Thread Pool Design Pattern

Overview

The Thread Pool Design Pattern is a concurrency pattern that maintains a pool of threads to perform tasks, reusing existing threads instead of creating new ones. This helps manage system resources efficiently and improves application performance.

Key Characteristics

• Limits the number of threads created to improve resource utilization.
• Reuses threads for multiple tasks, reducing the overhead of thread creation and destruction.
• Provides a mechanism for queuing tasks when all threads are busy.

Implementation

The following is an example of a Thread Pool implementation in Java:

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

class Task implements Runnable {
    private final String name;

    public Task(String name) {
        this.name = name;
    }

    @Override
    public void run() {
        System.out.println("Task " + name + " is being executed by " + Thread.currentThread().getName());
        try {
            Thread.sleep(2000); // Simulate task execution time
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Task " + name + " is finished.");
    }
}

public class ThreadPoolDemo {
    public static void main(String[] args) {
        // Create a thread pool with 3 threads
        ExecutorService executorService = Executors.newFixedThreadPool(3);

        // Submit tasks to the thread pool
        for (int i = 1; i <= 5; i++) {
            Task task = new Task("Task-" + i);
            executorService.submit(task);
        }

        // Shutdown the thread pool
        executorService.shutdown();
    }
}
    

When to Use

• When you have multiple tasks to execute concurrently.
• When creating and destroying threads frequently would lead to performance overhead.
• When you want to limit the number of concurrent threads to avoid resource contention.

Advantages

• Reduces the overhead of thread creation and destruction.
• Efficient use of system resources by limiting the number of active threads.
• Improves application performance by reusing threads for multiple tasks.

Disadvantages

• Requires careful configuration of the thread pool size to balance performance and resource usage.
• May lead to task queuing or delays if all threads are busy and the pool size is insufficient.

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