Exercise 3.48 · 习题

Exercise 3.48: Explain in detail why the

deadlock-avoidance method described above, (i.e., the accounts are numbered,

and each process attempts to acquire the smaller-numbered account first) avoids

deadlock in the exchange problem. Rewrite serialized-exchange to

incorporate this idea. (You will also need to modify make-account so

that each account is created with a number, which can be accessed by sending an

appropriate message.)

练习 3.48：请详细说明为何上述死锁规避方法（即对账户编号，并让每个进程总是先尝试获取编号较小的账户）能够在交换问题中避免死锁。请重写 serialized-exchange 以体现这一思路。（你还需要修改 make-account，使每个账户在创建时都带有一个编号，并可通过发送适当消息来访问该编号。）