Multithreading is a function of the CPU that permits multiple threads to run independently while sharing the same process resources. A thread is a conscience sequence of instructions that may run in the same parent process as other threads.
Multithreading allows many parts of a program to run simultaneously. These parts are referred to as threads, and they are lightweight processes that are available within the process. As a result, multithreading increases CPU utilization through multitasking. In multithreading, a computer may execute and process multiple tasks simultaneously.
Multithreading needs a detailed understanding of these two terms: process and thread. A process is a running program, and a process can also be subdivided into independent units called threads.
Below are the explanation of some examples of MultiThreading
Multiple threads run behind the scenes in most of the applications you use regularly. At any given time, you may have numerous tabs open in the system and every tab displaying different types of content. Many threads of execution are used to display animations, load content, play a video, etc.
A word processor is another instance of a multithreaded program with which you are all familiar. Multiple threads are used to show the content, asynchronously check content's spelling and grammar, and generate a PDF version of content while typing. These are all happening simultaneously, with independent threads doing these tasks internally.
Below are the advantages listed for Multithreading:
Various benefits of multithreading in the operating system are as follows:
Multithreading in an interactive application enables a program to continue running even if a section is blocked or executing a lengthy process, increasing user responsiveness.
A server in a non-multithreading environment listens to a port for a request, processes the request, and then resumes listening for another request. Other users are made to wait unnecessarily because of the time it takes to execute a request. Instead, a better approach will be to pass the request to a worker thread while listening on a port.
For instance, a multithreaded web browser permits the user interaction in one thread while a video is loading in another thread. As a result, instead of waiting for the entire web page to load, the user can continue viewing a section of a web page.
2. Resource Sharing
Processes can only share the resources only via two techniques such as:
- Message Passing
- Shared Memory
The programmer must explicitly structure such strategies. On the other hand, by default, threads share the memory and resources of the process they belong to.
The advantage of sharing code and data is that it permits an app to execute multiple code threads in the same address space.
Allocating memory and resources for process creation is an expensive procedure because it is a time and space-consuming task.
Because threads share a memory with the process to which they belong, establishing and context switching threads is more cost-effective. In general, generating and managing processes takes far more time than threads.
The advantages of multi-programming become much more apparent in the case of multiprocessor architecture, when threads may execute in parallel on many processors. When there is just one thread, it is impossible to break the processes into smaller jobs performed by different processors.
A single-threaded process could only run on one processor, despite the number of processors available. Multithreading on multiple CPU machines increases parallelism.
5. Better Communication
Thread synchronization functions could be used to improve inter-process communication. Moreover, sharing huge amounts of data across multiple threads of execution inside the same address space provides extremely high-bandwidth, low-latency communication across various tasks within an application.
6. Utilization of multiprocessor architecture
The advantages of multithreading might be considerably amplified in a multiprocessor architecture, where every thread could execute in parallel on a distinct processor.
A single-threaded task could only run on one of them, no matter how many CPUs are available. On a multi-CPU machine, multithreading enhances concurrency.
The CPU switches among threads so quickly in single-processor architecture that it creates the illusion of parallelism, but only one thread is running at a particular time.
7. Minimized system resource usage
Threads have a minimal influence on the system's resources. The overhead of creating, maintaining, and managing threads is lower than a general process.
Disadvantages of Multithreading
Here, you will learn the disadvantages of multithreading. There are various disadvantages of multithreading in the operating system, and some of the disadvantages are as follows:
- It needs more careful synchronization.
- It can consume a large space of stocks of blocked threads.
- It needs support for thread or process.
- If a parent process has several threads for proper process functioning, the child processes should also be multithreaded because they may be required.
- It imposes context switching overhead.
apart from above below are some mentioned multithreading programming advantages:
- Multithreading allows an application/program to be always reactive for input, even already running with some background tasks
- Multithreading allows the faster execution of tasks, as threads execute independently.
- Multithreading provides better utilization of cache memory as threads share the common memory resources.
- Multithreading reduces the number of the required server as one server can execute multiple threads at a time.