Question

I’ve looked through the books/docs about NBP, but there is nothing directly talks about multithreaded programming in NBP. Is there anything particular that needs attention regarding to multithreading in NBP? So, if I want to create a multithreaded NBP application, I just need to follow regular Java multithreaded programming practices, right?

Answer 1

The main thing to look at would be RequestProcessor and RequestProcessor.Task. RequestProcessor is a thread pool; a RequestProcessor.Task is a job.

Most of what RequestProcessor does is similar to what ExecutorService now does in the JDK. The main thing that is not easy w/ just the JDK is creating a task which can be rescheduled and run repeatedly. That is very useful if you, say, want to perform some work after a timeout when the user stops typing:

private static final RequestProcessor rp = new RequestProcessor(MyClass.class);
private RequestProcessor.Task task = rp.create(new Runnable() {
  public void run() {
    //...do some expensive parsing or similar
  }
});

public void keyPressed (KeyEvent ke) {
  task.schedule(200); // (re)schedule the task 200ms in the future;  if schedule() is called again, it will be postponed
}

If you’re using the Nodes API, it is thread-safe, and you can update your nodes as you wish.

If you are doing something which touches Swing components, remember to always run that code with EventQueue.invokeLater(Runnable) – and never use EventQueue.invokeAndWait() – it is a recipe for deadlocks.

If you have code which may sometimes be called on the event thread and sometimes not, NetBeans has a simple way to ensure your code runs on the event thread: Mutex.EVENT.readAccess (new Mutex.Action() { … })