A shared variable x, initialized to zero, is operated on by four concurrent processes W,X,Y,Z as follows. Each of W and X reads x from memory, increments b

Question

A shared variable x, initialized to zero, is operated on by four concurrent processes W,X,Y,Z as follows. Each of W and X reads x from memory, increments by one, stores it to memory, and then terminates. Each of 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 (wait) on a counting semaphore S and invokes V (signal) on 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?

Accepted Answer

D. 2

Related Operating Systems PYQs

Turn practice into measurable progress