Operating Systems | Process Management | Question 6
A shared variable x, initialized to zero, is operated on by four concurrent processes W, X, Y, Z as follows. Each of the processes W and X reads x from memory, increments by one, stores it to memory, and then terminates. Each of the processes Y and Z reads x from memory, decrements by two, stores it to memory, and then terminates. Each process before reading x invokes the P operation (i.e., wait) on a counting semaphore S and invokes the V operation (i.e., signal) on the semaphore S after storing x to memory. Semaphore S is initialized to two. What is the maximum possible value of x after all processes complete execution? (GATE CS 2013)
(A) -2
(B) -1
(C) 1
(D) 2
Answer: (D)
Explanation: See https://www.geeksforgeeks.org/operating-systems-process-management-question-11/ for explanation.
Quiz of this Question
Last Updated :
28 Jun, 2021
Like Article
Save Article
Share your thoughts in the comments
Please Login to comment...