code: public void run() throws IOException, InterruptedException {
      List<Client> clients = new ArrayList<>(totalClients);
      for (int i = 0; i < totalClients; i++) {
        Client c = new Client(i, totalClients, iterations);
        c.init(txClient, conn.getTable(TABLE));
        c.start();
        clients.add(c);
      }
  
      for (Client c : clients) {
        c.join();
        Closeables.closeQuietly(c);
      }
    }
docs: Runs all clients and waits for them to complete.