn：A semaphore object is a synchronization object that maintains a count between zero and a specified maximum value. The count is decremented each time a thread completes a wait for the semaphore object and incremented each time a thread releases the semaphore. ）
3. interprocess同步，用mutex,sepaphore之类。
4. Event，有两类：manuaset和autoset。可以用来精准控制线程的执行次序。
