Key Difference – Multithreading vs Multitasking
 

Multithreading and Multitasking look similar but they are two different concepts. A computer performs many tasks simultaneously. Multithreading and Multitasking both relate to computer performance. The key difference between multithreading and multitasking is that in multithreading, multiple threads are executing in a process concurrently and, in multitasking, multiple processes are running concurrently. This article discusses the difference between multithreading and multitasking.

CONTENTS

1. Overview and Key Difference
2. What is Multithreading
3. What is Multitasking
4. Similarities Between Multithreading and Multitasking
5. Side by Side Comparison – Multithreading vs Multitasking in Tabular Form
6. Summary

What is Multithreading?

A computer system performs a number of tasks simultaneously. A task can be known as a process. It is a program in execution. Creating processes for each task is not efficient. It can consume many resources. To avoid that, a process can be divided into multiple sub-processes and the tasks can be executed using those sub-processes. One sub-process is a unit of the process. That unit is known as a thread. In multithreading, a process is divided into multiple threads and those threads are executing parallely at the same time.

There are two types of threaded applications named as, single threaded applications and multi-threaded applications. When there is one thread in a process, that is known as single threaded and when multiple threads are running in the process, it is called multithreaded application. Multithreading is useful to run several tasks at the same time. Bellow example shows a multithreaded process. T1, T2, T3 are threads.

Threads can also be categorized into two types. They are User threads and Kernel threads. The Kernel does not support user threads. Kernel threads are supported and managed by the kernel. There are three Multithreading models. There are named as Many-To-One model, One-To-One model, and Many-To-Many model. Bellow diagrams illustrate the threading models. ‘U’ denotes a User thread and ‘K’ denotes a kernel thread.

Many-To-One Model

In Many-To-One model, many user threads are mapped into single kernel thread.

Figure 02: Many-To-One Model

One-To-One Model

In one to one model, each user thread is mapped to a separate kernel thread.

Figure 03: One-To-One Model

Many-To-Many Model

In many of many models, multiplexes many user-level threads to smaller or equal number of kernel threads.

Figure 04: Many-To-Many Model

Multithreading provides several advantages. Threads are useful in inter-process communication. They also improve responsiveness. It is not necessary to allocate resources to each thread separately so, using threads are economical. If one thread fails, that will not affect the whole process. Threads are light-weight and consume a minimum amount of resources compared with a process.

What is Multitasking?

The computer can perform different tasks at the same time. For example, a browser, Word application, PowerPoint application, calculator application all can run at the same time. So, the computer is performing multiple tasks or multiple processes at the same time. It is called as Multitasking. Even though the computer can perform multiple tasks at the same time, there is a specific number of tasks which can be performed at a time.

Figure 05: Multitasking

Running many processes might decrease the computing speed because it requires more resources. Multitasking increases the productivity because multiple programs are running simultaneously. It is also easy for the user to notice an update immediately. 

What is the Similarity Between Multithreading and Multitasking?

• Both methods can affect the system performance.

What is the Difference Between Multithreading and Multitasking?

Summary – Multithreading vs Multitasking

Multithreading and Multiprocessing execute threads and processes at the same time. The difference between Multithreading and Multitasking is that in multithreading, multiple threads in a process are executing concurrently and in multitasking, multiple processes are running concurrently. Even though the terms look similar, they are different concepts. However, both these are main concepts in Computer Science. 

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Reference:

1.“What is Multitasking?” Computer Hope, 30 Oct. 2017. Available here
2.Point, Tutorials. “Operating System – Multi-Threading.”, Tutorials Point, 15 Aug. 2017. Available here 

Image Courtesy:

1.’Multitasking-os’By Jeff Meisel – Meisel, J. Task Parallelism, Connexions Web site.  Nov 28, 2007. (CC BY 2.0) via Commons Wikimedia

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