Simulating a Car Manufacturing Line with Phaser and ExecutorService

Welcome back! In this unit, we’re diving into a car manufacturing line simulation using two important concurrency utilities: Phaser and ExecutorService. This lesson will expand your understanding of multi-stage processing and synchronization in Java by simulating real-world scenarios where tasks must follow specific phases.

In this lesson, you’ll learn:

• How to use Phaser to synchronize threads across different stages of a process.
• How to manage threads effectively using ExecutorService.
• How to simulate a car manufacturing line with multiple stages that must coordinate across phases.

By the end of this lesson, you will know how to simulate phased processes using Phaser and manage threads with ExecutorService.

In this lesson, we’re simulating a car manufacturing line with three stages: assembly, painting, and inspection. Multiple cars will be processed simultaneously, but each car must complete a phase before any of them move on to the next. This requires synchronization, which is where Phaser comes in.

Phaser allows us to coordinate threads as they move through each phase, ensuring that no thread moves ahead until all threads are ready to proceed. Meanwhile, ExecutorService helps us manage the thread lifecycle by controlling the submission of tasks and ensuring that the tasks are executed in parallel.

Let’s start by creating the class that simulates the car manufacturing process. The class uses Phaser to synchronize each phase (assembly, painting, inspection) for multiple cars.

import java.util.concurrent.Phaser;

public class CarManufacturingLine {
    private final Phaser phaser;

    public CarManufacturingLine(Phaser phaser) {
        this.phaser = phaser;
    }

In this class, we pass in a Phaser instance that will control the synchronization across all cars. Each car will proceed through three phases: assembly, painting, and inspection.