英国帝国理工学院电脑系多线程课程教学材料之四 ---- 用Semaphores互斥访问-The program uses a semaphore to ensure that it is not possible for threads to enter their critical sections at the same time. The critical section is represented by a light blue (cyan) colour. To execute in this region, a thread must have acquired mutual exclusion by executing a down() operation on the semaphore Mutex. The length of time each thread spends in its critical section may be adjusted using the slider control. Further to the right increases this time. The adjustment takes effect at the beginning of each revolution.