How we can create a zombie process?

Question

As far as i know when a process is created, 8MB of stack is allocated to it.
Is it right?

If not then is there any fix size or not?

If yes then please answer and Help To solve this question also.

Answer 1

Zombie is a process state where process does not actually exist. It mostly happen when child dies But when

Check the following program

#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>

int main ()
{
  pid_t child_pid;

  child_pid = fork ();
  if (child_pid > 0) { // Parent Process
    sleep (60);
  }
  else {
    exit (0); // Child Process
  }
  return 0;
}

When you run the above program and see the process details after 2-3 second (ps -e -o pid,ppid,stat,cmd) you will see the child process is marked as and its status code is Z, for zombie. Whenever parent process completes the processing and exit then zombie state for the non-existing child process gets cleared automatically.

Answer 2

Follow the few steps to create a zombie process:

1. Create a child process using fork system call.
2. Make parent process busy or sleep for some amount of time.
3. Make sure that child process should not involve in very extensive processing. I mean to say just put few simple statement and let the child process exit.
4. Since the parent process is busy or in sleep mode and child process has been already finished its job and exited. We say child process is zombie now since parent has not yet received its's exit status and its entry still exists in process table.

Please correct me if I have missed something.