1
00:00:00,760 --> 00:00:05,140
Hello and welcome to a new section on multiple processes control.

2
00:00:06,190 --> 00:00:13,300
This topic is about how to prevent more than one instance of a process from running concurrently.

3
00:00:16,360 --> 00:00:24,190
Objective, if a process is already running, you do not want to start another similar process.

4
00:00:26,530 --> 00:00:27,370
How to do it.

5
00:00:29,290 --> 00:00:35,110
We use a concept in operating system called process synchronization.

6
00:00:37,230 --> 00:00:45,990
Process synchronization is a task of coordinating the execution of processes in such a way that no two

7
00:00:45,990 --> 00:00:56,370
processes can have access to the same data and resources and data and resources here refers to the memory.

8
00:00:59,210 --> 00:01:00,380
How can we achieve that?

9
00:01:00,920 --> 00:01:03,410
We can use something called locks.

10
00:01:06,540 --> 00:01:07,560
Types of locks.

11
00:01:09,160 --> 00:01:17,920
There are several times on logs, for example, new text, also known as mutants of mutual exclusion

12
00:01:18,070 --> 00:01:20,620
locks or simply locks.

13
00:01:21,070 --> 00:01:25,390
This is the oldest lock that exists in operating systems.

14
00:01:27,430 --> 00:01:36,850
Second is semi false, semaphore is an improved version of a mute lock with additional parameters for

15
00:01:36,850 --> 00:01:37,480
control.

16
00:01:39,730 --> 00:01:42,990
Events also known as event objects.

17
00:01:45,310 --> 00:01:54,910
Name, Price, a time offer used in memory for internal process communication, so it possess once to

18
00:01:54,910 --> 00:01:58,600
prevent another instance of itself from running.

19
00:01:59,110 --> 00:02:08,240
It can acquire one of these and even the second process upon starting finds that any of these locks

20
00:02:08,240 --> 00:02:12,040
how resistant in memory, then he will just squeak.

21
00:02:13,540 --> 00:02:19,480
So that is the idea of how we're are going to implement multiple process control.

22
00:02:20,260 --> 00:02:20,830
Thank you.

23
00:02:20,890 --> 00:02:22,480
I'll see you in the next lesson.