NanosTest.java

NanosTest.java

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.CountDownLatch;


public final class NanosTest {

	public static void main(final String ... args) throws Exception {

		final int N = 50;
		final int M = 10000;

		final CountDownLatch latch1 = new CountDownLatch(1);
		final CountDownLatch latch2 = new CountDownLatch(N);

		final ConcurrentMap<String, long[]> timesMap = new ConcurrentHashMap<String, long[]>(N);

		for(int i = 0; i < N; i++){

			final Thread thread = new Thread(new Runnable() {

				@Override
				public void run() {
					try {
						final String name = Thread.currentThread().getName();
						latch1.await();

						final long[] times = new long[M];
						for(int j = 0; j < M; j++){
							times[j] = System.nanoTime();
						}

						timesMap.put(name, times);

						latch2.countDown();
					} catch (InterruptedException e) {
					}
				}
			});
			thread.setName("T" + i);
			thread.start();
		}

		latch1.countDown();
		latch2.await();

		String prevName = null;
		long[] prev = null;
		for(int i = 0; i < N; i++){
			final String name = "T" + i;
			final long[] times = timesMap.get(name);
			if (prev != null){
				long diff = 0;
				for(int j = 0; j < M; j++){
					diff += times[j] - prev[j];
				}
				diff /= M;
				System.out.println(name + " - " + prevName + " : " + (diff / 1000) / 1e3 + " ms");
			}
			prevName = name;
			prev = times;
		}
	}
}