threadpooltest.java

A thread pool is a group of a limited number of threads that are used to execute tasks.

public class ThreadPoolTest {

    public static void main(String[] args) {
        if (args.length != 2) {
            System.out.println("Tests the ThreadPool task.");
            System.out.println(
                "Usage: java ThreadPoolTest numTasks numThreads");
            System.out.println(
                "  numTasks - integer: number of task to run.");
            System.out.println(
                "  numThreads - integer: number of threads " +
                "in the thread pool.");
            return;
        }
        int numTasks = Integer.parseInt(args[0]);
        int numThreads = Integer.parseInt(args[1]);

        // create the thread pool
        ThreadPool threadPool = new ThreadPool(numThreads);

        // run example tasks
        for (int i=0; i<numTasks; i++) {
            threadPool.runTask(createTask(i));
        }

        // close the pool and wait for all tasks to finish.
        threadPool.join();
    }


    /**
        Creates a simple Runnable that prints an ID, waits 500
        milliseconds, then prints the ID again.
    */
    private static Runnable createTask(final int taskID) {
        return new Runnable() {
            public void run() {
                System.out.println("Task " + taskID + ": start");

                // simulate a long-running task
                try {
                    Thread.sleep(500);
                }
                catch (InterruptedException ex) { }

                System.out.println("Task " + taskID + ": end");
            }
        };
    }

}