}

            seen = true;

            tg = aTgList;
            Thread[] ts = new Thread[tg.activeCount()];
            tg.enumerate(ts);

            for (Thread active : ts) {
                String name = active.getName();
                boolean daemon = active.isDaemon();
                assertTrue(daemon, name + " is no daemon Thread.");
            }
        }

        Set<String> valueSet = Collections.synchronizedSet(new HashSet<>());
        Thread[] threads = new Thread[threadNum];
        ESSourceReader reader = new ESSourceReader(client, settings, indexName);
        reader.setScrollSize(100);
        for (int i = 0; i < threadNum; i++) {
            threads[i] = new Thread(() -> {
                Map<String, Object> source;

      return;
    }
    TimedWaiterThread thread = new TimedWaiterThread(new AbstractFuture<Object>() {}, 2, SECONDS);
    thread.start();
    thread.awaitWaiting();
    Thread.class.getMethod("suspend").invoke(thread);
    // Sleep for enough time to add 1500 milliseconds of overwait to the get() call.
    long toWaitMillis = 3500 - NANOSECONDS.toMillis(System.nanoTime() - thread.startTime);
    Thread.sleep(toWaitMillis);

  /** Returns a new started daemon Thread running the given runnable. */
  final Thread newStartedThread(Runnable runnable) {
    Thread t = new Thread(runnable);
    t.setDaemon(true);
    t.start();
    return t;
  }

  /**
   * Waits for the specified time (in milliseconds) for the thread to terminate (using {@link
   * Thread#join(long)}), else interrupts the thread (in the hope that it may terminate later) and

public class DeferredTest {
    @Test
    public void test_doneBeforeResolve() throws Exception {
        final Deferred<SuggestResponse> deferred = new Deferred<>();

        Thread th = new Thread(() -> {
            try {
                Thread.sleep(100);
            } catch (InterruptedException ignore) {}
            deferred.resolve(new SuggestResponse("", 0, Collections.emptyList(), 0, null));
        });
        th.start();

    assertTrue(Thread.holdsLock(mutex));
    return super.add(o);
  }

  @Override
  public boolean addAll(Collection<? extends E> c) {
    assertTrue(Thread.holdsLock(mutex));
    return super.addAll(c);
  }

  @Override
  public void clear() {
    assertTrue(Thread.holdsLock(mutex));
    super.clear();
  }

  @Override
  public boolean contains(@Nullable Object o) {
    assertTrue(Thread.holdsLock(mutex));

    assertTrue(Thread.holdsLock(mutex));
    return super.add(o);
  }

  @Override
  public boolean addAll(Collection<? extends E> c) {
    assertTrue(Thread.holdsLock(mutex));
    return super.addAll(c);
  }

  @Override
  public void clear() {
    assertTrue(Thread.holdsLock(mutex));
    super.clear();
  }

  @Override
  public boolean contains(@Nullable Object o) {
    assertTrue(Thread.holdsLock(mutex));

So we have a dedicated thread for every socket that just reads frames and dispatches them.

The reader thread must never run application-layer code. Otherwise one slow stream can hold up the entire connection.

            monitor.leave();
          }
        });
    awaitUninterruptibly(enteredLatch);
  }

  @CanIgnoreReturnValue
  static Thread startThread(Runnable runnable) {
    Thread thread = new Thread(runnable);
    thread.setDaemon(true);
    thread.start();
    return thread;
  }

  /**
   * Generates a test case verifying that calling any enterXxx, tryEnterXxx, or waitForXxx method

    }

    @Override
    public int size() {
      assertTrue(Thread.holdsLock(mutex));
      return super.size();
    }

    @Override
    public boolean isEmpty() {
      assertTrue(Thread.holdsLock(mutex));
      return super.isEmpty();
    }

    @Override
    public @Nullable V remove(Object object) {
      assertTrue(Thread.holdsLock(mutex));
      return super.remove(object);
    }

    @Override