lecture07-chapter04 - processes ± Process control block...

Operating Systems
Lecture 07:
Processes (cont) & Threads (Chapter 4)
Anda Iamnitchi
[email protected]
1

Fork Example (from last class)
The following program will create one or more
processes. Show how processes are created
and what is printed to the screen when this
program executes.
2

#include <stdio.h>
main(){
int a, x, y, n;
a=-5;
n=1;
x=-15;
y=-20;
a=fork();
if(a==0)
y=fork();
while (n<3){
if(y==0)
x=fork();
n++;}
printf(“x=%d y=%d a=%d\n”, x, y, a);}
3

Work session:
pair up with your neighbour
4

Execution
of the
Operating System
5

Execution Within
User Processes
6

Summary
The most fundamental concept in a modern OS is the process
The principal function of the OS is to create, manage, and terminate