CPU Intensive Calculation Examples?

Question

I need a few easily implementable single cpu and memory intensive calculations that I can write in java for a test thread scheduler.

They should be slightly time con

Answer 1

I was messing around with Thread priority in Java and used the code below. It seems to keep the CPU busy enough that the thread priority makes a difference.

@Test
public void testCreateMultipleThreadsWithDifferentPriorities() throws Exception {
    class MyRunnable implements Runnable {
        @Override
        public void run() {
            for (int i=0; i<1_000_000; i++) {
                double d = tan(atan(tan(atan(tan(atan(tan(atan(tan(atan(123456789.123456789))))))))));
                cbrt(d);
            }
            LOGGER.debug("I am {}, and I have finished", Thread.currentThread().getName());
        }
    }
    final int NUMBER_OF_THREADS = 32;
    List threadList = new ArrayList(NUMBER_OF_THREADS);
    for (int i=1; i<=NUMBER_OF_THREADS; i++) {
        Thread t = new Thread(new MyRunnable());
        if (i == NUMBER_OF_THREADS) {
            // Last thread gets MAX_PRIORITY
            t.setPriority(Thread.MAX_PRIORITY);
            t.setName("T-" + i + "-MAX_PRIORITY");
        } else {
            // All other threads get MIN_PRIORITY
            t.setPriority(Thread.MIN_PRIORITY);
            t.setName("T-" + i);
        }
        threadList.add(t);
    }

    threadList.forEach(t->t.start());
    for (Thread t : threadList) {
        t.join();
    }
}