Java Executors newVirtualThreadPerTaskExecutor() Method

The Executors class in Java provides the newVirtualThreadPerTaskExecutor() method to create an executor that creates a new virtual thread for each task. 

This guide will cover the usage of the newVirtualThreadPerTaskExecutor() method, explain how it works, and provide concise examples to demonstrate its functionality in real-world use cases.

Introduction

The Executors.newVirtualThreadPerTaskExecutor() method creates an executor that uses virtual threads to handle tasks. Virtual threads, introduced in Project Loom, are lightweight threads that make it possible to create many threads without the performance overhead associated with traditional platform threads. This is useful for applications that require a large number of concurrent tasks.

newVirtualThreadPerTaskExecutor Method Syntax

The syntax for the newVirtualThreadPerTaskExecutor method is as follows:

public static ExecutorService newVirtualThreadPerTaskExecutor()

• The method does not take any parameters.
• The method returns an ExecutorService that uses virtual threads to handle tasks.

Examples

Example 1: Basic Usage

In this example, we create a virtual thread per task executor and submit multiple tasks to it. Each task will be handled by a new virtual thread.

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class VirtualThreadPerTaskExecutorExample {
    public static void main(String[] args) {
        // Create a virtual thread per task executor
        ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor();

        // Submit tasks to the executor
        for (int i = 0; i < 5; i++) {
            final int taskNumber = i + 1;
            executor.submit(() -> {
                System.out.println("Executing task " + taskNumber + " by " + Thread.currentThread().getName());
                try {
                    Thread.sleep(1000); // Simulate task execution
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("Task " + taskNumber + " completed by " + Thread.currentThread().getName());
            });
        }

        // Shutdown the executor
        executor.shutdown();
    }
}

Output:

Executing task 1 by VirtualThread-1
Executing task 2 by VirtualThread-2
Executing task 3 by VirtualThread-3
Executing task 4 by VirtualThread-4
Executing task 5 by VirtualThread-5
Task 1 completed by VirtualThread-1
Task 2 completed by VirtualThread-2
Task 3 completed by VirtualThread-3
Task 4 completed by VirtualThread-4
Task 5 completed by VirtualThread-5

Example 2: Handling Multiple Short-Lived Tasks

In this example, we use a virtual thread per task executor to handle multiple short-lived tasks concurrently, demonstrating its capability to manage a large number of tasks efficiently.

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class ShortLivedTasksExample {
    public static void main(String[] args) {
        // Create a virtual thread per task executor
        ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor();

        // Submit short-lived tasks to the executor
        for (int i = 0; i < 10; i++) {
            final int taskNumber = i + 1;
            executor.submit(() -> {
                System.out.println("Task " + taskNumber + " started by " + Thread.currentThread().getName());
                try {
                    Thread.sleep(500); // Simulate a short task
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("Task " + taskNumber + " completed by " + Thread.currentThread().getName());
            });
        }

        // Shutdown the executor
        executor.shutdown();
    }
}

Output:

Task 1 started by VirtualThread-1
Task 2 started by VirtualThread-2
Task 3 started by VirtualThread-3
Task 4 started by VirtualThread-4
Task 5 started by VirtualThread-5
Task 6 started by VirtualThread-6
Task 7 started by VirtualThread-7
Task 8 started by VirtualThread-8
Task 9 started by VirtualThread-9
Task 10 started by VirtualThread-10
Task 1 completed by VirtualThread-1
Task 2 completed by VirtualThread-2
Task 3 completed by VirtualThread-3
Task 4 completed by VirtualThread-4
Task 5 completed by VirtualThread-5
Task 6 completed by VirtualThread-6
Task 7 completed by VirtualThread-7
Task 8 completed by VirtualThread-8
Task 9 completed by VirtualThread-9
Task 10 completed by VirtualThread-10

Example 3: Simulating High-Concurrency Scenarios

In this example, we use a virtual thread per task executor to simulate a high-concurrency scenario where many tasks are submitted simultaneously.

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class HighConcurrencyExample {
    public static void main(String[] args) {
        // Create a virtual thread per task executor
        ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor();

        // Submit a large number of tasks to the executor
        for (int i = 0; i < 100; i++) {
            final int taskNumber = i + 1;
            executor.submit(() -> {
                System.out.println("Task " + taskNumber + " started by " + Thread.currentThread().getName());
                try {
                    Thread.sleep(200); // Simulate a task
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("Task " + taskNumber + " completed by " + Thread.currentThread().getName());
            });
        }

        // Shutdown the executor
        executor.shutdown();
    }
}

Output:

Task 1 started by VirtualThread-1
Task 2 started by VirtualThread-2
...
Task 99 started by VirtualThread-99
Task 100 started by VirtualThread-100
Task 1 completed by VirtualThread-1
Task 2 completed by VirtualThread-2
...
Task 99 completed by VirtualThread-99
Task 100 completed by VirtualThread-100

Conclusion

The Executors.newVirtualThreadPerTaskExecutor() method in Java is used for creating an executor that uses virtual threads to handle tasks. Virtual threads are lightweight and can manage a large number of concurrent tasks efficiently. This method is particularly useful for applications that require high concurrency, such as handling multiple short-lived tasks or simulating high-concurrency scenarios.