Andrew S. Tanenbaum (OS) Edition 4 Exercise 6 Question 14 (Page No. 466)

Question

Consider the following state of a system with four processes$, P1, P2, P3,$ and $P4,$ and five types of resources, $RS1, RS2, RS3, RS4,$ and $RS5:$

Using the deadlock detection algorithm described in Section $6.4.2,$ show that there is a deadlock in the system. Identify the processes that are deadlocked.

Answer 1

First, the set of unmarked processes, P = (P1 P2 P3 P4)

R1 is not less than or equal to A

R2 is less than A;  Mark P2; A = (0 2 0 3 1); P = (P1 P3 P4)

R1 is not less than or equal to A

R3 is equal to A; Mark P3; A = (0 2 0 3 2); P = (P1 P4)

R1 is not less than or equal to A

R4 is not less than or equal to A

So, processes P1 and P4 remain unmarked. They are deadlocked.

Source: Tanenbaum Solution Manual.