System call

Question

for (int i = 0; i<4; i++) 
{ 
    fork();
}

What is no of child nodes at each level ?

Answer 1

After first fork there will be one child. After second fork, 2 new child processes (as now 2 processes are executing fork)

So at level $i$ (starting from 0) we have $2^{i}$ child processes newly created.

In the given code we have 4 levels and thus $ 1 + 2 + 4 + 8 = 15$ child processes plus 1 parent process. 

In general it will form  complete binary tree when fork is executed in a loop without any further condition. 

  for(i=0; i<n; i++)

No. of child processes created $=2^{n}-1$. 

Comments

pooja i editted the question .Sorry ! Now would you still the same thing ? total no of child process created is 15 and total number of process created is 16

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I dont think  it form a complete binary tree .Whatever link i went through none of them said this :

i went through this link

http://stackoverflow.com/questions/9269590/i-dont-understand-this-diagram-of-fork

And then i made conclusion . And the same thing match with my engineering textbook (for n =3 )

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The answer is correct for the given question. In the stackoverflow link we have condition inside loop to filter out parent.

Answer 2

this is not a question from any book , i just want to verify my understanding how process are getting repliacted at each level

Assuming parent (root at level 1)

So node at level 1 = 1

level 2= 4

level 3 = 6

level 4 = 4

level 5 = 1

And the no of node at each level is also equal to no of print statement at each level .

total process created is 16