Creating multiple process using fork()
Prerequisite – Introduction of fork, getpid() and getppid()
Problem statement – Write a program to create one parent with three child using fork() function where each process find its Id. For example :
Output :parent
28808 28809
my id is 28807
First child
0 28810
my id is 28808
Second child
28808 0
my id is 28809
third child
0 0
Explanation – Here, we had used fork() function to create four processes one Parent and three child processes.
- An existing process can create a new one by calling the fork( ) function.
- The new process created by fork() is called the child process.
- We are using here getpid() to get the process id
- In fork() the total process created is = 2^number of fork()
Note – At some instance of time, it is not necessary that child process will execute first or parent process will be first allotted CPU, any process may get CPU assigned, at some quantum time. Moreover process id may differ during different executions.
Code 1 – Using getpid()
#include <unistd.h>
#include <stdio.h>
int main()
{
int n1 = fork();
int n2 = fork();
if (n1 > 0 && n2 > 0) {
printf ( "parent\n" );
printf ( "%d %d \n" , n1, n2);
printf ( " my id is %d \n" , getpid());
}
else if (n1 == 0 && n2 > 0)
{
printf ( "First child\n" );
printf ( "%d %d \n" , n1, n2);
printf ( "my id is %d \n" , getpid());
}
else if (n1 > 0 && n2 == 0)
{
printf ( "Second child\n" );
printf ( "%d %d \n" , n1, n2);
printf ( "my id is %d \n" , getpid());
}
else {
printf ( "third child\n" );
printf ( "%d %d \n" , n1, n2);
printf ( " my id is %d \n" , getpid());
}
return 0;
}
|
Output –
parent
28808 28809
my id is 28807
First child
0 28810
my id is 28808
Second child
28808 0
my id is 28809
third child
0 0
Code 2 – Using getppid()
#include <unistd.h>
#include <stdio.h>
int main()
{
int n1 = fork();
int n2 = fork();
if (n1 > 0 && n2 > 0)
{
printf ( "parent\n" );
printf ( "%d %d \n" , n1, n2);
printf ( " my id is %d \n" , getpid());
printf ( " my parentid is %d \n" , getppid());
}
else if (n1 == 0 && n2 > 0)
{
printf ( "First child\n" );
printf ( "%d %d \n" , n1, n2);
printf ( "my id is %d \n" , getpid());
printf ( " my parentid is %d \n" , getppid());
}
else if (n1 > 0 && n2 == 0)
{
printf ( "second child\n" );
printf ( "%d %d \n" , n1, n2);
printf ( "my id is %d \n" , getpid());
printf ( " my parentid is %d \n" , getppid());
}
else {
printf ( "third child\n" );
printf ( "%d %d \n" , n1, n2);
printf ( " my id is %d \n" , getpid());
printf ( " my parentid is %d \n" , getppid());
}
return 0;
}
|
Output –
parent
5219 5220
my id is 5217
my parentid is 5215
First child
0 5221
my id is 5219
my parentid is 1
second child
5219 0
my id is 5220
my parentid is 1
third child
0 0
my id is 5221
my parentid is 1
Last Updated :
09 Oct, 2017
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