Question

QUESTION 13

1. Variable count=0 is shared between processes P0 and P1. P0 executes code count++;. P1 executes code count--; P0 and P1 run concurrently, without any synchronization. Each process runs exactly once. What is the value of count after the execution of both processes?

		1
		0
		-1 or 1
		-1
		-1, 0 or 1

QUESTION 14

1. Six dining philosophers, fully aware of the potential deadlock (and death of starvation), enumerated their chopsticks 0 through 5 and agreed that a hungry philosopher always picks the odd-numbered chopstick and only then the even-numbered chopstick. What kind of deadlock handling strategy is this?

		Deadlock avoidance
		Deadlock prevention
		Deadlock ignoring
		Deadlock detection + resolution

Answer 1

Ques 13. Answer : (b) 0

The possible order in which the processes can run are

• P0 -> P1

P0 : count++

count = count + 1 = 0+ 1

count = 1

P1 : count--

count = count - 1

count = 1 - 1

  count = 0

• P1 -> P1

P1 : count--

count = count - 1

count = 0 - 1

  count = -1

P0 : count++

count = count + 1 = -1 + 1

count = 0

So, the value is same in all cases.

Ques 14. Answer ; (b)

Inn the given condition, then philosophers are picking in a way that a possible deadlock is avoided or prevented. So, it is Deadlock prevention.