* <p>Note: If a parameter is set to {@code null}, the corresponding ThreadLocal variable is removed.</p>
 */
public final class CrawlingParameterUtil {
    private static final ThreadLocal<UrlQueue<?>> URL_QUEUE_THREAD_LOCAL = new ThreadLocal<>();

    private static final ThreadLocal<CrawlerContext> ROBOT_CONTEXT_THREAD_LOCAL = new ThreadLocal<>();

    /** Constant for Kryo serializer type. */
    protected static final String KRYO = "kryo";

    /** ThreadLocal container for Kryo instances to ensure thread safety. */
    protected final ThreadLocal<Kryo> kryoThreadLocal;

    /**
     * Constructs a new DataSerializer.
     * <p>
     * Initializes the ThreadLocal Kryo instances with appropriate configuration.

    /** Per-thread queue of events to dispatch. */
    @SuppressWarnings("ThreadLocalUsage") // Each Dispatcher needs its own state.
    private final ThreadLocal<Queue<Event>> queue =
        new ThreadLocal<Queue<Event>>() {
          @Override
          protected Queue<Event> initialValue() {
            return new ArrayDeque<>();
          }
        };

     */
    protected Set<String> robotsTxtUrlSet = new LruHashSet<>(10000);

    /**
     * Thread-local storage for sitemaps.
     */
    protected ThreadLocal<String[]> sitemapsLocal = new ThreadLocal<>();

    /** The number of threads used by the crawler */
    protected int numOfThread = 10;

    /** The maximum number of times to check for active threads. */

package com.google.common.escape;

/**
 * @author Jesse Wilson
 */
final class Platform {

  private static final char[] CHAR_BUFFER = new char[1024];

  static char[] charBufferFromThreadLocal() {
    // ThreadLocal is not available to GWT, so we always reuse the same
    // instance.  It is always safe to return the same instance because
    // javascript is single-threaded, and only used by blocks that doesn't
    // involve async callbacks.

    protected Map<String, String> metadataXpathMap = new HashMap<>();

    /** Thread-local instance of XPathAPI for thread-safe XPath evaluation. */
    private final ThreadLocal<XPathAPI> xpathAPI = new ThreadLocal<>();

    /**
     * Creates a new HtmlExtractor instance.
     */
    public HtmlExtractor() {
        super();
    }

    @Override

/**
 * Most websites serve cookies in the blessed format. Eagerly create the parser to ensure such
 * cookies are on the fast path.
 */
private val STANDARD_DATE_FORMAT =
  object : ThreadLocal<DateFormat>() {
    override fun initialValue(): DateFormat {
      // Date format specified by RFC 7231 section 7.1.1.1.
      return SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss 'GMT'", Locale.US).apply {