Run static method from thread pool in java

Question

What is the best way to run a static method on multiple threads using a thread pool? I am also trying to pass an argument to a static method. sort of

Class A{
 public static runTask(int i){
   ....
 }

}

and from the main:

ThreadPool pool = new ThreadPool(5, "poolname");

for(int i=1; i<10; i++){

   A.runTask(i) // but on a new thread...

}

Thank!

Answer 1

See the documentation for java.util.concurrent.Executors . It should fit your needs. Here is a simple example of its use:

public class ExecutorServiceTest {
    static ExecutorService threadPool = Executors.newCachedThreadPool();

    public static void main(String[] args) throws Exception {
        // Queue 10 executions of someTask into the threadPool 
        for(int i = 0; i < 10; i++) {
            runSomeTaskInThreadPool();
        }
        // the shutdown method causes the executor to:
        // 1. stop accepting new tasks, and
        // 2. allow previously queued jobs to complete, and
        // 3. shut down all pooled threads once all jobs are complete  
        threadPool.shutdown();
        // block until the threadPool has finished shutting down,
        // which indicates that all tasks have finished executing
        threadPool.awaitTermination(Long.MAX_VALUE, TimeUnit.MILLISECONDS);
    }

    private static void runSomeTaskInThreadPool() {
        Future future = threadPool.submit(new Runnable() {
            public void run() {
                someTask();
            }
        });
        // TODO: Maybe keep track of futures to monitor success/failure of task
    }

    static AtomicInteger counter = new AtomicInteger();
    public static void someTask() {
        System.out.println("someTask: " + counter.incrementAndGet() 
                + " on thread: " + Thread.currentThread());
    }
}

Answer 2

Check out our detailed implementation guides: http://java.sun.com/developer/Books/javaprogramming/threads/chap13.pdf