/**
     * Data transfer object representing process CPU statistics.
     */
    public static class ProcessCpuObj {
        /**
         * Default constructor.
         */
        public ProcessCpuObj() {
            // Default constructor
        }

        /** CPU usage percentage for the process. */
        public short percent;
        /** Total CPU time used by the process in milliseconds. */

        }
    }

    /**
     * Calibrates the CPU load.
     *
     * @return true if the CPU load is within the acceptable range, false otherwise.
     */
    public boolean calibrateCpuLoad() {
        return calibrateCpuLoad(0L);
    }

    /**
     * Calibrates the CPU load with a timeout.
     *
     * @param timeoutInMillis The timeout in milliseconds.

        append(buf, "open", () -> processProbe.getOpenFileDescriptorCount()).append(',');
        append(buf, "max", () -> processProbe.getMaxFileDescriptorCount());
        buf.append("},");
        buf.append("\"cpu\":{");
        append(buf, "percent", () -> processProbe.getProcessCpuPercent()).append(',');
        append(buf, "total", () -> processProbe.getProcessCpuTotalTime());
        buf.append("},");

      }
    };

    public abstract Queue<Integer> create(Comparator<Integer> comparator);
  }

  /**
   * Does a CPU intensive operation on Integer and returns a BigInteger Used to implement an
   * ordering that spends a lot of cpu.
   */
  static class ExpensiveComputation implements Function<Integer, BigInteger> {
    @Override
    public BigInteger apply(Integer from) {

 * java.util.LinkedHashSet}. Generally speaking, this class reduces object allocation and memory
 * consumption at the price of moderately increased constant factors of CPU. Only use this class
 * when there is a specific reason to prioritize memory over CPU.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible // not worth using in GWT for now
final class CompactLinkedHashSet<E extends @Nullable Object> extends CompactHashSet<E> {

                    return "3";
                case "crawler.hotthread.timeout":
                    return "30s";
                case "crawler.hotthread.type":
                    return "cpu";

                default:
                    throw new ConfigPropertyNotFoundException(propertyKey);
                }
            }

            @Override

 * Generally speaking, this class reduces object allocation and memory consumption at the price of
 * moderately increased constant factors of CPU. Only use this class when there is a specific reason
 * to prioritize memory over CPU.
 *
 * @author Dimitris Andreou
 * @author Jon Noack
 */
@GwtIncompatible // not worth using in GWT for now

        this.delayMillisForWaitingNewUrl = delayMillisForWaitingNewUrl;
    }

    /**
     * Delays the crawler while waiting for new URLs to be available.
     * This method calibrates CPU load, checks crawler status, applies
     * interval control rules, and then calls the parent implementation.
     */
    @Override
    protected void delayForWaitingNewUrl() {

      return false;
    }

    if (!finalizeReference(firstReference, finalizeReferentMethod)) {
      return false;
    }

    /*
     * Loop as long as we have references available so as not to waste CPU looking up the Method
     * over and over again.
     */
    while (true) {
      Reference<?> furtherReference = queue.poll();
      if (furtherReference == null) {
        return true;
      }

        blocker = (Blocker) state;
      }
      spinCount++;
      if (spinCount > MAX_BUSY_WAIT_SPINS) {
        /*
         * If we have spun a lot, just park ourselves. This will save CPU while we wait for a slow
         * interrupting thread. In theory, interruptTask() should be very fast, but due to
         * InterruptibleChannel and JavaLangAccess.blockedOn(Thread, Interruptible), it isn't