*
     * @return the {@link UrlQueue} instance associated with the current thread, or {@code null} if none is set.
     */
    public static UrlQueue<?> getUrlQueue() {
        return URL_QUEUE_THREAD_LOCAL.get();
    }

    /**
     * Sets the URL queue for the current thread. If the provided URL queue is null,
     * the URL queue for the current thread is removed.
     *

  class Interruptenator extends Thread {
    final AtomicBoolean shutdown;

    Interruptenator(Thread interruptee) {
      this(interruptee, new AtomicBoolean(false));
    }

    @SuppressWarnings("ThreadPriorityCheck") // TODO: b/175898629 - Consider onSpinWait.
    Interruptenator(Thread interruptee, AtomicBoolean shutdown) {
      super(
          new Runnable() {

    @Override
    public boolean offer(E o) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.offer(o);
    }

    @Override
    public @Nullable E poll() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.poll();
    }

    @Override
    public E remove() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.remove();
    }

    @Override

 * thread) the subscriber is actually called when an event is dispatched to it.
 *
 * @author Colin Decker
 */
abstract class Dispatcher {

  /**
   * Returns a dispatcher that queues events that are posted reentrantly on a thread that is already
   * dispatching an event, guaranteeing that all events posted on a single thread are dispatched to

  }

  /**
   * Causes this thread to call the named method, and asserts that this thread becomes blocked on
   * the lock-like object. The lock-like object must have a method equivalent to {@link
   * java.util.concurrent.locks.ReentrantLock#hasQueuedThread(Thread)}.
   */
  public void callAndAssertBlocks(String methodName, Object... arguments) throws Exception {

        }
      }
    } 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 {

     *       observing a null thread does not mean the object is safe to reuse.
     *   <li>If this field's value is some other thread object, we know that it's not our thread.
     *   <li>If this field's value == null because it originally belonged to another thread and that
     *       thread cleared it, we still know that it's not associated with our thread

            int nextValue = counter + 1;
            Thread.yield();
            counter = nextValue;
            return counter;
          }
        };

    int numThreads = 10;
    int iterations = 1000;
    Thread[] threads = new Thread[numThreads];
    for (int i = 0; i < numThreads; i++) {
      threads[i] =
          new Thread() {
            @Override
            public void run() {

            int nextValue = counter + 1;
            Thread.yield();
            counter = nextValue;
            return counter;
          }
        };

    int numThreads = 10;
    int iterations = 1000;
    Thread[] threads = new Thread[numThreads];
    for (int i = 0; i < numThreads; i++) {
      threads[i] =
          new Thread() {
            @Override
            public void run() {

public class BuildThreadFactory implements ThreadFactory {
    private final AtomicInteger id = new AtomicInteger();

    private static final String PREFIX = "BuilderThread";

    @Override
    public Thread newThread(Runnable r) {
        return new Thread(r, String.format("%s-%d", PREFIX, id.getAndIncrement()));
    }