Executor Framework

1. What is the Executor Framework?

The Executor Framework is a higher-level way of managing and running threads in Java, using a pool of reusable threads instead of manually creating and managing individual Thread objects yourself.

2. Why is it used?

Manually creating a new thread for every single task can be wasteful and hard to manage at scale. The Executor Framework reuses a fixed set of threads efficiently, handling task scheduling for you.

3. Real-Life Example

Think of a call center with a fixed number of staff (a thread pool) handling an incoming stream of customer calls (tasks), rather than hiring a brand-new employee for every single call and letting them go right after.

4. Syntax

java
ExecutorService executor = Executors.newFixedThreadPool(numberOfThreads);
executor.execute(runnableTask);
executor.shutdown();

5. Example Program

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

public class ExecutorDemo {
    public static void main(String[] args) {
        ExecutorService executor = Executors.newFixedThreadPool(2);

        executor.execute(() -> System.out.println("Task 1 executed"));
        executor.execute(() -> System.out.println("Task 2 executed"));

        executor.shutdown();
    }
}

Output:

Task 1 executed
Task 2 executed

6. Key Points to Remember

• ExecutorService manages a pool of threads, reusing them for multiple tasks instead of creating new ones each time.
• Always call shutdown() once done submitting tasks, to allow the program to exit cleanly.
• The Executor Framework is generally preferred over manually managing individual threads in real-world applications.