Self doubts

Question

Q. The following program consists of 3 concurrent processes and 3 binary semaphore.The semaphore are initialized as s0=1, s1=0, s2=0 .

Process p0

{

    Wait (s0);

Print '0' ;

Release  (s1);

Release (s2);

}

Process p1

Wait (s1);

Release  (s0);

Process p2

Wait (s2);

Release (s0);

How many times will p0 print  '0'?

A) at least twice

B) exactly twice

C)exactly thrice

D)exactly once

My doubt is that , here the processes can also executes  recursively so why they gives ans as "exactly"  term please gives proper explanation my assumption is right or wrong?

Comments

i think something is wrong in question . In process p0 there is an while loop .??

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If there is no while loop then it print exactlly one 0.

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Ya sir  it's my bad during typing  .There is a while loop in p0

Process p0

While(true)

{

//rest is same as above

}

Then, can exactly 3 is the answer  because process p1 and p2 don't have any while loop?

Answer 1

My doubt is that , here the processes can also executes  recursively so why they gives ans as "exactly"  term .

• only process P0 executes recursively becz of while loop. and process P1 and P2 runs only one time.
• if we execute this code then it print two zero or three zero .so option b,c,d are false . 
• option a is right
• 

Comments

Sir more precisely it will not print '0' more than 3 times so why we says at least two (>=2) so here there is a major change needed in option a) that is at most three and at laest 1.

Correct me...!

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Yes option should be atmost  3 zero .

But in option it is not given so i said option a is strongest among all

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Ya ...sir,  thank you so much.