Consider the following multi-threaded code segment (in a mix of C and pseudo-code), invoked by two processes P1 and P2, and each of the processes spawns two threads T1 and T2:int x = 0; // global Lock L1; // global main() { create a thread to execute foo(); // Thread T1 create a thread to execute foo(); // Thread T2 wait for the two threads to finish execution; print (x);} foo() { int y = 0; Acquire L1; x = x + 1; y = y + 1; Release L1; print (y);}Which of the following statement(s) is/are correct?

Process Isolation: Processes $P_1$ and $P_2$ run in separate address spaces. Therefore, each process has its own independent copy of the global variables x and lock L1. The execution of threads in $P_1$ does not affect the address space or variables of $P_2$.

Execution within each Process:

• In each process, the global variable x is initialized to $0$.

• Two threads, $T_1$ and $T_2$, are spawned to execute foo().

• Within foo(), the increment x = x + 1 is enclosed within a critical section protected by Acquire L1 and Release L1. This guarantees mutual exclusion and prevents race conditions.

• Since both threads increment x exactly once, the final value of x in each process is $0 + 1 + 1 = 2$.

• Therefore, both $P_1$ and $P_2$ will print the value of x as 2 (making statement (A) correct and statement (B) incorrect).

Local Variable y:

• The variable y is declared as a local variable inside foo(), meaning it is allocated on each thread's individual private stack.

• Each thread initializes its own y = 0, increments it to $1$, and then prints y.

• Thus, every thread ($T_1$ and $T_2$) in both processes ($P_1$ and $P_2$) will independently print $y = 1$.

• Therefore, statement (D) is correct and statement (C) is incorrect.