Test series

Question

Consider the following Pseudo code:
Process A is :
begin
loop

Non_critical_section;
while not (Turn=1) do
       skip
End while;
       Critical_section_1;
        Turn=2;
   end loop
end
Process B is  
begin
   loop
    Non_critical_section;
    while not (turn=2) do
       skip
End while;
    Critical_section_2;
    Turn=1
   end loop
End

Which of the following statements is/are true? (Assume initially turn =1)

1.   No Mutual exclusion
2.   Mutual exclusion guaranteed, but deadlock will arise.
3.  Mutual exclusion guaranteed, deadlock free, but suffers from starvation.

Answer 1

Process A will enter in its critical section only when turn is equal to one and if process B wants to enter in its critical section its will not enter as turn is one intially (assumed).

So mutual exclusion is there.

But if turn is one intially then process B cannot enter in critical section evenif process A does not want to go in its critical section.so progress is not in there.

So starvation arise but deadlock not .

Comments

yes I agree

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Starvation occurs only if there is no strict alteration. But here as turn is used we have strict alteration so how come starvation can occur?