GATE CS 2019 Q17 — System Calls

To find the total number of child processes created, let's analyze the execution of the loop:

The loop variable $i$ ranges from $0$ to $9$. The fork() system call is executed only when the condition i % 2 == 0 is true. This condition is satisfied for the following values of $i$:

This means there are exactly $5$ iterations where a fork() is executed.

Since both the parent and the newly created child processes continue executing the loop from the next iteration, every process existing at the start of an even iteration will execute the fork() call. This doubling effect is identical to executing $5$ consecutive unconditional fork() statements:

• Initially, there is $1$ parent process.
• After the $1^{\text{st}}$ fork (at $i=0$): $2^1 = 2$ processes.
• After the $2^{\text{nd}}$ fork (at $i=2$): $2^2 = 4$ processes.
• After the $3^{\text{rd}}$ fork (at $i=4$): $2^3 = 8$ processes.
• After the $4^{\text{th}}$ fork (at $i=6$): $2^4 = 16$ processes.
• After the $5^{\text{th}}$ fork (at $i=8$): $2^5 = 32$ processes.

At the end of the program, there are $32$ total processes.

The number of child processes created is: