Multithreading in-java

MPhil. Scholar
Computer Science
@ SALU, Khairpur Mir’s

AGENDA
Process in OS
Thread in Java
Deference b/w Thread and Process
Multithreading in Java
Implementation of Multithreading in Java
Advantages of Multithreading
Conclusion

PROCESSOR
PROCESS IN OPERATING SYSTEM
 Process is a program in execution
 Process is not as same as program code but a lot more than it
 Process may be made up of multiple threads of execution that execute instructions
concurrently
MUSIC
PLAYER
MS-WORD
OS SWITCHING
PROCESS-1
PROCESS-1

A thread is a light-weight smallest part of a process that can run
concurrently with the other parts(other threads) of the same process.
Threads are independent because they all have separate path of
execution that’s the reason if an exception occurs in one thread, it
doesn’t affect the execution of other threads. All threads of a process
share the common memory. .
Thread in Java

Deference b/w Process and Thread
Threads:
1.Threads are light weight
processes. Threads are bundled
inside the process.
2.Threads have a shared memory,
data, resources, files etc.
3.Threads are created using clone()
method.
4.Context switch between the
threads are not much time
consuming as Process.
Example:
Opening multiple tabs in the
browser.
Process:
1.Process is a heavy weight process.
2.Process is a separate program that has
separate memory, data, resources etc.
3.Process are created using fork() method.
4.Context switch between the process is
time consuming.
Example:
Say, opening any browser (mozilla,
Chrome, IE). At this point new process will
start to execute.

Multiprocessing in OS
 Multiprocessing sometimes refers to
executing multiple processes (programs)
at the same time.
Multitasking :-
it is the process of executing several
task simultaneously

The process of executing multiple threads concurrently is known as
multithreading
Multithreading in Java
Let’s summarize the discussion in points:
1. The main purpose of multithreading is to provide concurrent
execution of two or more parts of a program to maximum utilize the
CPU time. A multithreaded program contains two or more parts that
can run concurrently. Each such part of a program called thread.
2. Threads are lightweight sub-processes, they share the common
memory space. In Multithreaded environment, programs that are
benefited from multithreading, utilize the maximum CPU time so that
the idle time can be kept to minimum.

A program (Process) is divided
into two or more subprograms
(process), which can be
implemented at the same time in
parallel/ concurrently
Example:- suppose we run a
program which include two
methods M1 and M2 these
methods are threads but run
concurrently
A Program
Method-1
Method-2
Multithreading :-

Multitasking
Process based Thread based
 Facebook
 Music Player
 Browser
Heavyweight
Own Memory
Address Space
MS-
Word
Home
Tab
Spelling
Check
Threads
Lightweight
Address Space
is share

Multitasking vs. Multithreading vs. Multiprocessing
vs. parallel processing
Multitasking: Ability to execute more than one task at the same
time is known as multitasking.
Multithreading: We already discussed about it. It is a process of
executing multiple threads simultaneously. Multithreading is also
known as Thread-based Multitasking.
Multiprocessing: It is same as multitasking, however in
multiprocessing more than one CPUs are involved. On the other
hand one CPU is involved in multitasking.
Parallel Processing: It refers to the utilization of multiple CPUs in a
single computer system.

Creating a thread in Java
There are two ways to create a thread in Java:
Thread in Java
By extending
Thread class
extends
Thread
implementing
Runnable
interface
Implements
Runnable

Every time a Java program starts up, one thread begins running
which is called as the main thread of the program because it is the
one that is executed when your program begins
When you implements Runnable , you can save a space for
your class to extend any other class in future or now.
Java doesn't support multiple inheritance, which means you can
only extend one class in Java so once you extended Thread class
you lost your chance and can not extend or inherit another class in Java
Thread Creation in Java
Main Thread
Deference B/w Extending and implementing runnable class

Before we begin with the programs(code) of creating threads,
let’s have a look at these methods of Thread class.
We have used few of these methods in the example below.
•getName(): It is used for Obtaining a thread’s name
•getPriority(): Obtain a thread’s priority
•isAlive(): Determine if a thread is still running
•join(): Wait for a thread to terminate
•run(): Entry point for the thread
•sleep(): suspend a thread for a period of time
•start(): start a thread by calling its run() method
METHODS OF THREAD CLASS

Method 1: Thread creation by extending Thread class
class MultithreadingDemo implements Runnable
{
public void run()
{
System.out.println("My thread is in running state.");
}
public static void main(String args[])
{
MultithreadingDemo obj=new MultithreadingDemo();
Thread objt1 = new Thread(obj);
objt1.start();
}
}
Output:
My thread is in running state.

Method 2: Thread creation by implementing Runnable Interface
class MultithreadingDemo implements Runnable
{
public void run()
{
System.out.println("My thread is in running state.");
}
public static void main(String args[])
{
MultithreadingDemo obj=new MultithreadingDemo();
Thread tobj =new Thread(obj);
tobj.start();
}
}
A Simple Example
Output:
My thread is in running state.

Advantages of Multithreading
 Enable programmers to do multiple things at one time
 Programmers can divided a long program into threads
and execute them parallel which will eventually increases
speed of program execution
 Improved performance and concurrency
 Simultaneous access of multiple applications

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Multithreading in-java

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