What is Multithreading in Java?

Multithreading is one of the more important concepts in Object Oriented Programming and also one of the key features of Java. It can be quite a confusing topic and as such this article would provide much-needed clarity on this topic.

What are Threads?

A thread may be a sequence of such directions among a program that may be dead severally of alternative code. It is lightweight and therefore the smallest unit of execution in a process.A Process can be best described as a program in execution. It has its own address space.

Threads should not be confused with a Process as a thread is contained in a process hence a process can be made up of several threads. Therefore several threads in a process share similar resources while several processes in an operating system do not.

What is Multithreading?

Multithreading in Java is a process of executing two or more threads simultaneously to maximum utilization of the CPU. Multithreaded applications execute two or more threads that run concurrently. Hence, it’s additionally referred to as Concurrency in Java. Every thread runs parallel to the opposite. Multiple threads do not allot separate memory areas, thus they save memory. Also, context change between threads takes less time.

Differences between Multithreading and Multiprocessing

Key DIFFERENCES:

• A multiprocessing system has more than two processors whereas Multithreading is a program execution technique that allows a single process to have multiple code segments.
• Multiprocessing improves the reliability of the system while in the multithreading process, each thread runs parallel to the other.
• Multiprocessing helps you to increase computing power whereas multithreading helps you create computing threads of a single process
• In Multiprocessing, the creation of a process is slow and resource-specific whereas, in Multiprogramming, the creation of a thread is economical in time and resource.
• Multithreading avoids pickling, whereas Multiprocessing relies on pickling objects in memory to send to other processes.
• Multiprocessing system takes less time whereas for job processing a moderate amount of time is taken.

Multithreading in action

 // Main Class

    class app {

        public static void main(String[] args) {

            int n = 9; // Number of threads

            for (int i = 0; i < n; i++) {

                MultithreadingDemo object

                        = new MultithreadingDemo();

                object.start();

            }

        }

    }

    class MultithreadingDemo extends Thread {

        public void run()

        {

            try {

                // Display the thread that is running

                System.out.println(

                        "Thread " + Thread.currentThread().getId()

                                + " is running");

            }

            catch (Exception e) {

                // Throwing an exception

                System.out.println("Exception is caught");        

Advantages of Multithreading

Below are some pros of multithreading

• Threads share the same address space
• Threads are lightweight which has a low memory footprint
• The cost of communication between threads is low.
• Access to memory state from another context is easier
• It allows you to make responsive UIs easily
• An ideal option for I/O-bound applications
• Takes lesser time to change between two threads inside the shared memory and time to terminate
• Threads are faster to start than processes and also faster in task-switching.
• All Threads share a process memory pool that is very beneficial.
• Takes lesser time to create a new thread in the existing process than a new process

Disadvantages of Multithreading

Some common disadvantages associated with Multithreading include;

• Increased difficulty in testing
• Increased difficulty in writing code as multithreaded applications are not easy to write
• The tendency for the occurrence of deadlocks
• Difficulty in debugging