Threads and Multi-Threading: Operating system

Threads and Multi-Threading: Operating system

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Vikram
Vikram Singh
Assistant Manager - Content
Updated on Mar 29, 2024 17:39 IST

In any software system, there are always a variety of threads at work. These threads can be classified into two general types: user threads and kernel threads. User threads are created and controlled by the user application, while kernel threads are created and controlled by the operating system kernel. In this post, we’ll look closely at threads and multi-threading with their advantages and disadvantages.

 

What is a thread in an operating system?

The smallest unit of a process. Process can have one or more threads.

A thread is a sequence of code that runs within a process and keeps track of its location in memory so it can resume where it left off when it next gets called. It is a lightweight process doing the same task as a process. 

One process can have multiple threads. 

Let me make this thing clear to you. Like in the below fig, you can see a black wire. This black wire contains different blue, green, and red wires. All these three wires are doing different purposes at the same time. So take that black wire as a process and three different wires as threads. This is an example of multithreading which we will cover further in this article.

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Threads are a way that the operating system handles the multiple tasks that you might ask it to do at the same time. In an ideal world, the operating system would be able to do all of these tasks simultaneously, but that isn’t always possible. The running programs are all linked together, meaning they’re all running in parallel. This makes it possible for the programs to work together as a team, rather than working against each other.

One example is when you’re working with a lot of data. It can take a long time if you try to open the file in one step. By using threads, you can divide the data into small pieces and open them one at a time. This way, the program will be able to finish much more quickly.

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How to check the threads in your operating system?

  1. Open Task manager
  2. Select performance tab 
  3. Look for processes ad threads

In this, you can see that number of processes running is 158, and the number of threads running is 2261.

Else you can also check out the process name.

On clicking the process, you will see this window.-

You will find all the details like Thread ID, context switches, etc.

Kernel-Level Threads

Kernel-level threads are the lowest level of threads that can be created in an operating system. They are handled by the operating system. The kernel is not aware of user-level threads and manages them as though they had been single-threaded processes. These threads are slow in comparison to user-level threads.

Advantages of Kernel-Level Threads

  • If one kernel-level thread gets blocked no effect on other threads.
  • The kernel can schedule multiple threads simultaneously from the same process 
  • They are perfect for tasks requiring a lot of power or speed as they can easily access the resources. 

Disadvantages of Kernel-Level Threads

  • They are slow in comparison to user-level threads.
  • Context switching is slow.
  • Control is transferred from one thread to another within the same process and requires the mode switch to the kernel.

 For one, they’re not as portable as user-level threads, as they require more access to the system. They’re also not as safe as user-level threads, as they can cause more crashes and system instability.

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User-Level Threads

User-level threads are created by a process and are owned by that process. When the process terminates, the threads it created terminate with it. This type of threading is easy to use and is perfect for short-running tasks.

Advantages of User-Level Threads

  • Thread switching doesn’t require kernel-mode privileges.
  • It can run on any operating system.
  • In the user-level thread, scheduling is application-specific.
  • User-level threads are fast to create and manage.  

Disadvantages of User-Level Threads

  • User-level threads are that they are not very resilient. If the process hosting the threads crashes, the threads will die. This can be a significant problem if you rely on those threads to keep your application running.
  • These threads are not generally recommended for long-running tasks or applications. For those types of tasks, kernel-level threads are a better option.

Difference between thread and process

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What is Multi-Threading?

Multithreading is the process of executing multiple tasks simultaneously. In computer science, multithreading refers to a program running in parallel with another program. This means that the two programs are executing at the same time, on separate threads of execution. Multiple tasks can be executed simultaneously on separate cores of a processor or separate processors.

Example of Multi-Threading in real-life scenarios

  • If you’re trying to open a file in your program, you might want to be able to do it without waiting for the program that you’re running in the back.
  • If you are processing data in a database, you can use a thread to process the data cooperatively. In this scenario, the data is written to the database in parallel, and then the threads read the data back.
  • Downloading the file and viewing it simultaneously.
  • Video games are based on multithreading where graphics run in the background.

How Multi-Threading works in the operating system

Multithreading in operating systems is implemented through the use of threading libraries. These libraries provide the programmer with APIs that make it easy to create multithreaded programs. The threading library takes care of all the low-level coordination required to keep the threads running in a synchronized fashion. This synchronization is necessary

Advantages of Multi-Threading

  • Multithreading allows the CPU to execute multiple tasks simultaneously, which can boost performance.
  • Multithreading reduces the amount of time that is spent waiting for a task to finish.
  • Multithreading can help to improve the scalability of a program.
  • Interactive applications may allow a program to continue running even if part of it is blocked or is performing a lengthy operation, thereby increasing responsiveness.

Disadvantages of Multi-Threading 

  • Multithreading can be complex and challenging to implement.
  • Multithreading can increase the complexity of a program.
  • Multithreading can be error-prone.
  • Programmers must carefully design their code to utilize multithreading capabilities without introducing unwanted delays or fragmentation into their programs’ execution.

Conclusion

So, those are the different types of threads available in the Windows operating system. As you can see, they each have their unique purpose, so it’s essential to be familiar with them. Now that you know what they are, you can start using them to streamline your work processes and get things done more efficiently. In this article, we focussed on Threads and Multi-Threading with their real-life scenarios. For other blogs on the operating systems please stay tuned!!

Thanks for reading!!

About the Author
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Vikram Singh
Assistant Manager - Content

Vikram has a Postgraduate degree in Applied Mathematics, with a keen interest in Data Science and Machine Learning. He has experience of 2+ years in content creation in Mathematics, Statistics, Data Science, and Mac... Read Full Bio