Java Project Loom

Project Loom is a proposed open-source project for the Java programming language that aims to improve the performance and scalability of Java applications by introducing lightweight threads, known as "fibers."

Fibers are similar to threads, but they are managed by the Java Virtual Machine (JVM) rather than the operating system, which allows for more efficient use of system resources and better support for concurrent programming. The goal of Project Loom is to make it easier for developers to write concurrent and high-performance applications in Java, without having to deal with the complexity of traditional threading models.

The Fiber Class

In the context of Project Loom, fiber is a type of lightweight thread that is managed by the Java Virtual Machine (JVM) rather than an operating system. Fibers are similar to threads in that they allow a program to execute multiple tasks concurrently, but they are more efficient and easier to use because they are managed by the JVM.

Fibers are created and managed using the new Fiber class in Project Loom, which provides methods for creating, scheduling, and synchronizing fibers. Each fiber is associated with a Runnable or Callable object, which defines the task that the fiber will execute. The Fiber class also provides methods for suspending and resuming fibers, as well as for canceling or completing them.

Here is an example of how you might use fibers in a Java program with Project Loom:

import java.util.concurrent.ForkJoinPool;

import java.util.concurrent.Fiber;

import java.util.concurrent.FiberExecutor;

import java.util.concurrent.TimeUnit;

public class FibersExample {

    public static void main(String[] args) {

        // Create a FiberExecutor using the global ForkJoinPool

        FiberExecutor executor = FiberExecutor.getForkJoinPoolExecutor();

        // Create a new fiber that runs a simple task

        Fiber<Void> fiber = new Fiber<>(executor, () -> {

            // Print a message

            System.out.println("Hello from a fiber!");

        });

        // Start the fiber

        fiber.start();

        // Wait for the fiber to complete

        try {

            fiber.join();

        } catch (InterruptedException e) {

            // Handle interruption

        }

        // Shutdown the executor

        executor.shutdown();

        try {

            executor.awaitTermination(1, TimeUnit.MINUTES);

        } catch (InterruptedException e) {

            // Handle interruption

        }

    }

}

This program creates a new fiber using the Fiber class, and then starts and joins the fiber to run the task it is associated with.

The fiber simply prints a message to the console, but in a real program, the task would likely be more complex and involve the concurrent execution of multiple fibers.

Structured Concurrency

The new Fiber class in Project Loom provides support for structured concurrency. Structured concurrency is a programming paradigm that focuses on the structure and organization of concurrent code, intending to make it easier to write and reason about concurrent programs. It emphasizes the use of explicit control structures and coordination mechanisms to manage concurrent execution, as opposed to the traditional approach of using low-level thread synchronization primitives.

The Fiber class allows developers to create and manage fibers, which are lightweight threads that are managed by the Java Virtual Machine (JVM) rather than the operating system. The Fiber class provides methods for creating, scheduling, and synchronizing fibers, as well as for suspending, resuming, canceling, and completing them.

Here is an example of how you might use structured concurrency in a Java program with Project Loom:

Read here