Vert.x HttpClient benchmark

HttpClientBenchmark.java

package io.vertx.example;

import io.vertx.core.AbstractVerticle;
import io.vertx.core.Promise;
import io.vertx.core.Vertx;
import io.vertx.core.http.*;

import java.util.concurrent.CountDownLatch;

public class HttpClientBenchmark extends AbstractVerticle {

    private HttpClient httpClient;
    final int nbWarmupRequestsRequests = 10000;
    final int nbBenchmarkRequestsRequests = 100000;
    int nbRequests;
    int counter;
    int successes = 0;
    int failures = 0;
    private Promise<Void> donePromise = Promise.promise();
    private long begin;

    @Override
    public void start(Promise<Void> startPromise) {
        httpClient = vertx.createHttpClient(new HttpClientOptions().setDefaultHost("127.0.0.1").setDefaultPort(3000).setProtocolVersion(HttpVersion.HTTP_2));
        donePromise.future().onComplete(ar -> startPromise.complete());
        Promise<Void> warmupDonePromise = Promise.promise();
        warmupDonePromise.future().onComplete(ar -> {
            begin = System.currentTimeMillis();
            counter = nbBenchmarkRequestsRequests;
            nbRequests = nbBenchmarkRequestsRequests;
            successes = 0;
            failures = 0;
            runBenchmark(donePromise);
        });
        begin = System.currentTimeMillis();
        counter = nbWarmupRequestsRequests;
        nbRequests = nbWarmupRequestsRequests;
        successes = 0;
        failures = 0;
        runBenchmark(warmupDonePromise);
    }

    public void runBenchmark(Promise<Void> donePromise) {
        httpClient.request(HttpMethod.GET, "/").onComplete(ar -> {
            counter--;
            if (ar.succeeded()) {
                HttpClientRequest req = ar.result();
                req.send().onComplete(ar2 -> {
                    if (ar2.succeeded()) {
                        HttpClientResponse res = ar2.result();
                        res.handler(buffer -> {});
                        if (res.statusCode() == 200)
                            successes++;
                        else
                            failures++;

                    } else {
                        failures++;
                    }
                });
            } else {
                failures++;
            }
            if (counter != 0)
                runBenchmark(donePromise);
            else {
                long end = System.currentTimeMillis();
                System.out.println("Requests: " +nbRequests);
                System.out.println("Successes: " +successes);
                System.out.println("Failures: " +failures);
                System.out.println("Elapsed (ms): " +(end - begin));
                System.out.println("Request/sec: " +1000* nbRequests /(end - begin));
                donePromise.complete();
            }
        });
    }

    public static void main(String[] args) {
        try {
            Vertx vertx = Vertx.vertx();
            CountDownLatch countDownLatch = new CountDownLatch(1);
            vertx.deployVerticle(HttpClientBenchmark.class.getName()).onComplete(ar -> {
                countDownLatch.countDown();
                if (ar.failed())
                    ar.cause().printStackTrace();
            });
            countDownLatch.await();
            System.out.println("done");
            vertx.close();
        } catch (Throwable t) {
            t.printStackTrace();
        }
    }
}