call: Call,
    delay: Long,
  ): Thread {
    val thread =
      object : Thread("canceler") {
        override fun run() {
          try {
            sleep(delay)
          } catch (e: InterruptedException) {
            throw AssertionError()
          }
          call.cancel()
        }
      }
    thread.start()
    return thread
  }

/**
 * A {@link TransferListener} implementation that wraps another delegate {@link TransferListener} but makes it run
 * on single thread, keeping the listener logic simple. This listener also blocks on last transfer event to allow
 * output to perform possible cleanup. It spawns a daemon thread to consume queued events that may fall in even
 * concurrently.
 *
 * @since 4.0.0
 */

        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;

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.

        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
  }

  /** Invokes {@code toJoin.}{@link Thread#join() join()} uninterruptibly. */
  @J2ktIncompatible
  @GwtIncompatible // concurrency
  public static void joinUninterruptibly(Thread toJoin) {
    boolean interrupted = false;
    try {
      while (true) {
        try {

Calls are executed in one of two ways:

 * **Synchronous:** your thread blocks until the response is readable.
 * **Asynchronous:** you enqueue the request on any thread, and get [called back](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-callback/) on another thread when the response is readable.

            SingletonLaContainerFactory.init();

            final Thread shutdownCallback = new Thread("ShutdownHook") {
                @Override
                public void run() {
                    destroyContainer();
                }

            };
            Runtime.getRuntime().addShutdownHook(shutdownCallback);

            commandThread = new Thread(() -> {

  }

  @SuppressWarnings("ThreadPriorityCheck") // TODO: b/175898629 - Consider onSpinWait.
  static void awaitWaiting(Thread t) {
    while (true) {
      Thread.State state = t.getState();
      switch (state) {
        case RUNNABLE:
        case BLOCKED:
          Thread.yield();
          break;
        case WAITING:
          return;
        default:

        }

        ClassLoader oldClassLoader = Thread.currentThread().getContextClassLoader();
        try {
            Thread.currentThread().setContextClassLoader(pluginDescriptor.getClassRealm());

            return container.lookup(role, roleHint);
        } finally {
            Thread.currentThread().setContextClassLoader(oldClassLoader);
        }
    }

  }

  /** Receive frames until there are no more. Invoked only by the reader thread. */
  @Throws(IOException::class)
  fun loopReader(response: Response) {
    try {
      listener.onOpen(this@RealWebSocket, response)
      while (receivedCloseCode == -1) {
        // This method call results in one or more onRead* methods being called on this thread.
        reader!!.processNextFrame()
      }
    } catch (e: Exception) {