} catch (final IOException e) {
            throw new SuggesterException("Failed to SuggestItem from search words.", e);
        }
    }

    @Override
    public List<SuggestItem> parseQueryLog(final QueryLog queryLog, final String[] fields, final String[] tagFieldNames,
            final String roleFieldName, final ReadingConverter readingConverter, final Normalizer normalizer) {

            if (parallel) {
                stream.parallel();
            }
            final SuggestItem[] array = stream
                    .flatMap(queryLog -> contentsParser
                            .parseQueryLog(queryLog, supportedFields, tagFieldNames, roleFieldName, readingConverter, normalizer).stream())
                    .toArray(n -> new SuggestItem[n]);
            final long parseTime = System.currentTimeMillis();