multithreading in Java that you need to know

2 years ago

8 minutes

Using high-quality can result in faster execution when running an application in the real world. However, it is important to note that solely relying on processor speed is insufficient for achieving optimal application performance. Employing multithreading is an excellent approach to developing an application that is efficient in terms of performance.

What does Multithreading mean?

Multithreading refers to a programming concept where an application can generate several smaller tasks to run simultaneously. When using a computer, it can run multiple applications and distribute processing power among them. A basic program runs sequentially, with code statements executing one after another, thus being referred to as a single-threaded application. However, if the programming language enables the creation of multiple threads and sends them to the operating system for parallel execution, it is categorized as multithreading.

Thread management compared to process management

When discussing multithreading, the number of processor cores on the machine, whether it be 2 or 16, is irrelevant. Our task is to develop a multithreaded application and leave the task of allocating and executing threads to the operating system. In other words, multithreading and multiprocessing are unrelated.

How does Java provide support for multithreading?

Java provides excellent support for developing applications that can run concurrently using multiple threads. This is achieved in Java through the Thread class, which allows us to create a lightweight process that performs various tasks. We can have multiple threads within our program and initiate their execution. The Java runtime system handles the creation of machine-level instructions and collaborates with the operating system to execute them simultaneously.

What are the various categories of threads?

An application consists of two types of threads: user threads and daemon threads. Upon starting an application, the first thread created is the main user thread. We have the option to create multiple user threads and daemon threads. Once all the user threads have completed their execution, the JVM will terminate the program.

What does Thread Priority mean?

When a thread is created, we have the ability to designate its priority. While it is possible to assign various priorities to different threads, there is no assurance that a thread with higher priority will necessarily be executed before a thread with lower priority. The responsibility of controlling a thread’s execution lies with the thread scheduler, which is a component of the operating system. The Java Virtual Machine (JVM) does not have any authority over the execution of a thread once it has been started.

What is the process of creating threads in Java?

There are two ways to create Threads: one is by implementing the Runnable interface, and the other is by extending the Thread Class.

Thread t = new Thread(new Runnable(){
    @Override
    public void run() {
    }
});

Here is a concise way to create a new Thread – instead of using an anonymous class, we can employ a lambda expression, making the code much shorter.

Runnable runnable = () -> System.out.println("Hello");

After we have created a Thread, we need to initiate its execution by invoking the start() method.

runnable.start();

I have composed numerous articles elucidating the principles of multithreading in Java. You can go through them in a sequential manner to acquire comprehensive knowledge on multithreading including its application in real-life scenarios, the life cycle of threads, thread pooling, and so on.

1. Java Thread and Runnable serve the same purpose

In this introductory post, we delve into the Thread class and Runnable interface, exploring their distinctions and benefits. We examine the disparity between Threads and Processes while also elaborating on the process of creating Threads through the utilization of the Runnable interface and Thread class. Additionally, this post presents a thorough comparison between the Thread class and the Runnable interface.

2. Sleeping in a Java Thread

Does Thread.sleep() in Java pause the execution of the current thread? We will be using Thread.sleep() a lot in upcoming posts, so it’s important to understand how it functions and if it is reliable.

3. Joining Java Threads

At times, it becomes necessary to wait for the completion of other threads before moving forward. This objective can be accomplished by utilizing the join method of Threads. Gain an understanding of how this method operates and its appropriate usage timing.

4. States of Java Threads

It is crucial to comprehend various thread states. Gain knowledge about the transformation of a thread’s state and how the thread scheduler of the operating system modifies it.

5. Usage of wait, notify, and notifyAll in Java threads.

The Java Object class has three methods that provide information about the locking status of a resource. Understand the usage of these methods in a basic Wait-Notify implementation through an illustrative example.

6. Ensuring the safety of threads and synchronization between them

Threads can cause data corruption by sharing Object resources due to the lack of atomicity in these operations. To ensure thread-safety in Java, there are several methods you can use. This post provides insights into synchronization, synchronized methods, and synchronized blocks and their appropriate usage.

7. An exception in the main thread occurred in Java.

The first thread is generated by the JVM through the utilization of the main method. This article provides an explanation for several familiar exceptions encountered in our daily lives, delving into their underlying causes and offering solutions for resolving them.

Thread safety in a singleton class is about ensuring that it can be accessed and modified by multiple threads in a safe and synchronized manner.

This article covers the fundamentals of developing a Singleton class. It explores the potential concerns related to thread safety in various implementations and provides solutions for ensuring thread safety in a Singleton class.

The Daemon Thread in Java refers to a threading concept in the Java programming language.

An uncomplicated article that elucidates daemon threads and their creation in Java.

10. Localizing Java Threads

If we desire to create thread-local variables at the class level, we can utilize Java’s ThreadLocal utility class, which allows threads to possess their own variables. To gain insights into implementing ThreadLocal variables in a Java program, continue reading.

11. A dump of Java threads.

A Java thread dump offers details about the current thread, and it serves as a valuable resource for analyzing performance problems within an application. By generating a thread dump, you can identify and resolve situations involving deadlocks. This article provides a variety of approaches for creating thread dumps in Java.

12. The procedure for examining deadlock situations in Java

A deadlock occurs when multiple threads are in a state of waiting for each other to release resources, resulting in a cycle of dependency. This article examines how deadlock can arise in a Java program, explores how a Thread dump can be used to identify deadlock, and offers recommendations on implementing best practices to prevent deadlock in Java programs.

13. Java Timer Thread – A thread in Java used for timing purposes.

This article provides an explanation on utilizing the Java Timer and TimerTask classes to create scheduled jobs, including a sample program demonstrating its usage, as well as instructions for canceling the timer.

The issue of the Java Producer Consumer Problem in question 14.

In earlier versions of Java, the producer-consumer problem could be resolved by utilizing the wait() and notify() methods. However, with the implementation of BlockingQueue, this process has become much simpler. Find out how we can utilize BlockingQueue in Java to effectively solve the producer-consumer problem.

One possibility would be:
15. ThreadPool in Java

A Java Thread Pool refers to a group of worker threads ready to handle tasks. The Executor framework introduced in Java 5 simplifies the process of creating a thread pool. Executors and ThreadPoolExecutor classes can be utilized to establish and control a thread pool.

One possible paraphrase could be:
“Java’s Callable Future in the 16th edition.”

In certain situations, we may desire our Thread to provide us with values that we can utilize. In such cases, Java 5 Callable can be employed, resembling the Runnable interface. The Executor framework can execute Callable tasks for us.

Example of a FutureTask in Java.

The FutureTask class is a concrete base class that directly implements the Future interface. It is employed alongside Callable implementation and Executors for asynchronous processing. This class offers methods to examine the status of the task and deliver the resulting value to the calling program after its completion. It proves useful when there is a need to customize certain aspects of the implementation methods provided by the Future interface.

In summary.

It would not have been possible to cover everything about multithreading in a single post since it is a vast subject. However, if you read the previous posts in order, you will gain a comprehensive understanding of multithreading in Java.