reco

GraphTraversalSource traversal = titanGraph.traversal();

        long startSimilarQuery = System.currentTimeMillis();
        List<Vertex> similars = traversal.V()
                .has(USER_LABEL, USER_ID_PROPERTY, userId)
                .outE(SIMILAR_RELATIONSHIP)
                .order()
                .by(new Comparator<Edge>() {
                    @Override
                    public int compare(Edge o1, Edge o2) {
                        Integer similarO1 = (Integer) o1.property(SIMILAR_WEIGHT_RELATIONSHIP_PROPERTY).value();
                        Integer similarO2 = (Integer) o2.property(SIMILAR_WEIGHT_RELATIONSHIP_PROPERTY).value();
                        return (-1) * similarO1.compareTo(similarO2);
                    }
                })
                .inV()
                .toList();
        long endSimilarQuery = System.currentTimeMillis();
        log.info("Stats : Fetch similars query tooks : {} with result size : {}",
                endSimilarQuery - startSimilarQuery, similars.size());

        if (similars.isEmpty()) {
            log.info("There is no similar users for user with id : {}", userId);
            return emptyList();
        }

        long startKnowPersonsQuery = System.currentTimeMillis();
        Set knownPersonIds = traversal.V()
                .has(USER_LABEL, USER_ID_PROPERTY, userId)
                .out()
                .properties(USER_ID_PROPERTY)
                .value()
                .toSet();
        long endKnowPersonsQuery = System.currentTimeMillis();
        log.info("Stats : Fetch known person query tooks : {} with result size : {}",
                endKnowPersonsQuery - startKnowPersonsQuery, knownPersonIds.size());

        log.info("User knows {} persons", knownPersonIds.size());

        long startSimilarIteration = System.currentTimeMillis();
        List recoList = new ArrayList();
        for (Vertex each : similars) {

            if (recoList.size() < limit) {
                GraphTraversal<Vertex, Vertex> simTraversal =
                        traversal
                                .V(each.id())
                                .out(LIKE_RELATIONSHIP, MATCH_RELATIONSHIP)
                                .has(USER_LABEL, USER_HIDDEN_PROPERTY, false);

                if (nonNull(gender) && (
                        Objects.equals(gender.toLowerCase(), "male")) ||
                        Objects.equals(gender.toLowerCase(), "female")
                        ) {

                    simTraversal = simTraversal.has(USER_LABEL, USER_GENDER_PROPERTY, gender.toLowerCase());
                }

                GraphTraversal<Vertex, Object> targetTraversal =
                        simTraversal.properties(USER_ID_PROPERTY).value();

                while (targetTraversal.hasNext() && recoList.size() < limit) {
                    Object candidateUserId = targetTraversal.next();
                    if (!knownPersonIds.contains(candidateUserId)) {
                        recoList.add(candidateUserId);
                    }
                }
            }

        }
        long endSimilarIteration = System.currentTimeMillis();
        log.info("Stats : Similar iteration tooks : {} with result size : {}",
                endSimilarIteration - startSimilarIteration, recoList.size());

        log.info("Result recommendation list size : {} for user id : {}", recoList.size(), userId);
        return recoList;