ISRO | ISRO CS 2013 | Question 57

Consider the following process and resource requirement of each process.

                 Type 1        Type 2
Process         Used  Max      Used  Max
   P1            1     2         1    3
   P2            1     3         1    2
   P3            2     4         1    4 

Predict the state of this system, assuming that there are a total of 5 instances of resource type 1 and 4 instances of resource type 2.

(A) Can go to safe or unsafe state based on sequence

(B) Safe state
(C) Unsafe state
(D) Deadlock state


Answer: (C)

Explanation: Need Matrix of the processes:

         Type 1              Type 2
Process   Used  Max  Need     Used  Max  Need
   P1      1     2    1         1    3    2
   P2      1     3    2         1    2    2
   P3      2     4    2         1    4    3

Available resources : type1 = 5 – 4 = 1 and type2 = 4 – 3 = 1

But with one resource of type1 and type2 each, none of the process request can be fulfilled, so it is an unsafe state.

Option (C) is correct.


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