A thread pool with the executor framework to execute tasks. Also demonstrates a simple timeout mechanism.

ThreadPool.java

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

/**
 * A thread pool with the executor framework to execute tasks. Also demonstrates a simple timeout mechanism.
 */
public class ThreadPool {

    private static final int NTHREADS = Runtime.getRuntime().availableProcessors();
    private static final int TIMEOUT = 10;

    public static void main(String[] args) {

        System.out.printf("Number of threads: %d%n", NTHREADS);

        ExecutorService pool = Executors.newFixedThreadPool(NTHREADS);
        for (int i = 0; i < 500000; i++) {
            pool.execute(new Worker(i));
        }

        pool.shutdown();

        try {
            if (!pool.awaitTermination(TIMEOUT, TimeUnit.SECONDS)) {
                System.out.printf("Timed out, shutting down now!%n");
                pool.shutdownNow();
            }
        } catch (InterruptedException ie) {
            System.err.printf("Interrupted while waiting for termination%n");
            System.exit(1);
        }

        System.out.printf("Done!");
    }
}

class Worker implements Runnable {

    private long num;

    public Worker(long num) {
        this.num = num;
    }

    @Override
    public void run() {
        System.out.printf("%s will sum: %d%n", Thread.currentThread().getName(), this.num);
        long sum = 0;
        for (long i = 1; i <= num; i++) {
            sum += i;
        }
        System.out.printf("%s got sum: %d%n", Thread.currentThread().getName(), sum);
    }
}