webSocket.close(1000, null);
    System.out.println("CLOSE: " + code + " " + reason);
  }

  @Override public void onFailure(WebSocket webSocket, Throwable t, Response response) {
    t.printStackTrace();
  }

  public static void main(String... args) {
    new WebSocketEcho().run();
  }

    for (int i = 0; i < threadCount; i++) {
      executor.execute(() -> {
        try {
          drainQueue();
        } catch (Exception e) {
          e.printStackTrace();
        }
      });
    }
    executor.shutdown();
  }

  private void drainQueue() throws Exception {
    for (HttpUrl url; (url = queue.take()) != null; ) {
      if (!fetchedUrls.add(url)) {

            Thread.sleep(10);
            sink.writeUtf8(String.format(" * %s = %s\n", i, factor(i)));
          }
          sink.close();
        } catch (IOException | InterruptedException e) {
          e.printStackTrace();
        }
      }

      private String factor(int n) {
        for (int i = 2; i < n; i++) {
          int x = n / i;
          if (x * i == n) return factor(x) + " × " + i;
        }

        .url("http://publicobject.com/helloworld.txt")
        .build();

    client.newCall(request).enqueue(new Callback() {
      @Override public void onFailure(Call call, IOException e) {
        e.printStackTrace();
      }

      @Override public void onResponse(Call call, Response response) throws IOException {
        try (ResponseBody responseBody = response.body()) {