Suppose we want to synchronize two concurrent processes P and Q using binary semaphores S and T. The code for the processes P and Q is shown below.
Process P:
while (1) {
W:
print '0';
print '0';
X:
}
Process Q:
while (1) {
Y:
print '1';
print '1';
Z:
}
Synchronization statements can be inserted only at points W, X, Y and Z. Which of the following will always lead to an output staring with '001100110011' ?
A |
P(S) at W, V(S) at X, P(T) at Y, V(T) at Z, S and T initially 1 |
B |
P(S) at W, V(T) at X, P(T) at Y, V(S) at Z, S initially 1, and T initially 0 |
C |
P(S) at W, V(T) at X, P(T) at Y, V(S) at Z, S and T initially 1 |
D |
P(S) at W, V(S) at X, P(T) at Y, V(T) at Z, S initially 1, and T initially 0 |
Process P_{1} will be executed first and then Process P_{2} can be executed next.
At the process P: W=P(S)
X=V(T)
At the process Q: Y=P(T)
Z=V(S)
Here, S=1, T=0 then the process P executes first and then Q, and both can run on process alternate way start with P.