public Object measureSize() {
    for (Thread thread : blockedThreads) {
      thread.interrupt();
    }
    blockedThreads.clear();
    Facade<Object> f = impl.newFacade();
    for (int i = 0; i < numThreads; i++) {
      Thread thread =
          new Thread() {
            @Override
            public void run() {
              try {
                f.get();