Python Multi Threading - Introduction and Multi Tasking

Multi Threading is introduced under the topic Multi Tasking.

Before understanding Multi Threading, first we should understand what Multi Tasking means.

Multi Threading allows different independent parts of the same program to perform their work concurrently.

Multi Tasking means executing several tasks simultaneously.

Simple Definition:

Executing several tasks simultaneously is called Multi Tasking.

For example, while working on a computer, we may perform several activities such as:

• Writing a Python program
• Listening to music
• Downloading files

These activities can execute simultaneously.

There are two types of Multi Tasking:

1. Process Based Multi Tasking
2. Thread Based Multi Tasking

                 Multi Tasking
                      │
          ┌───────────┴───────────┐
          │                       │
          ▼                       ▼
   Process Based             Thread Based
   Multi Tasking             Multi Tasking

Both approaches allow multiple tasks to make progress, but they differ in how those tasks are organized.

Process Based Multi Tasking means executing several tasks simultaneously where each task is a separate independent process.

Definition:

Executing several tasks simultaneously where each task is a separate independent process is called Process Based Multi Tasking.

Here, every task runs as an independent process.

Consider the following example.

While typing a Python program in an editor, we can simultaneously:

• Listen to MP3 songs
• Download files from the Internet

Therefore, the computer may be performing:

Task 1 → Python Editor

Task 2 → MP3 Player

Task 3 → Internet Download

All these tasks execute simultaneously and independently.

Hence, this is an example of Process Based Multi Tasking.

                  Operating System
                         │
            ┌────────────┼────────────┐
            │            │            │
            ▼            ▼            ▼
      Python Editor   MP3 Player   Internet Download
            │            │            │
            ▼            ▼            ▼
        Process 1     Process 2     Process 3

All are separate independent processes.

Process Based Multi Tasking is best suitable at the Operating System level.

An Operating System can execute and manage several independent applications or processes.

Examples include:

• Python Editor
• Music Player
• Browser
• File Downloader

Each application can run as a separate process.

Thread Based Multi Tasking means executing several tasks simultaneously where each task is a separate independent part of the same program.

Each independent part is called a Thread.

Definition:

Executing several tasks simultaneously where each task is a separate independent part of the same program is called Thread Based Multi Tasking, and each independent part is called a Thread.

A Thread represents an independent path of execution inside a program.

A single program can contain multiple threads.

Program
   │
   ├──── Thread 1
   │
   ├──── Thread 2
   │
   └──── Thread 3

All these threads belong to the same program.

                     Program
                        │
             ┌──────────┼──────────┐
             │          │          │
             ▼          ▼          ▼
          Thread 1   Thread 2   Thread 3
             │          │          │
             └──────────┴──────────┘
                        │
                        ▼
               Same Python Program

All threads belong to the same program.

Thread Based Multi Tasking is best suitable at the Programmatic level.

It is useful when one program contains several independent jobs that can make progress concurrently.

One Program
     │
     ├── Job 1 → Thread 1
     ├── Job 2 → Thread 2
     └── Job 3 → Thread 3

Feature	Process Based Multi Tasking	Thread Based Multi Tasking
Task	Separate independent process	Separate independent part of the same program
Execution Unit	Process	Thread
Program Relationship	Tasks can belong to different programs	Threads belong to the same program
Best Suitable For	Operating System level	Programmatic level
Example	Editor + MP3 Player + Download	Multiple independent jobs inside one program

Whether it is:

• Process Based Multi Tasking
• Thread Based Multi Tasking

the main advantage of Multi Tasking is to improve the performance of the system by reducing response time.

Multiple Independent Tasks
          │
          ▼
Execute Concurrently
          │
          ▼
Better Resource Utilization
          │
          ▼
Reduced Response Time

The main application areas of Multi Threading are:

1. To implement Multimedia Graphics
2. To develop Animations
3. To develop Video Games
4. To develop Web and Application Servers
5. etc.

These types of applications can contain multiple independent jobs that need to make progress concurrently.

Wherever a group of independent jobs is available, it is highly recommended to execute them simultaneously instead of executing them one by one when concurrent execution is appropriate.

For such cases, we can go for Multi Threading.

Independent Jobs
      │
      ├── Job 1
      ├── Job 2
      └── Job 3
      │
      ▼
Execute Using Multiple Threads
      │
      ▼
Concurrent Execution

Python provides an inbuilt module called:

threading

This module provides support for developing and managing threads.

Hence, developing multithreaded programs is convenient in Python.

To use the module, we can import it:

import threading

Every Python program by default contains one thread.

This default thread is called:

MainThread

Simple Definition:

The default thread that starts the execution of a Python program is called the Main Thread.

Even if we do not explicitly create any additional thread, the Python program already executes using the Main Thread.

Python Program Starts
        │
        ▼
   MainThread
        │
        ▼
Execute Program Statements

Step 1: Import the threading Module

import threading

The threading module provides support for creating and managing threads.

---

Step 2: Get the Current Executing Thread

threading.current_thread()

current_thread() returns the currently executing Thread object.

In this program, we have not created any child thread.

Therefore, the current executing thread is the default Main Thread.

---

Step 3: Get the Thread Name

.name

The name property of a Thread object returns the name of that thread.

The default thread name is:

MainThread

---

Step 4: Display the Thread Name

print("Current Executing Thread:",
      threading.current_thread().name)

Therefore, the output is:

Current Executing Thread: MainThread

Since every Python program starts with one default thread, its name is MainThread.

The current_thread() function returns the Thread object representing the thread that is currently executing the statement.

Syntax:

threading.current_thread()

In our example:

threading.current_thread()

returns the object representing:

MainThread

The name property returns the name assigned to a Thread object.

Syntax:

thread_object.name

Example:

threading.current_thread().name

Result:

MainThread

Therefore:

current_thread()
      │
      ▼
Current Thread Object
      │
      ▼
name property
      │
      ▼
"MainThread"

Start Python Program
        │
        ▼
Python Starts Default Thread
        │
        ▼
    MainThread
        │
        ▼
Import threading Module
        │
        ▼
Call current_thread()
        │
        ▼
Returns Current Thread Object
        │
        ▼
Read the name property
        │
        ▼
Returns "MainThread"
        │
        ▼
Display Output
        │
        ▼
Current Executing Thread:
MainThread

Process Based Multi Tasking

Operating System
      │
      ├── Process 1
      ├── Process 2
      └── Process 3


Thread Based Multi Tasking

Single Program
      │
      ├── Thread 1
      ├── Thread 2
      └── Thread 3

The major conceptual difference is that process-based tasks are separate processes, whereas thread-based tasks are independent execution paths inside the same program.

Topic	Description
Multi Tasking	Executing several tasks simultaneously.
Types of Multi Tasking	Process Based and Thread Based.
Process Based Multi Tasking	Each task is a separate independent process.
Best Suitable Level for Process Based	Operating System level.
Thread Based Multi Tasking	Each task is a separate independent part of the same program.
Thread	An independent part or execution path of the same program.
Best Suitable Level for Thread Based	Programmatic level.
Main Advantage	Improves performance by reducing response time.
Multi Threading Applications	Multimedia Graphics, Animations, Video Games, Web Servers and Application Servers.
Python Module	threading
Default Thread	MainThread
current_thread()	Returns the currently executing Thread object.
name property	Returns the name of the Thread object.

1. Executing several tasks simultaneously is called Multi Tasking.
2. There are two types of Multi Tasking:
   • Process Based Multi Tasking
   • Thread Based Multi Tasking
3. In Process Based Multi Tasking, each task is a separate independent process.
4. Process Based Multi Tasking is best suitable at the Operating System level.
5. Typing a Python program while listening to MP3 songs and downloading files is an example of Process Based Multi Tasking.
6. In Thread Based Multi Tasking, each task is a separate independent part of the same program.
7. Each independent execution part is called a Thread.
8. Thread Based Multi Tasking is best suitable at the Programmatic level.
9. The main advantage of Multi Tasking is to improve system performance by reducing response time.
10. Multi Threading is commonly used for Multimedia Graphics, Animations, Video Games, Web Servers and Application Servers.
11. When a group of independent jobs is available and concurrent execution is appropriate, Multi Threading can be used instead of executing every job one by one.
12. Python provides the built-in threading module for thread-related programming.
13. Every Python program starts with one default thread.
14. The default thread is called MainThread.
15. current_thread() returns the currently executing Thread object.
16. name property returns the name of a thread.