Exercise 3.46 · 习题

Exercise 3.46: Suppose that we implement

test-and-set! using an ordinary procedure as shown in the text, without

attempting to make the operation atomic. Draw a timing diagram like the one in

Figure 3.29 to demonstrate how the mutex implementation can fail by

allowing two processes to acquire the mutex at the same time.

练习 3.46：假设我们按正文所示，用普通过程实现 test-and-set!，而不试图使该操作成为原子操作。画出类似图 3.29 的时序图，说明互斥体的实现是如何因允许两个进程同时获取互斥体而失效的。