Gate CS-2013 Question Paper With Solutions

Q. 16 Three concurrent processes X, Y , and Z execute three different code segments that
access and update certain shared variables. Process X executes the P operation
(i.e., wait) on semaphores a, b and c; process Y executes the P operation on
semaphores b, c and d ; process Z executes the P operation on semaphores c
, d , and a before entering the respective code segments. After completing the
execution of its code segment, each process invokes the V operation (i.e., signal)
on its three semaphores. All semaphores are binary semaphores initialized to one.
Which one of the following represents a deadlock-free order of invoking the P
operations by the processes?

(A) X: P(a)P(b)P(c) Y: P(b)P(c)P(d) Z: P(c)P(d)P(a)

(B) X: P(b)P(a)P(c) Y: P(b)P(c)P(d) Z: P(a)P(c)P(d)

(C) X: P(b)P(a)P(c) Y: P(c)P(b)P(d) Z: P(a)P(c)P(d)

(D) X: P(a)P(b)P(c) Y: P(c)P(b)P(d) Z: P(c)P(d)P(a)

Answer: (B)

Explanation:

Gate CS-2013 Question Paper With Solutions

Gate CS-2013 Question Paper With Solutions

Learn More:   Gate EC-2019 Question Paper With Solutions

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