if (++i == DRAIN_MAX) {
          break;
        }
      }
    }

    /** Clears all entries from the key and value reference queues. */
    void clearReferenceQueues() {
      if (map.usesKeyReferences()) {
        clearKeyReferenceQueue();
      }
      if (map.usesValueReferences()) {
        clearValueReferenceQueue();
      }
    }