Multithreading

Introduction to Multithreading in Java

Multithreading is a core feature of Java that allows multiple threads to run concurrently within a program. A thread is the smallest unit of a process, and multithreading enables efficient utilization of CPU resources by executing multiple tasks simultaneously. This is particularly useful for applications that require parallel processing, such as gaming, web servers, or real-time systems.

Java provides built-in support for multithreading through the java.lang.Thread class and the java.util.concurrent package, making it easier to create and manage threads.

Creating Threads in Java

There are two primary ways to create threads in Java:

Extending the `Thread` Class:

Create a class that extends the Thread class.
Override the run() method to define the task to be executed by the thread.
Start the thread using the start() method.

class MyThread extends Thread {
public void run() {
        System.out.println("Thread is running: " + Thread.currentThread().getName());
}
}

public class ThreadExample {
public static void main(String[] args) {
        MyThread thread1 = new MyThread();
thread1.start(); // Starts the thread
}
}

Implementing the `Runnable` Interface:

Create a class that implements the Runnable interface.
Define the task in the run() method.
Pass the Runnable object to a Thread object and start the thread.

class MyRunnable implements Runnable {
public void run() {
        System.out.println("Thread is running: " + Thread.currentThread().getName());
}
}

public class RunnableExample {
public static void main(String[] args) {
        MyRunnable runnable = new MyRunnable();
Thread thread = new Thread(runnable);
thread.start(); // Starts the thread
}
}

*To Avoid Diamond problem, It is advisable to use Interface in place of Thread class.

Thread Lifecycle

A thread in Java goes through the following states:

New: The thread is created but not yet started.
Runnable: The thread is ready to run but waiting for CPU time.
Running: The thread is actively executing.
Blocked/Waiting: The thread is waiting for a resource or signal.
Terminated: The thread has completed execution.

Advantages of Multithreading

Concurrency: Multiple tasks can run simultaneously.
Resource Sharing: Threads share the same memory space, reducing overhead.
Improved Performance: Tasks are executed faster by utilizing CPU cores efficiently.

Challenges of Multithreading

Thread Interference: Multiple threads accessing shared resources can lead to data inconsistency.
Deadlocks: Threads waiting indefinitely for resources can cause a deadlock.
Complex Debugging: Multithreaded programs are harder to debug due to concurrent execution.

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