docs: protected synchronized long seekUnusedZero(Long bucketId, Aggressiveness aggressiveness) {
          AtomicLong freeSpace = new AtomicLong(0);
  
          int totalElements = (int) memoryHandler.getAllocatedHostObjects(bucketId);
  
          // these 2 variables will contain jvm-wise memory access frequencies
          float shortAverage = zeroShort.getAverage();
          float longAverage = zeroLong.getAverage();
  
          // threshold is calculated based on agressiveness specified via configuration
          float shortThreshold = shortAverage / (Aggressiveness.values().length - aggressiveness.ordinal());
          float longThreshold = longAverage / (Aggressiveness.values().length - aggressiveness.ordinal());
  
          // simple counter for dereferenced objects
          AtomicInteger elementsDropped = new AtomicInteger(0);
          AtomicInteger elementsSurvived = new AtomicInteger(0);
  
          for (Long object : memoryHandler.getHostTrackingPoints(bucketId)) {
              AllocationPoint point = getAllocationPoint(object);
  
              // point can be null, if memory was promoted to device and was deleted there
              if (point == null)
                  continue;
  
              if (point.getAllocationStatus() == AllocationStatus.HOST) {
                  //point.getAccessState().isToeAvailable()
                  //point.getAccessState().requestToe();
  
                  /*
                      Check if memory points to non-existant buffer, using externals.
                      If externals don't have specified buffer - delete reference.
                   */
                  if (point.getBuffer() == null) {
                      purgeZeroObject(bucketId, object, point, false);
                      freeSpace.addAndGet(AllocationUtils.getRequiredMemory(point.getShape()));
  
                      elementsDropped.incrementAndGet();
                      continue;
                  } else {
                      elementsSurvived.incrementAndGet();
                  }
  
                  //point.getAccessState().releaseToe();
              } else {
                  //  log.warn("SKIPPING :(");
              }
          }
  
  
  
          //log.debug("Short average: ["+shortAverage+"], Long average: [" + longAverage + "]");
          //log.debug("Aggressiveness: ["+ aggressiveness+"]; Short threshold: ["+shortThreshold+"]; Long threshold: [" + longThreshold + "]");
          log.debug("Zero {} elements checked: [{}], deleted: {}, survived: {}", bucketId, totalElements,
                          elementsDropped.get(), elementsSurvived.get());
  
          return freeSpace.get();
      }