Question

The following C program is executed on a Unix/Linux system:

#include <unistd.h>
int main() {
  int i;
  for (i=0; i<10; i++)
    if (i%2 == 0) fork();
  return 0;
}

The total number of child processes created is

Accepted Answer

The correct answer is 31. fork() is called when i is even: i=0,2,4,6,8 — 5 fork points. Since every forked child also continues executing the SAME loop independently, each fork point doubles the total number of live processes. Starting from 1 process, after 5 sequential doubling points, total processes = 2^5 = 32. Total CHILDREN created = 32 − 1 (excluding the original parent) = 31.

Explanation