Hanging test

MyTest.java

package io.vertx.monitoring;

import io.vertx.core.Vertx;
import io.vertx.ext.unit.Async;
import io.vertx.ext.unit.TestContext;
import io.vertx.ext.unit.junit.VertxUnitRunner;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;

import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.atomic.LongAdder;

/**
 * @author Joel Takvorian
 */
@RunWith(VertxUnitRunner.class)
public class MyTest {
  private static final int SENT_COUNT = 5;

  private final int concurrentClients = ForkJoinPool.commonPool().getParallelism();
  private Vertx vertx;

  @Before
  public void setUp(TestContext ctx) {
    vertx = Vertx.vertx();
    System.out.println("setUp complete");
  }

  @After
  public void teardown() {
    System.out.println("tearDown complete");
  }

  @Test
  public void test(TestContext ctx) throws InterruptedException {
    System.out.println("starting test [expecting " + concurrentClients*SENT_COUNT + " async tasks]");
    Async clientsFinished = ctx.async(concurrentClients);
    LongAdder la = new LongAdder();
    for (int i = 0; i < concurrentClients; i++) {
      ForkJoinPool.commonPool().execute(() -> {
        for (int j = 0; j < SENT_COUNT; j++) {
          Async async = ctx.async();
          vertx.setTimer(30, h -> {
            async.complete();
            la.increment();
            System.out.println("completed n." + la.intValue());
          });
          async.await();
        }
        clientsFinished.countDown();
      });
    }
    System.out.println("awaiting...");
    clientsFinished.awaitSuccess();
    System.out.println("test finished");
  }
}