In Java, multithreading is a powerful feature that allows concurrent execution of two or more threads for maximum utilization of CPU. Understanding the lifecycle and states of a thread is crucial for writing efficient multithreaded applications. In this blog, we’ll explore the various states a thread can be in and the transitions between these states.
In the context of programming, a thread is the smallest unit of execution within a process. A thread is a lightweight subprocess that can be managed independently by a scheduler. Each thread in a program operates within the context of a process, sharing the process’s resources such as memory and file handles, but it has its own execution stack and program counter.
Concurrency: Allows multiple tasks to be in progress within a single program. This is essential for performing tasks like handling user inputs, processing background tasks, and updating the user interface simultaneously.
Parallelism: In a multi-core processor environment, threads can run in parallel, thus making better use of CPU resources and improving the overall performance of the application.
Responsiveness: Threads can enhance the responsiveness of an application. For instance, in a graphical user interface (GUI) application, a dedicated thread can be used to handle user inputs while other threads handle background tasks. This ensures that the application remains responsive to user actions.
Resource Sharing: Threads within the same process share memory and resources, which allows them to communicate and share information more efficiently than separate processes. This sharing reduces the overhead of memory usage and improves performance.
Efficient Use of Resources: Threads can be used to perform multiple tasks simultaneously within the same program, thereby making efficient use of system resources. For example, in a web server, multiple threads can handle multiple client requests concurrently.
Extending the Thread class
public class MyThread extends Thread {
@Override
public void run() {
// Code to be executed by the thread
for (int i = 1; i <= 5; i++) {
System.out.println("Thread is running: " + i);
try {
Thread.sleep(500); // Simulate some work with sleep
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("Thread execution completed");
}
public static void main(String[] args) {
MyThread thread = new MyThread();
thread.start(); // Start the thread
}
}Output:
Thread is running: 1 Thread is running: 2 Thread is running: 3 Thread is running: 4 Thread is running: 5 Thread execution completed
Explanation:
Key Points:
Implementing the Runnable Interface Runnable Interface
public class MyRunnable implements Runnable {
@Override
public void run() {
// Code to be executed by the thread
for (int i = 1; i <= 5; i++) {
System.out.println("Thread is running: " + i);
try {
Thread.sleep(500); // Simulate some work with sleep
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("Thread execution completed");
}
public static void main(String[] args) {
MyRunnable myRunnable = new MyRunnable();
Thread thread = new Thread(myRunnable);
thread.start(); // Start the thread
}
}Output:
Thread is running: 1 Thread is running: 2 Thread is running: 3 Thread is running: 4 Thread is running: 5 Thread execution completed
Explanation:
Key Points:
In Java, threads go through several distinct states from their creation to their termination. Understanding these states is crucial for effectively managing multithreaded applications. Below, we introduce the phases of a thread’s lifecycle and provide an illustrative diagram for better comprehension.
Thread thread = new Thread(new MyRunnable());
Runnable: A thread that is ready to run and waiting for CPU cycles.
thread.start();
Blocked: A thread that is blocked waiting for a monitor lock. It occurs while Entering a synchronized block or method when another thread holds the lock.
synchronized (lock) {
// thread code
}Waiting: A thread that is indefinitely paused, awaiting a specific action from another thread. You can enter this state by calling wait() on an object.
synchronized (lock) {
lock.wait();
}Timed Waiting: A thread that is waiting for another thread to perform an action within a time limit. You can enter this state by Calling sleep(), wait(long timeout), join(long timeout), LockSupport.parkNanos(), or LockSupport.parkUntil().
Thread.sleep(1000);
Terminated: A thread that has completed its execution.It occurs When the run() method finishes execution.
public void run() {
// thread execution code
System.out.println("Thread is running");
}Example 1:
public class ThreadLifecycleExample {
public static void main(String[] args) {
Thread thread = new Thread(new MyRunnable());
System.out.println(thread.getState()); // NEW
thread.start();
System.out.println(thread.getState());
// RUNNABLE
try {
thread.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(thread.getState());
// TERMINATED
}
}
class MyRunnable implements Runnable {
@Override
public void run() {
System.out.println("Thread is running");
}
}Output:
NEW RUNNABLE Thread is running TERMINATED
Example 2: Synchronization and State Transitions
public class ThreadSyncExample {
private static final Object lock = new Object();
public static void main(String[] args) {
Thread thread1 = new Thread(new SyncTask());
Thread thread2 = new Thread(new SyncTask());
thread1.start();
thread2.start();
}
static class SyncTask implements Runnable {
@Override
public void run() {
synchronized (lock) {
System.out.println(Thread.currentThread().getName() + " has acquired the lock");
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName() + " is releasing the lock");
}
}
}
}Output:
Thread-0 has acquired the lock Thread-0 is releasing the lock Thread-1 has acquired the lock Thread-1 is releasing the lock
In this example, we will create a class Counter with a method increment() that increments a shared counter. We will use a synchronized block to ensure that the counter is incremented safely by multiple threads.
Example: Synchronization with a Shared Counter
public class SynchronizedExample {
public static void main(String[] args) {
Counter counter = new Counter();
Thread thread1 = new Thread(new CounterTask(counter));
Thread thread2 = new Thread(new CounterTask(counter));
thread1.start();
thread2.start();
try {
thread1.join();
thread2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("Final counter value: " + counter.getCount());
}
}
class Counter {
private int count = 0;
private final Object lock = new Object();
public void increment() {
synchronized (lock) {
// thread code
count++;
System.out.println(Thread.currentThread().getName() + " incremented count to: " + count);
}
}
public int getCount() {
return count;
}
}
class CounterTask implements Runnable {
private final Counter counter;
public CounterTask(Counter counter) {
this.counter = counter;
}
@Override
public void run() {
for (int i = 0; i < 10; i++) {
counter.increment();
try {
Thread.sleep(100); // To simulate some work being done
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}Output:
Thread-0 incremented count to: 1 Thread-1 incremented count to: 2 Thread-0 incremented count to: 3 Thread-1 incremented count to: 4 Thread-0 incremented count to: 5 Thread-1 incremented count to: 6 Thread-1 incremented count to: 7 Thread-0 incremented count to: 8 Thread-1 incremented count to: 9 Thread-0 incremented count to: 10 Thread-1 incremented count to: 11 Thread-0 incremented count to: 12 Thread-1 incremented count to: 13 Thread-0 incremented count to: 14 Thread-1 incremented count to: 15 Thread-0 incremented count to: 16 Thread-1 incremented count to: 17 Thread-0 incremented count to: 18 Thread-1 incremented count to: 19 Thread-0 incremented count to: 20 Final counter value: 20
Explanation:
🔹Counter Class
Fields:
Count: The shared counter variable.
Lock: An object used for synchronization.
Methods:
increment(): This method increments the counter. The method is synchronized using the lock object to ensure that only one thread can execute the code inside the synchronized block at a time.
getCount(): Returns the current value of the counter.
🔹CounterTask Class
Implements the Runnable interface and contains the logic to call the increment() method of the Counter class multiple times.
🔹Main Method
Key Points:
This example demonstrates how synchronization can be used to control access to shared resources in a multithreaded environment, preventing race conditions and ensuring data consistency.
Mastering Java thread lifecycle and states is essential for efficient multithreaded programming. This knowledge enables developers to create responsive applications that optimize system resources, especially in multi-core environments. Understanding thread states and transitions helps manage thread behavior effectively, improving performance and minimizing common concurrency issues like race conditions and deadlocks.
In the ever-evolving landscape of Java development, proficiency in thread management is a crucial skill. Proper implementation of thread lifecycle management and synchronization techniques allows developers to build scalable, efficient applications capable of handling complex tasks and high user loads. As software systems grow more complex and distributed, expertise in Java’s threading model remains vital for creating high-performance, concurrent applications across various domains.
The team at Mindbowser was highly professional, patient, and collaborative throughout our engagement. They struck the right balance between offering guidance and taking direction, which made the development process smooth. Although our project wasn’t related to healthcare, we clearly benefited...
Founder, Texas Ranch Security
Mindbowser played a crucial role in helping us bring everything together into a unified, cohesive product. Their commitment to industry-standard coding practices made an enormous difference, allowing developers to seamlessly transition in and out of the project without any confusion....
CEO, MarketsAI
I'm thrilled to be partnering with Mindbowser on our journey with TravelRite. The collaboration has been exceptional, and I’m truly grateful for the dedication and expertise the team has brought to the development process. Their commitment to our mission is...
Founder & CEO, TravelRite
The Mindbowser team's professionalism consistently impressed me. Their commitment to quality shone through in every aspect of the project. They truly went the extra mile, ensuring they understood our needs perfectly and were always willing to invest the time to...
CTO, New Day Therapeutics
I collaborated with Mindbowser for several years on a complex SaaS platform project. They took over a partially completed project and successfully transformed it into a fully functional and robust platform. Throughout the entire process, the quality of their work...
President, E.B. Carlson
Mindbowser and team are professional, talented and very responsive. They got us through a challenging situation with our IOT product successfully. They will be our go to dev team going forward.
Founder, Cascada
Amazing team to work with. Very responsive and very skilled in both front and backend engineering. Looking forward to our next project together.
Co-Founder, Emerge
The team is great to work with. Very professional, on task, and efficient.
Founder, PeriopMD
I can not express enough how pleased we are with the whole team. From the first call and meeting, they took our vision and ran with it. Communication was easy and everyone was flexible to our schedule. I’m excited to...
Founder, Seeke
We had very close go live timeline and Mindbowser team got us live a month before.
CEO, BuyNow WorldWide
If you want a team of great developers, I recommend them for the next project.
Founder, Teach Reach
Mindbowser built both iOS and Android apps for Mindworks, that have stood the test of time. 5 years later they still function quite beautifully. Their team always met their objectives and I'm very happy with the end result. Thank you!
Founder, Mindworks
Mindbowser has delivered a much better quality product than our previous tech vendors. Our product is stable and passed Well Architected Framework Review from AWS.
CEO, PurpleAnt
I am happy to share that we got USD 10k in cloud credits courtesy of our friends at Mindbowser. Thank you Pravin and Ayush, this means a lot to us.
CTO, Shortlist
Mindbowser is one of the reasons that our app is successful. These guys have been a great team.
Founder & CEO, MangoMirror
Kudos for all your hard work and diligence on the Telehealth platform project. You made it possible.
CEO, ThriveHealth
Mindbowser helped us build an awesome iOS app to bring balance to people’s lives.
CEO, SMILINGMIND
They were a very responsive team! Extremely easy to communicate and work with!
Founder & CEO, TotTech
We’ve had very little-to-no hiccups at all—it’s been a really pleasurable experience.
Co-Founder, TEAM8s
Mindbowser was very helpful with explaining the development process and started quickly on the project.
Executive Director of Product Development, Innovation Lab
The greatest benefit we got from Mindbowser is the expertise. Their team has developed apps in all different industries with all types of social proofs.
Co-Founder, Vesica
Mindbowser is professional, efficient and thorough.
Consultant, XPRIZE
Very committed, they create beautiful apps and are very benevolent. They have brilliant Ideas.
Founder, S.T.A.R.S of Wellness
Mindbowser was great; they listened to us a lot and helped us hone in on the actual idea of the app. They had put together fantastic wireframes for us.
Co-Founder, Flat Earth
Ayush was responsive and paired me with the best team member possible, to complete my complex vision and project. Could not be happier.
Founder, Child Life On Call
The team from Mindbowser stayed on task, asked the right questions, and completed the required tasks in a timely fashion! Strong work team!
CEO, SDOH2Health LLC
Mindbowser was easy to work with and hit the ground running, immediately feeling like part of our team.
CEO, Stealth Startup
Mindbowser was an excellent partner in developing my fitness app. They were patient, attentive, & understood my business needs. The end product exceeded my expectations. Thrilled to share it globally.
Owner, Phalanx
Mindbowser's expertise in tech, process & mobile development made them our choice for our app. The team was dedicated to the process & delivered high-quality features on time. They also gave valuable industry advice. Highly recommend them for app development...
Co-Founder, Fox&Fork
