private void genAssignmentPlan(TableName tableName,
    SnapshotOfRegionAssignmentFromMeta assignmentSnapshot,
    Map<String, Map<String, Float>> regionLocalityMap, FavoredNodesPlan plan,
    boolean munkresForSecondaryAndTertiary) throws IOException {
    // Get the all the regions for the current table
    List<RegionInfo> regions = assignmentSnapshot.getTableToRegionMap().get(tableName);
    int numRegions = regions.size();

    // Get the current assignment map
    Map<RegionInfo, ServerName> currentAssignmentMap =
      assignmentSnapshot.getRegionToRegionServerMap();

    // Get the all the region servers
    List<ServerName> servers = new ArrayList<>();
    servers.addAll(FutureUtils.get(getConnection().getAdmin().getRegionServers()));

    LOG.info("Start to generate assignment plan for " + numRegions + " regions from table "
      + tableName + " with " + servers.size() + " region servers");

    int slotsPerServer = (int) Math.ceil((float) numRegions / servers.size());
    int regionSlots = slotsPerServer * servers.size();

    // Compute the primary, secondary and tertiary costs for each region/server
    // pair. These costs are based only on node locality and rack locality, and
    // will be modified later.
    float[][] primaryCost = new float[numRegions][regionSlots];
    float[][] secondaryCost = new float[numRegions][regionSlots];
    float[][] tertiaryCost = new float[numRegions][regionSlots];

    if (this.enforceLocality && regionLocalityMap != null) {
      // Transform the locality mapping into a 2D array, assuming that any
      // unspecified locality value is 0.
      float[][] localityPerServer = new float[numRegions][regionSlots];
      for (int i = 0; i < numRegions; i++) {
        Map<String, Float> serverLocalityMap =
          regionLocalityMap.get(regions.get(i).getEncodedName());
        if (serverLocalityMap == null) {
          continue;
        }
        for (int j = 0; j < servers.size(); j++) {
          String serverName = servers.get(j).getHostname();
          if (serverName == null) {
            continue;
          }
          Float locality = serverLocalityMap.get(serverName);
          if (locality == null) {
            continue;
          }
          for (int k = 0; k < slotsPerServer; k++) {
            // If we can't find the locality of a region to a server, which occurs
            // because locality is only reported for servers which have some
            // blocks of a region local, then the locality for that pair is 0.
            localityPerServer[i][j * slotsPerServer + k] = locality.floatValue();
          }
        }
      }

      // Compute the total rack locality for each region in each rack. The total
      // rack locality is the sum of the localities of a region on all servers in
      // a rack.
      Map<String, Map<RegionInfo, Float>> rackRegionLocality = new HashMap<>();
      for (int i = 0; i < numRegions; i++) {
        RegionInfo region = regions.get(i);
        for (int j = 0; j < regionSlots; j += slotsPerServer) {
          String rack = rackManager.getRack(servers.get(j / slotsPerServer));
          Map<RegionInfo, Float> rackLocality = rackRegionLocality.get(rack);
          if (rackLocality == null) {
            rackLocality = new HashMap<>();
            rackRegionLocality.put(rack, rackLocality);
          }
          Float localityObj = rackLocality.get(region);
          float locality = localityObj == null ? 0 : localityObj.floatValue();
          locality += localityPerServer[i][j];
          rackLocality.put(region, locality);
        }
      }
      for (int i = 0; i < numRegions; i++) {
        for (int j = 0; j < regionSlots; j++) {
          String rack = rackManager.getRack(servers.get(j / slotsPerServer));
          Float totalRackLocalityObj = rackRegionLocality.get(rack).get(regions.get(i));
          float totalRackLocality =
            totalRackLocalityObj == null ? 0 : totalRackLocalityObj.floatValue();

          // Primary cost aims to favor servers with high node locality and low
          // rack locality, so that secondaries and tertiaries can be chosen for
          // nodes with high rack locality. This might give primaries with
          // slightly less locality at first compared to a cost which only
          // considers the node locality, but should be better in the long run.
          primaryCost[i][j] = 1 - (2 * localityPerServer[i][j] - totalRackLocality);

          // Secondary cost aims to favor servers with high node locality and high
          // rack locality since the tertiary will be chosen from the same rack as
          // the secondary. This could be negative, but that is okay.
          secondaryCost[i][j] = 2 - (localityPerServer[i][j] + totalRackLocality);

          // Tertiary cost is only concerned with the node locality. It will later
          // be restricted to only hosts on the same rack as the secondary.
          tertiaryCost[i][j] = 1 - localityPerServer[i][j];
        }
      }
    }

    if (this.enforceMinAssignmentMove && currentAssignmentMap != null) {
      // We want to minimize the number of regions which move as the result of a
      // new assignment. Therefore, slightly penalize any placement which is for
      // a host that is not currently serving the region.
      for (int i = 0; i < numRegions; i++) {
        for (int j = 0; j < servers.size(); j++) {
          ServerName currentAddress = currentAssignmentMap.get(regions.get(i));
          if (currentAddress != null && !currentAddress.equals(servers.get(j))) {
            for (int k = 0; k < slotsPerServer; k++) {
              primaryCost[i][j * slotsPerServer + k] += NOT_CURRENT_HOST_PENALTY;
            }
          }
        }
      }
    }

    // Artificially increase cost of last slot of each server to evenly
    // distribute the slop, otherwise there will be a few servers with too few
    // regions and many servers with the max number of regions.
    for (int i = 0; i < numRegions; i++) {
      for (int j = 0; j < regionSlots; j += slotsPerServer) {
        primaryCost[i][j] += LAST_SLOT_COST_PENALTY;
        secondaryCost[i][j] += LAST_SLOT_COST_PENALTY;
        tertiaryCost[i][j] += LAST_SLOT_COST_PENALTY;
      }
    }

    RandomizedMatrix randomizedMatrix = new RandomizedMatrix(numRegions, regionSlots);
    primaryCost = randomizedMatrix.transform(primaryCost);
    int[] primaryAssignment = new MunkresAssignment(primaryCost).solve();
    primaryAssignment = randomizedMatrix.invertIndices(primaryAssignment);

    // Modify the secondary and tertiary costs for each region/server pair to
    // prevent a region from being assigned to the same rack for both primary
    // and either one of secondary or tertiary.
    for (int i = 0; i < numRegions; i++) {
      int slot = primaryAssignment[i];
      String rack = rackManager.getRack(servers.get(slot / slotsPerServer));
      for (int k = 0; k < servers.size(); k++) {
        if (!rackManager.getRack(servers.get(k)).equals(rack)) {
          continue;
        }
        if (k == slot / slotsPerServer) {
          // Same node, do not place secondary or tertiary here ever.
          for (int m = 0; m < slotsPerServer; m++) {
            secondaryCost[i][k * slotsPerServer + m] = MAX_COST;
            tertiaryCost[i][k * slotsPerServer + m] = MAX_COST;
          }
        } else {
          // Same rack, do not place secondary or tertiary here if possible.
          for (int m = 0; m < slotsPerServer; m++) {
            secondaryCost[i][k * slotsPerServer + m] = AVOID_COST;
            tertiaryCost[i][k * slotsPerServer + m] = AVOID_COST;
          }
        }
      }
    }
    if (munkresForSecondaryAndTertiary) {
      randomizedMatrix = new RandomizedMatrix(numRegions, regionSlots);
      secondaryCost = randomizedMatrix.transform(secondaryCost);
      int[] secondaryAssignment = new MunkresAssignment(secondaryCost).solve();
      secondaryAssignment = randomizedMatrix.invertIndices(secondaryAssignment);

      // Modify the tertiary costs for each region/server pair to ensure that a
      // region is assigned to a tertiary server on the same rack as its secondary
      // server, but not the same server in that rack.
      for (int i = 0; i < numRegions; i++) {
        int slot = secondaryAssignment[i];
        String rack = rackManager.getRack(servers.get(slot / slotsPerServer));
        for (int k = 0; k < servers.size(); k++) {
          if (k == slot / slotsPerServer) {
            // Same node, do not place tertiary here ever.
            for (int m = 0; m < slotsPerServer; m++) {
              tertiaryCost[i][k * slotsPerServer + m] = MAX_COST;
            }
          } else {
            if (rackManager.getRack(servers.get(k)).equals(rack)) {
              continue;
            }
            // Different rack, do not place tertiary here if possible.
            for (int m = 0; m < slotsPerServer; m++) {
              tertiaryCost[i][k * slotsPerServer + m] = AVOID_COST;
            }
          }
        }
      }

      randomizedMatrix = new RandomizedMatrix(numRegions, regionSlots);
      tertiaryCost = randomizedMatrix.transform(tertiaryCost);
      int[] tertiaryAssignment = new MunkresAssignment(tertiaryCost).solve();
      tertiaryAssignment = randomizedMatrix.invertIndices(tertiaryAssignment);

      for (int i = 0; i < numRegions; i++) {
        List<ServerName> favoredServers =
          new ArrayList<>(FavoredNodeAssignmentHelper.FAVORED_NODES_NUM);
        ServerName s = servers.get(primaryAssignment[i] / slotsPerServer);
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));

        s = servers.get(secondaryAssignment[i] / slotsPerServer);
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));

        s = servers.get(tertiaryAssignment[i] / slotsPerServer);
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));
        // Update the assignment plan
        plan.updateFavoredNodesMap(regions.get(i), favoredServers);
      }
      LOG.info("Generated the assignment plan for " + numRegions + " regions from table "
        + tableName + " with " + servers.size() + " region servers");
      LOG.info("Assignment plan for secondary and tertiary generated " + "using MunkresAssignment");
    } else {
      Map<RegionInfo, ServerName> primaryRSMap = new HashMap<>();
      for (int i = 0; i < numRegions; i++) {
        primaryRSMap.put(regions.get(i), servers.get(primaryAssignment[i] / slotsPerServer));
      }
      FavoredNodeAssignmentHelper favoredNodeHelper =
        new FavoredNodeAssignmentHelper(servers, conf);
      favoredNodeHelper.initialize();
      Map<RegionInfo, ServerName[]> secondaryAndTertiaryMap =
        favoredNodeHelper.placeSecondaryAndTertiaryWithRestrictions(primaryRSMap);
      for (int i = 0; i < numRegions; i++) {
        List<ServerName> favoredServers =
          new ArrayList<>(FavoredNodeAssignmentHelper.FAVORED_NODES_NUM);
        RegionInfo currentRegion = regions.get(i);
        ServerName s = primaryRSMap.get(currentRegion);
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));

        ServerName[] secondaryAndTertiary = secondaryAndTertiaryMap.get(currentRegion);
        s = secondaryAndTertiary[0];
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));

        s = secondaryAndTertiary[1];
        favoredServers
          .add(ServerName.valueOf(s.getHostname(), s.getPort(), ServerName.NON_STARTCODE));
        // Update the assignment plan
        plan.updateFavoredNodesMap(regions.get(i), favoredServers);
      }
      LOG.info("Generated the assignment plan for " + numRegions + " regions from table "
        + tableName + " with " + servers.size() + " region servers");
      LOG.info("Assignment plan for secondary and tertiary generated "
        + "using placeSecondaryAndTertiaryWithRestrictions method");
    }
  }
Generate the assignment plan for the existing table
@param munkresForSecondaryAndTertiary if set on true the assignment plan for the tertiary and
                                      secondary will be generated with Munkres algorithm,
                                      otherwise will be generated using
                                      placeSecondaryAndTertiaryRS
hbase-server/src/main/java/org/apache/hadoop/hbase/master/RegionPlacementMaintainer.java