GATEverse — GATE CSE previous year questions

Consider a multi-threaded program with two threads $\mathrm{T} 1$ and $\mathrm{T} 2$ . The threads share two semaphores: $s1$ (initialized to $1$ ) and $s2$ (initialized to $0$ ). The threads also share a global variable $\mathrm{x}$ (initialized to $0$ ). The threads execute the code shown below. //code of T 1 wait (s1); x = x+1; print (x); wait (s2); signal(s1); // code of T2 wait (s1); x= x+1; print (x) ; signal (s2); signal (s1); Which of the following outcomes is/are possible when threads $\mathrm{T} 1$ and $\mathrm{T} 2$ execute concurrently?

(A)

$\mathrm{T} 1$ runs first and prints $1, \mathrm{~T} 2$ runs next and prints $2$

(B)

$\mathrm{T} 2$ runs first and prints $1, \mathrm{~T} 1$ runs next and prints $2$

(C)

$\text{T1}$ runs first and prints $1, \text{T 2}$ does not print anything (deadlock)

(D)

$\mathrm{T} 2$ runs first and prints $1, \mathrm{~T} 1$ does not print anything (deadlock)