Is there a java.util.concurrent class that will allow periodic starting of threads without blocking for completion?

Question

I have the following requirement.

I am trying to build a simulator that will generate load on a system for the purpose of load testing. I want threads to start every X milliseconds, each of which will kick off a task that takes Y milliseconds, with Y being maybe 2 or 3 orders of magnitude > X.

I had thought I could use ScheduledExecutorService.scheduleAtFixedRate(). It hasn't worked. I see the following javadoc comment which explains why:

If any execution of this task takes longer than its period, then subsequent executions may start late, but will not concurrently execute.

Concurrent execution is precisely what I want. I want to start a lot of tasks in separate threads, let them do whatever they do, with a big thread pool, and finish when they finish. The point is to generate load for testing load.

Is there anything available in java.util.concurrent that would let me do so? I am reading these javadocs but they are making my head spin now.

Answer 1

You can use the scheduleAtFixedRate(control, 10l, 1l, TimeUnit.SEDONDS) scheduler to create and execute new tasks (in other threads), similar to:

    final ScheduledExecutorService pool = new ScheduledThreadPoolExecutor(100);
    Runnable control = new Runnable()
    {
      public void run() {
        Runnable task = new Runnable() {
          public void run() {
             // do work here
          }
        };
        pool.execute(task);
      };
    };
    pool.scheduleAtFixedRate(control, 5l, 1l, TimeUnit.SECONDS);