Fifth-Assignment-Multithread-Basics

Table of contents

• Introduction 👋
• Objectives 🎯
• Tasks 📋
  • Theoretical Questions 📝
  • Practical Questions 💻
• Evaluation ⚖️
• Submission ⌛
• Resources 📚

Introduction 👋

Welcome to your Fifth Advanced Programming (AP) journey, where you'll delve into the fascinating world of multithreading in Java. This project is divided into two main sections:

1. Theoretical Questions: This section is designed to deepen your understanding of key multithreading concepts in Java. You'll have to analyze three code blocks and answer questions about them.

2. Practical Questions: In this section, you'll get hands-on experience with multithreading in Java. Test cases are provided for each problem, but your code will still be manually checked to ensure you've implemented

Objectives 🎯

By completing this assignment, you will:

• Deepen your understanding of multithreading in Java and apply the concepts effectively.
• Gain familiarity with key multithreading concepts such as the Runnable interface, the Thread class, the interrupt() method, and the run() method.

Note that while this assignment covers many important aspects of multithreading, there are some advanced topics such as race condition and synchronization that won't be covered in this assignment and will be introduced in the following week. However, a solid understanding of the concepts covered in this assignment is crucial for grasping those advanced topics.

Tasks 📋

Theoretical Questions 📝

Note: Please answer these questions in a Markdown file and place it in the root directory of your fork. Include code or screenshots where you see fit.

1. What will be printed after interrupting the thread?

public static class SleepThread extends Thread {
        public void run() {
            try {
                Thread.sleep(10000);
            } catch (InterruptedException e) {
                System.out.println("Thread was interrupted!");
            } finally {
                System.out.println("Thread will be finished here!!!");
            }
        }
    }

    public static void main(String[] args) {
        SleepThread thread = new SleepThread();
        thread.start();
        thread.interrupt();
    }

2. In Java, what would be the outcome if the run() method of a Runnable object is invoked directly, without initiating it inside a Thread object?

public class DirectRunnable implements Runnable {
    public void run() {
        System.out.println("Running in: " + Thread.currentThread().getName());
    }
}

public class Main {
    public static void main(String[] args) {
        DirectRunnable runnable = new DirectRunnable();
        runnable.run();
    }
}

3. Elaborate on the sequence of events that occur when the join() method of a thread (let's call it Thread_0) is invoked within the Main() method of a Java program.

public class JoinThread extends Thread {
    public void run() {
        System.out.println("Running in: " + Thread.currentThread().getName());
    }
}

public class Main {
    public static void main(String[] args) {
        JoinThread thread = new JoinThread();
        thread.start();
        try {
            thread.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Back to: " + Thread.currentThread().getName());
    }
}

Practical Questions 💻

Task Scheduler:

• In this problem, you are given an ArrayList of tasks, each with two fields: taskName and processingTime. The goal is to sort these tasks based on their priority, where tasks with longer processing times have higher priority. After sorting, we’ll create separate threads for each task and execute them. Importantly, we’ll wait for each thread to finish its work to ensure the desired execution order. Finally, we’ll return the order of task execution.

Parallelizing Matrix Multiplication:

• In this problem, you are asked to write a program that can parallelize matrix multiplication using multithreading.

• In the ParallelizeMatMul method, you will be given two matrices, A and B. Matrix A has dimensions p × q, and matrix B has dimensions q × r (where both p and r are even numbers). Your task is to compute the product of matrices A and B to obtain a resulting matrix, C. To achieve faster execution, we’ll utilize multithreading.

• Hint:

  • Divide the final matrix C into four equal quarters, as shown in the figure below. Assign each quarter to a separate thread for calculations.

  

  • Procedure:
    1. Divide the quarters among four threads in the ParallelizeMatMul method.
    2. Specify how each thread should calculate the elements in its assigned quarter within its run() method.
    3. Store the calculated elements from each thread in temporary matrices.
    4. Combine the temporary matrices to construct the final matrix C.

Evaluation ⚖️

Your work on this assignment will be evaluated based on:

• Understanding of Multithreading Concepts: Your ability to accurately answer the theoretical questions, demonstrating a deep understanding of multithreading in Java. Remember that the answers to the theoretical questions should be provided separately in a markdown file.

• Test Cases: Your code should pass all the tests provided in the test directory. Make sure to enable GitHub Actions to run the tests on GitHub.

• Code Quality: Your code should be well-structured, readable, and efficient. Proper use of Java conventions, including variable naming, class structure, and comments, will also be considered.

Submission ⌛

1. Add your mentor as a contributor to the project.
2. Create a develop branch for implementing features.
3. Use Git for regular code commits.
4. Push your code and the answers file to the remote repository.
5. Submit a pull request to merge the develop branch with main.

The deadline for submitting your code is Wednesday, May 8 (19th of Ordibehesht)

Resources 📚

For assistance with this assignment, you may refer to the following resources:

🔗 Multithreading in Java on Java Point

🔗 Multithreading in Java on Tutorials Point

🔗 Multithreading in Java on Geeks for Geeks

Also, you can find a wealth of knowledge from various YouTube courses. They can be a great source of learning. Alongside, joining discussions on forums and reading helpful documents can also be beneficial.