* fraction of read operations.
     */
    final AtomicInteger readCount = new AtomicInteger();

    /**
     * A queue of elements currently in the map, ordered by write time. Elements are added to the
     * tail of the queue on write.
     */
    @GuardedBy("this")
    final Queue<ReferenceEntry<K, V>> writeQueue;

    /**

     * fraction of read operations.
     */
    final AtomicInteger readCount = new AtomicInteger();

    /**
     * A queue of elements currently in the map, ordered by write time. Elements are added to the
     * tail of the queue on write.
     */
    @GuardedBy("this")
    final Queue<ReferenceEntry<K, V>> writeQueue;

    /**

        }
        log(logHelper, LogType.FINISHED_THREAD, crawlerContext);
    }

    /**
     * Adds sitemaps from robots.txt to the crawling queue.
     * @param urlQueue The URL queue to add sitemaps to.
     */
    protected void addSitemapsFromRobotsTxt(final UrlQueue<?> urlQueue) {
        final String[] sitemaps = crawlerContext.removeSitemaps();
        if (sitemaps != null) {

    }

    /**
     * Adds a URL to the crawling queue.
     * @param url The URL to add.
     */
    public void addUrl(final String url) {
        try {
            urlQueueService.add(crawlerContext.sessionId, url);
            if (logger.isDebugEnabled()) {
                logger.debug("Added URL to queue: url={}, sessionId={}", url, crawlerContext.sessionId);
            }

    WeakValueReferenceImpl(ReferenceQueue<V> queue, V referent, E entry) {
      super(referent, queue);
      this.entry = entry;
    }

    @Override
    public E getEntry() {
      return entry;
    }

    @Override
    public WeakValueReference<K, V, E> copyFor(ReferenceQueue<V> queue, E entry) {
      return new WeakValueReferenceImpl<>(queue, get(), entry);
    }
  }

  /**

            finishedSessionIdList.add(sessionId);
        }
    }

    /**
     * Deletes all data associated with a specific crawler session.
     * Removes URL filters, URL queues, and access result data for the session.
     *
     * @param sessionId the session ID whose data should be deleted
     */
    private void deleteBySessionId(final String sessionId) {
        try {

      "FINE: Q10000 finished run in   0 µs: task one",
    )
  }

  /**
   * The runner doesn't hold references to its queues! Otherwise we'd need a mechanism to clean them
   * up when they're no longer needed and that's annoying. Instead the task runner only tracks which
   * queues have work scheduled.
   */
  @Test fun activeQueuesContainsOnlyQueuesWithScheduledTasks() {
    redQueue.execute("task one", 100.µs) {

   * <p>After execution begins on a thread from the {@code delegate} {@link Executor}, tasks are
   * polled and executed from a task queue until there are no more tasks. The thread will not be
   * released until there are no more tasks to run.
   *
   * <p>If a task is submitted while a thread is executing tasks from the task queue, the thread
   * will not be released until that submitted task is also complete.
   *

    assertTrue(queue.add("one"));
    assertTrue(queue.add("two"));
    assertTrue(queue.add("three"));
    assertThat(queue.element()).isEqualTo("one");
    assertThat(queue.peek()).isEqualTo("one");
    assertEquals(3, queue.size());
    assertEquals(0, queue.remainingCapacity());

    assertTrue(queue.add("four"));
    assertThat(queue.element()).isEqualTo("two");

        this.filterIndex = filterIndex;
    }

    /**
     * Returns the number of queue shards.
     * @return The number of queue shards.
     */
    public int getQueueShards() {
        return queueShards;
    }

    /**
     * Sets the number of queue shards.
     * @param queueShards The number of queue shards.
     */
    public void setQueueShards(final int queueShards) {