I am trying to write a program in Java using ExecutorService and it's function invokeAll. My question is: does the invokeAll functions solve the tasks simultaneously? I mean, if i have two processors, there will be two workers in the same time? Because a can't make it to scale correct. It takes the same time to complete the problem if i give newFixedThreadPool(2) or 1.

List<Future<PartialSolution>> list = new ArrayList<Future<PartialSolution>>();
Collection<Callable<PartialSolution>> tasks = new ArrayList<Callable<PartialSolution>>();
for(PartialSolution ps : wp)
{
    tasks.add(new Map(ps, keyWords));
}
list = executor.invokeAll(tasks);

Map is a class that implements Callable and wp is a vector of Partial Solutions, a class that holds some informations in different times.

Why doesn't it scale? What could be the problem?

Thank you, Alex