Gate CS-2010 Question Paper With Solutions

Q. 43 A system has n resources R0..Rn-1, and k processes P0..Pk-1.The implementation
of the resource request logic of each process Pi, is as follows:

if (i % 2 == 0) {
      if (i < n) request Ri
      if (i+2 < n) request Ri+2
}
else {
      if (i < n) request Rn-i
      if (i+2 < n) request Rn-i-2
}

In which one of the following situations is a deadlock possible ?

(A) n = 40,k = 26

(B) n = 21,k = 12

(C) n = 20,k = 10

(D) n = 41,k = 19

Answer: (B)

Explanation: