about fork method

[Quratulain2009]

function M1()
{
for(i=1;i<5;i++)
fork();
}

how many child in memory?

A) 1
B) 4
C) 0

or any other.

[zorthian]

Originally Posted by Quratulain2009

function M1()
{
for(i=1;i<5;i++)
fork();
}

how many child in memory?

A) 1
B) 4
C) 0

or any other.

The key thing here is that each child process inherits the current value of i from its parent.
Here's the spawn hierarchy:
P (original parent process)
4 ( child threads)
(3 2 1 0) --> (no. of threads forked by each of the threads in the previous level)
( (2 1 0) ( 1 0) (0) )
(( (1 0) (0) ) ( (0) ) )
((( (0) )))

Adding, we get 15 child processes. The way to read the above is each non-zero entry 'i' in one level expands to i entries in the next level.

- Zorth.

[Enigma211]

Is the analysis accurate here ?

When first time fork is called with i=1 the child process will inherit the same value for i and then fork itself again. Doesn't this look like endless forks ?

[blah321]

No endless forks, because the child does not start running from the beginning - it starts from just after the 'fork();' statement (just like the parent, which also continues executing any statement after the 'fork();')
Child is created with i=1. There is no statement after fork();, so the child continues the loop (i++), and creates a grandchild with i=2...